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AGARDograph No. 199 A Guide to Reprographic Processes for the Small User by T. Hampshire
DISTRIBUTION AND AVAILABILITY ON BACK COVER
AGARD-AG-199
NORTH ATLANTIC TREATY ORGANIZATION
ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT
(ORGANIZATION DU TRAITE DE L'ATLANTIQUE NORD)
AGARDograph No. 199
A GUIDE TO REPROGRAPHIC PROCESSES
FOR THE SMALL USER
by
T. Hampshire
The National Reprographic Centre for Documentation The Hatfield Polytechnic
This report was prepared at the request of the Technical Information Panel of AGARD THE MISSION OF AGARD
The mission of AGARD is to bring together the leading personalities of the NATO nations in the fields of science and technology relating to aerospace for the following purposes:
- Exchanging of scientific and technical information;
- Continuously stimulating advances in the aerospace sciences relevant to strengthening the common defence posture;
- Improving the co-operation among member nations in aerospace research and development;
- Providing scientific and technical advice and assistance to the North Atlantic Military Committee in the field of aerospace research and development;
- Rendering scientific and technical assistance, as requested, to other NATO bodies and to member nations in connection with research and development problems in the aerospace field;
- Providing assistance to member nations for the purpose of increasing their scientific and technical potential;
- Recommending effective ways for the member nations to use their research and development capabilities for the common benefit of the NATO community.
The highest authority within AGARD is the National Delegates Board consisting of officially appointed senior representatives from each member nation. The mission of AGARD is carried out through the Panels which are composed of experts appointed by the National Delegates, the Consultant and Exchange Program and the Aerospace Applications Studies Program. The results of AGARD work are reported to the member nations and the NATO Authorities through the AGARD series of publications of which this is one.
Participation in AGARD activities is by invitation only and is normally limited to citizens of the NATO nations.
Published January 1975 Copyright © Agard 1975
681.62:778.1:778.31
S> Set and Printed by Technical Editing and Reproduction Ltd Harford House, 7-9 Charlotte St. London, W1P 1HD SUMMARY
The report provides detailed information on the various reprographic processes and systems available. The information is divided into the three main areas of reprography:
Photocopying Duplicating and Printing Micrographics.
In general terms the method of operation of the processes is provided and the various characteristics and application suitability are given after each process explanation, a summary chart is included in the Photocopying section.
Mention is made of the required operator skills and comparative costings are provided for the Photocopying, Duplicating and Printing sections.
In general the equipment illustrations are intended to show type rather than specific- company's product. Therefore a list of major international manufacturers of equipment is included after each section to provide a guide from where specific information can be obtained.
RESUME
Le rapport contient de renseignements detailles des diverses procedes et systemes reprographiques disponibles. II se divise en trois parties suivant les trois domaines importants de la reprographie:
la Photocopie la Duplication et ITmprimerie la Micrographie.
La mode d'emploi de chaque procede est decrite en general et les particularites et l'aptitude a l'emploi sont donnees apres chaque explication de procede - un diagramme sommaire se trouve dans la partie "Photocopie".
On fait mention de la technique operationelle requise et les frais comparatifs sont donnes dans les parties "Photocopie" et "Duplication et Imprimerie".
En general les illustrations doivent demontrer le type d'equipement plutot que le produit d'un fabricant particulier. Ainsi une liste des fabricants internationaux les plus importants est apportee a la fin de chaque partie pour fournir une indication des sources de renseignements specifiques. CONTENTS
Page
SUMMARY iij
RESUME iji
1. EQUIPMENT AND SYSTEMS SELECTION 1
2. INTRODUCTION 1 2.1 Operator Skills 2
3. PHOTOCOPYING 2 3.1 Processes 2 3.2 Photocopier - Equipment and Materials Manufacturers 13
4. DUPLICATING 14 4.1 Spirit Duplicating 14 4.2 Stencil Duplicating 15
5. OFFSET-LITHO DUPLICATING AND PRINTING 17 5.1 Copy Preparation 5.2 Illustrations 19 5.3 Offset Masters 20 5.4 Collating 22 5.5 Binding 22 5.6 Papers 22 5.7 Duplicating and Printing Machine Materials - Manufacturers 23
6. MICROGRAPHICS 23 6.1 Flow Cameras 25 6.2 Planetary Cameras 26 6.3 Microfilm Duplication 26 6.4 Quality Control 27
6.5 Micrographics Equipment and Materials Manufacturers 29
7. COSTING 29
MANUFACTURERS AND DISTRIBUTORS ADDRESSES 32 A GUIDE TO REPROGRAPHIC PROCESSES FOR THE SMALL USER
T.Hampshire
1. EQUIPMENT AND SYSTEMS SELECTION
There are several basic rules or principles in purchasing for and equipping a reprographic centre.
Unfortunately only too often the major difficulty is to decide exactly what the centre will be required to produce. Many times too much emphasis is placed on "quality of copy" and always a practical decision must be taken.
Equipment must be selected that can be maintained by the manufacturer or agent, he must be able to supply at very short notice adequate supplies of materials to cope with the "job required now, not tomorrow".
The ideal situation arises when the reprographic requirement for example of production and quality level is known — then equipment can be selected to do that job; at this stage the possible bonuses of other work which can be done on the selected "machines" must be assessed, because these "bonuses" can sometimes save extra purchases or even extra staff.
The "services" to the equipment must be checked, e.g. water supply for film processes and power supply for machines above normal 13 ampere loading. Many reprographic machines consume large volumes of paper which has to be stored and transported within the centre both before and after machining.
Practically all the major manufacturers and suppliers of reprographic machinery have customer relations departments, these services should be used to the full. "When in doubt ask"!! is a good maxim.
Always beware the man who has something cheaper than the normal rate - check his product very thoroughly. Wherever possible buy or rent equipment that uses a range of consumables so that these supplies can be purchased at the best rates from a range of suppliers.
It is always good policy to get to know of other reprographic centres, much product information can be exchanged and quite often the essential of practical experience outside the suppliers showroom can save time and money, plus sometimes the embarrassment of buying the wrong product.
2. INTRODUCTION
The processes, uses and applications of reprography can be divided into three main groups: —
Photocopying Duplicating and Printing Micrographics and it is under these three headings that this report is compiled, despite the fact that some overlapping of process does exist e.g. xerography being applied to both photocopying and duplicating and the use of some photocopying processes for the production of duplicating masters.
The ever increasing use of reprography in all aspects of government and commercial life arises due to the needs of better communications. There is a constant need for economy and accuracy, the days of a typist preparing 1 + 6 copies on her typewriter are an action of the past, the office that received copy numbers 4, 5 and 6 was liable to make mistakes i.e. accuracy was lost due to poor legibility. At the same time as we look for accuracy it is essential that we look for, and retain economy, and in many instances where reprography is part of the communication system the economy factor starts with the answer to the question — "Can I read it"? Many reprographic processes and applications concern transient documents especially in the area of photocopying and here a second question arises "Do I need to go to the station in a Rolls Royce"?. At times the extra cost of extra quality is not justified and where wrongly used can have a great effect on the economic use of reprographic services. The installation of centralized reprographic services for organizations can lead to some financially accountable savings, for example the better use of equipment is usually possible, it is often possible to produce a cheaper end product by combining two processes on a production job and at the end the "cost per copy" which on many occasions is the yardstick can be reduced. But when considering centralized services take into account the hidden costs, staff time going to the central service, the messenger or internal postal service, the possible waiting time of staff, all these hidden costs affect the cost per copy and are often referred to as the convenience factor in arriving at costs.
When selecting reprographic equipment and processes, equipment should be chosen to meet the known need, having done this another look should be taken at the selection to see what bonus applications are possible. For example in choosing a photocopier the fact that a particular one will make visual aids in the form of overhead projector transparencies or perhaps duplicator stencil come in the area of bonus factors.
2.1 Operator Skills The degree of skill required for operating reprographic equipment varies from nil in the case of some photo copiers e.g. those sold by Rank Xerox, to a reasonably high level when offset litho machines are used for colour printing. It is fair to state that for operating some photocopiers, duplicating machines and microfilm cameras training is usually required, the main characteristic of an operator should be common sense. To train a photocopier operator takes no more than a half day, a spirit or stencil duplicating operator a maximum of two days, an offset litho duplicator operator a week to ten days depending on the complexity of the machine. To train the latter for reasonable quality printing work an extra two or three days will usually suffice because the essential requirement in this area is practice and more practice.
3. PHOTOCOPYING
Due to a variety of reasons photocopying has had a rapid rate of expansion over the past 25 years. Today the greater part of the market is taken up by companies selling or leasing machines designed around processes which are exceedingly simple to operate and therefore can be put in "help yourself locations within organizations. While this system does cause other problems such as "illicit copying" the main part from the photocopying angle in these notes is simplicity. This has meant in some cases the disappearance of some processes completely and a tremendous reduction in others, in fact in some cases the original manufacturers now only supply materials and no longer make and sell the hardware.
Nevertheless all the time processes are in use it often means that they are in special applications. For this reason details of them are included in these notes.
3.1 Processes The selection of the photocopying process to be used will, to some extent, be dictated by the size of the original, whether it is printed on both sides of the paper, is coloured, or printed on coloured paper, or includes illustrations as well as text. The quality and permanence of the reproduction will also depend on the process employed. Some processes will produce copies on card and tinted base papers for systems applications, on gummed paper or transparent plastic sheets, or produce masters for multicopy processes.
Another important factor is the time take to produce copies either singly or in multiples. In the latter case it is often necessary to utilize more than one process to ensure that the application is economical.
There are four main types of processes in use today, and in some of them there are variations.
1. Silver halide 2. Diazo 3. Thermographic 4. Electrophotographic.
A brief description of each follows, and at the end a summary chart of the process details is given.
3.1.1 Silver Halide Processes Conventional photographic papers are coated with an "emulsion", which consists of a mass of microscopically small, light-sensitive silver halide crystals embedded in a layer of gelatine. The more sensitive "projection speed" papers can only be handled in a photographic darkroom, but less sensitive papers commonly used for document copying can be handled, with caution, in normal office lighting.
After exposure to the intense light of the photocopier, a few atoms of metallic silver are produced on the surface of the crystals, and form an invisible "latent" image. These act as a catalyst when the paper is immersed in a developing solution, and the exposed crystals are converted into black filaments of silver which constitute the photographic image. The remaining crystals in the unexposed areas are then converted into a soluble salt in a fixing solution, and subsequently washed out of the paper. The print is then dried on a heated drum.
Copies produced by this method, which have been properly fixed and washed have archival permanence, and an excellent quality not yet matched by any of the more recently introduced processes. An example of this process is the Photostat* system.
3.1.2 Projection Copying (Photostat) A large semi-automatic camera is used to produce same-size, enlarged or reduced copies on silver halide papers. "First copies" are negative in sensation (white lettering on black background), but right reading. "Second copies", made by re-photographing the negatives in the same camera, are positive in sensation, i.e. like the originals. Excellent quality reproductions can be obtained up to a maximum size of 18 inches x 24 inches, from all types of original.
An expensive and slow process requiring a skilled operator.
These cameras are not now in production.
A4 size copies from approximately 5p.
3.1.3 Reflection Copying (Reflex) Reflex printing is a contact copying process yielding same size copies from double-sided and opaque originals on a variety of sensitized papers. The sensitive side of the paper is placed in contact with the document to be copied, and exposed through the back as shown in Figure 1. The image is formed by the light reflected from the background of the document, but insufficient light is reflected by the lettering to overcome the sensitivity threshold of the emulsion. The exposed sheet is then processed by conventional photographic processing as previously described or by the silver stabilization technique to create a white on black, mirror image negative. This paper negative can be stored thereafter exactly as a film negative from a camera and used to produce positive prints whenever required.
Original face down Sensitised I T I T paper face down Sensitised paper face up Negative face up A A * A
Stabilisation: Reflex: negative and positive exposed and developed QMQ> Fig. 1 Reflex exposure method To produce a positive print, the negative copy is placed in face contact with another sheet of the same copy paper. The exposure is made, this time through the back of the negative on to the coated side of the copy paper at approximately twice the exposure time selected to produce the negative. The copy paper is then processed and the positive copy produced is printed black on white. As many copies as are required can now be produced merely by repeating the exposure with the negative and passing the copy papers through the processor. The reflex process can be used to make white on black readable negatives provided the original is printed on one side only and is exposed by placing the printed face away from the negative copy paper. 3.1.4 Silver Stabilization Process This process is a departure from conventional silver-halide processing and permits the rapid processing of the exposed materials. The fundamental difference between conventional processing and processing by the stabilization method lies in the different chemical treatment of the exposed and developed silver-halide image. The light sensitive emulsion is different only in the fact that it contains the required developing agents and therefore after exposure it is only necessary to activate these with a solution and development can take place rapidly and evenly by machine. In place of conventional fixing, stabilization is used and the unexposed silver salts * Photostat is a trade name of the Kodak Co. are rendered inert by chemical action instead of being dissolved out by the fixing bath. This is the complete processing and takes about 15 seconds to complete — prints are damp dry when they come from the processor. In addition to the range of silver stabilization materials for reprographic applications a range is available for photographic applications where continuous tone prints are required. Due to the very short developing time it is virtually impossible to manual process silver stabilization materials. Processing machines vary slightly in the method of applying and the amount of solution used at both the activation and stabilization stages. Care should be taken to ensure that the machine purchased gives complete processing especially where continuous tone materials are involved. A wide variety of coatings are available and many different bases are used. It should be noted that materials designed for this process can also be processed by conventional photographic means. Cost of equipment £50-£150. A4 paper costs about 3.48p per sheet. Process details: Wet Printing Contact-Reflex-Projection Permanence Limited Detail Very good Contrast Very good (Variable) Colour Good Paper Coated Curl Average Waste Average Speed A4 20 sees up 3.1.5 Autopositive In 1840, Sir John Herschel observed that red light had a bleaching action on previously exposed, but undeveloped silver halide paper. Autopositive papers now marketed, are pre-fogged by the manufacturer, and exhibit the Herschel effect to such a pronounced degree that reflex exposure by yellow light from a single-sided document, is sufficient to destroy the latent image, and produce a direct positive copy by normal development and by silver-stabilization processing. High contrast papers are used which gives poor half-tones. The thin paper tends to curl, and is mainly used for making translucents for diazo printing, from opaque originals. Cost of equipment £100 £200. A4 paper costs about 2d per sheet. 3.1.6 Diffusion (Chemical) Transfer This process utilizes a special silver-halide emulsion and a receiving sheet. When the emulsion is exposed by the contact-reflex method to an original and developed, the silver salts in the background area which have been exposed are converted to black metallic silver — the image area which has not been exposed still contains unexposed silver salts which in the ordinary photographic process would be dissolved out by the action of the fixer. In diffusion transfer processing the exposed negative plus a receiving sheet are processed simultaneously in a simple machine (Fig.2) which keeps the sheets apart long enough to allow them to become moistened by the developer. In the course of 20-30 seconds, which is the processing time a complex chemical action takes place. The presence of a solvent (developer) for silver halides causes the undeveloper silver salts in the image areas to transfer by diffusion into the receiving sheet in the course of which they become reduced to black metallic silver to form a positive image. The two sheets are then separated by peeling apart. Except for the production of overhead projector transparencies the use of this process as a purely photocopying method is declining but an ever increasing use of it is being made in offset litho for copy proofing and offset litho plate production by contact and projection methods. Cost of equipment £20-£100 for photocopying use and £100+ for offset plate making use. A4 paper print costs 5.06p. Positive face up Negative face down Developing fluid Fig.2 Diffusion transfer process Process details: Wet Printing Contact - Reflex Permanence Limited Copy of C/Tone Poor Detail Very good Contrast High Colour Good Paper Coated Curl Average Waste High Speed A4 60 sees up 3.1. 7 Gelatin — Dye — Transfer Process This process is essentially a process whereby a soft gelatin image containing developed silver halides and dye is used as a printing matrix from which prints can be obtained by physical transfer of the soft gelatin. A copy is made by exposing the light-sensitive matrix by the contact-reflex method to an original. The exposed matrix is then activated in a tanning developer (tanning developer hardens the exposed areas). The soft dyed gelatin of the image area is then transferred to the receiving sheet by squeegee pressure - thus activating and transferring method can be repeated up to 6 or 7 times for multiple copying work. The process can also be used for making offset litho plates. Equipment not now in production and the process is little used today. Process details: Wet Printing Contact — Reflex Permanence Limited Copy of C/Tone Poor Detail Fair Contrast High Colour Very good Paper Plain Curl Average Waste Average Speed A4 90 sees up 3.1.8 Diazo (Dyeline) Diazo is a positive working process of dye bleaching by ultra-violet radiation, necessitating a mercury vapour light source, or a special type of fluorescent tube. Papers are coated with a yellow diazo compound which combines with a "coupler" in an alkaline environment to form a coloured dye. The diazonium salt is decomposed by ultra violet exposure, and will then no longer "develop" to a dye image. Three types of coating are available for use with dry, semi-dry and heat developing units. In the first type the coating contains both diazo compound and coupler, which combine in the ammonia vapour liberated in a developing chamber. The second type contains only the diazo compounds, the liquid coupler being applied by moistened rollers in the developing machine. The third type contains the diazo compound, coupler and an alkali generated chemical. On heating to the required temperature in the developing unit, ammonia is generated and the azoic dye is formed. In operation the process requires that the original to be copied must transmit ultra-violet light - the original is placed on top (face up) of the diazo coated sheet and exposed to the light source (Fig.3). Where the coating is protected by the image on the original the diazonium salts remain active, where they are unprotected the light decomposes them. On processing, the active salts form a visible image. Original Fig.3 Diazo process The main use of diazo is reproduction from technical drawings at low cost, however this process can be used as an "aid to draughting" and much drawing time can be saved by the use of diazo coated speciality products. (A film describing some of these applications is available on free loan from ICI Film Library, Millbank, London, S.W.I, and is entitled "Template for Draughting".) As an office document copying process there are problems, the main one being this requirement of the original passing ultra-violet light - however where an organization can control its internal documents and have them printed on tracing paper, Diazobond or plastic, then diazo can be a very cheap method of reproduction both in ordinary copy sense and as a system application e.g. stores ordering etc. Equipment costs from £200-£9000. A4 diazo prints on medium weight paper 0.6p per sheet. Process details Wet or Dry Printing Contact - transmission Permanence — Limited Copy from C/Tone — Fair (depends on material used) Detail Good Contrast — High Colour — Limited Paper — Coated Curl Average Waste Low Speed Varies 3.1.9 Thermographic Thermographic papers are not sensitive to light, but blacken immediately when heated to a temperature of about 100- 120°C. The copy paper is placed, sensitized side up, on top of the document to be copied, and fed past an infra-red lamp. The black ink will absorb the heat rays, and the temperature differential between the print and paper is sufficient to "scorch" an image on the copy paper. Unfortunately very few coloured and some black inks absorb sufficient heat to record on the copy paper. This process is now mainly used for the production of overhead projection transparencies rather than for conventional photocopying. (a) Thermofax Thermo-copying materials consist of a thin sheet of paper coated with chemicals which react, when heated, to develop a coloured image. It gives a fast four-second copy, and is a completely dry process. The quality of the copy is not very good, and the image is unstable. A range of tinted papers is available for systems work, and gummed and perforated sheets for addresses. Transparency materials are available in a wide range of base colours. Cost of equipment £100-£150. Standard paper A4 size costs about 2p a sheet. Process details: Dry Printing Contact - Reflex Permanence Limited Copy from C/Tone Poor Detail Poor Contrast Moderate Colour Limited Paper Coated Curl Average Waste - Average Speed A4 5 sees (b) Dual spectrum This process overcomes the colour-blindness of the other infra-red processes, and derives its name from the fact that it is exposed to light and developed by heat. An intermediate sheet coated with a dye sensitized alpha naphthal is exposed with the original to reflected light. The intermediate - now carrying a latent image - is placed in contact with a sheet coated with a layer containing silver behenate. The latent image is heated and the two compounds react to form an image on the copy paper. The result is a good quality copy which is now insensitive to heat, produced by a completely dry process. Machines are available for low output requirements as desk top models, while an automated model is now available for medium volume users, and in some applications these compare very favourably with the cost of electrographic copying. Cost of equipment £100-£500. Materials cost 1.72p to 3.36p an A4 size copy. Process details: Dry Printing Contact - Reflex Permanence - Limited Copy from C/Tone — Fair Detail Good to very good Contrast — Moderate Colour — Good Paper — Coated Curl Average Waste Average Speed A4 - 30 sees 8 3.1.10 The Eichner Process — Germany This process is a variant on the thermographic process and was developed by the Eichner Co. of West Germany. A sheet coated with a heat sensitive dye (known as a thermocarbon) is used as an intermediate for the formation of an image by the action of heat. To copy a document, a receiving sheet of plain paper is placed between a thermo carbon sheet and the original. Infra-red radiation is passed through the thermocarbon and the receiving sheet to the face of the original where it is absorbed by the image and dissipated in the form of heat at a high enough temperature to cause the coating on the thermocarbon to soften and adhere to the receiving sheet. As is the case with the other thermographic process, the Eichner process can only copy from original where the image thereon has a metallic or carbon content. Process details: Dry Printing Contact - Reflex Permanence Not known Copy from C/Tone Poor Detail Poor Contrast High Colour Limited Paper Plain Curl Low Waste Moderate Speed A4 15 sees 3.1.11 Electrophotographic Basically, there are two methods used to produce electrostatic prints. These are called direct and indirect. The direct method can be further subdivided according to the method of development into powder and liquid development. There are two basic principles involved in the production of prints. The first is that some substances have the characteristic of being insulators in the dark and conductors in light. Such substances are called photo conductors. The second is that particles which are charged will migrate to areas of lower or opposite charge. Considering the indirect process (Fig.4), the photo-conductor used is selenium, although the complete range of useable photo conductors can be zinc-oxide, selenium, sulphur selenide, cadmium sulphide and various others. The surface of the photo conductor is first charged by a corona, which typically has a static voltage of around 14,000 volts. Exposure is now made and in the photocopying processes we are considering, this will be a positive original. Thus the background areas which reflect more light than the lines, will reflect enough light onto the charged areas of the photo conductor to discharge it, because in those areas it has become conductive, thus allowing the charge to leak away. So at the end of the exposure, the photo conductor contains a latent image in the form of charged areas where there were lines on the original and discharged areas where there were light areas on the original. Development consists of cascading the whole of the photo conductor with particles carrying an opposite charge to that given to the selenium. Because opposite charges attract, the particles will stick to the still charged parts of the selenium, but not to the discharged areas. If, now, a piece of paper is laid over the photo conductor and a strong charge of opposite polarity to the powder is given to the paper, the particles will leave the selenium and stick to the paper. We now have an image on paper, which is, in fact, the print. At this stage, the powder is adhering to the paper because of the attraction due to opposite charges, so if it is rubbed or touched, it will come away. The fixing stage is to heat the paper with its powder. Because one of the constituents of the powder is a resin, heat will cause this to "melt" and become part of the paper surface. This method is called indirect because the final print is obtained indirectly from the charged photo conductor. If the final print paper was coated with the photo conductor, this would become the print directly; hence the name direct for this method. Cost of A4 copy on meter 1.09p to 2.07p. *•*•• + •• +++ + + + ++ + -H •+++++++4 + *--* + *- + + + + + + + + *-M +••• + + + + + •• + + + + + 4 4-4- + + + + + + + + + + + 4 + *- + + * + + + + + + + + + + + I *+++++++++++++•• *»•+•++++++4+++* ' t--f+ + + + • + + + + + + + + ••4 + 4- + + V + + + + + + + + 1-4 + + + + +- + + + + + + + + * + *••+- + •••••-• + ••••••• *-* + *4--*.+- + + 4- + +++ + H--H- • +• + +• * + + •• I -»•*•• + •»•••* «"•* «• •»•*••••• + *•+•»••• •** + + * + * + + +•* + + ••••• + + •••••• How Xerography works: 1 & 2 The selenium drum is positively charged by wires 3 The image projected onto drum (charge leaks off non-image areas) 4 Negatively charged toner powder adheres to image 5 Copy paper fed over drum and positively charged 6 Positively charged paper attracts powder 7 Print is heat fused Courtesy: Rank-Xerox Ltd Fig.4 Xerographic process Process details: Dry Printing Projection Permanence Archival Copy from C/Tone Poor Detail Very good Contrast Very good Colour Good Paper Plain Curl Low Waste Low Speed A4 1 sec upwards 10 The usual coating given to the paper for direct electrophotographic copying (Fig.5), is zinc oxide. Various additives are mixed with it to increase its spectral sensitivity or increase its speed, and so on. As before, the surface is charged and exposed, leaving a latent image consisting of areas of different charges, or areas having a charge with other areas having no charge, according to the quantity of light reaching the various areas concerned. Again, particles AUTOMATIC PAPER FEEDING DEVICE 250 SHEETS CORONA UNIT -SENSITIZES ^THE COPY PAPER EXPOSING AREA-COPY PAPER IS EXPOSED TO LIGHT TO FORM A CHARGED LATENT IMAGE COPY OUT CONTAINS CHARGED ORIGINAL OUT PARTICLES ORIGINAL IN CHARGING 2. EXPOSURE 3. IMAGE DEVELOPMENT 4. FUSING Fig.5 Electrofax process of opposite polarity are introduced to the differentially charged surface and are attracted to oppositely charged areas. If the particles are in the form of a powder, they will contain a resin and heating the surface will produce a perman ent print. If the particles are suspended in a liquid, the same attraction will occur, but heating is not necessary because the particles will permanently adhere to the paper in the same way as India ink, which is solid particles in water, will adhere to paper when the water has evaporated. Cost of equipment from £200-£3500 or can be rented. Average cost per A4 copy l.Op to 2.5p depending on volume 11 Process details: Dry Printing Projection Permanence Archival Copy from C/Tone Fair Detail Very good Contrast Very good Colour Good Paper Coated Curl Average Waste Low Speed A4 Approx. 10 sees Quite recently a new range of plain paper copiers has come onto the world markets, these usually combine the process details of both the indirect and direct systems. In place of the usual selenium drum these new machines use a band or web coated with zinc oxide or similar chemical photo-conductors onto which the powdered image is created - thus this now works in a similar manner to the selenium system whereby the image is transferred onto plain paper and fused. Other processes of interest but not necessarily used in photocopying applications. 3.1.12 Dry Silver Process This process is negative working and uses a coating which can be either on a paper or film base. It contains light sensitive substances which are developed by heat to form a visible image after exposure thus the process is completely dry. Its main area of application at the moment is for print-out from micro-images and the emulsion speed is high enough for this type of projection printing. Laboratory coatings have already shown that this process will be suitable for printing from continuous tone negatives onto a paper similar in appearance to what is now conventional glossy bromide paper. An important application in this field will be the high-speed print-out from aerial photographs. Process details: Dry Printing Projection Permanence Not known Copy from C/Tone Fair Detail Very good Contrast High Colour Good Paper Coated Curl Average Waste Low Speed A4 10 sees 3.1.13 Polaroid Process This is a sophisticated development of the diffusion or chemical transfer process. In this case the emulsion which is camera speed is coated onto a film base and a pack is made consisting of the negative film and positive paper and a pod of a chemical reagent which produces the negative and positive images. The design of the camera back is such that after the exposure is made a tab is pulled which advances the sensitized material out of the exposure area and through pressure rollers. These burst the pod and spread an even layer of chemical over the surfaces of both negative and positive materials. After a few seconds these are peeled apart as in conventional diffusion transfer, the positive print produced is to a high photographic standard. 12 Materials are available for: Lantern slides Half-tone prints Colour prints Standard continuous tone. Process details: Dry Printing Optical copying Permanence Archival Copy from C/Tone Very good Detail Very good Contrast Good to very good Colour Good Paper Coated Curl Average Waste Average Speed A4 2 mins up 3.1.14 Electrolytic Process The electrolytic process is a negative working process which yields positive prints from film negatives. These negatives can be microfilm and it is for use in this area that the process was developed. The 3M Co. use the process in some of their range of microfilm reader/printers. The sensitized material consists of three layers: (a) A paper base. (b) A thin metallic substance that acts as a conductor. (c) A zinc-oxide coating in a resin binder. The zinc-oxide coating provides a photo-conductive layer which in the dark acts as an insulator, i.e. has a high electrical resistance. The action of light during exposure lowers the resistance in the areas where light strikes the surface. Thus a latent image is formed in terms of differences in electrical resistance, the image areas having become electrically conductive through the action of light. If the exposed sheet is then placed very briefly in contact with a suitable electroplating solution and if a direct current electric potential is applied, current can flow between the solution and the conductive layer. The result is an electro-plating action whereby metal ions "plate out" or deposit on the zinc-oxide surface in the image areas to form a visible metallic image. This processing step in which electrolytic formation of the image occurs is accomplished with great simplicity and rapidity, requiring nothing more than drawing the zinc-oxide surface over an ordinary cellulose sponge soaked with the solution. The processing of an A4 sheet takes about 5 sees and as the surface is only moistened during processing the print can be considered for all practical purposes as dry. Process details: Dry Printing Projection Permanence Archival Copy from C/Tone Fair Detail Good Contrast Low Colour Limited Paper Coated Curl High Waste Low Speed A4 10 sees 13 Dual-spectru m Electrophotographi c Electrophotographi c (Electrofax ) Dyelin e (Diazo ) Thermofa x (Xerography ) Diffusion-Transfe r Photo-stabilizatio n Auto-positiv e Gelatin e Transfe r Conventiona l Silver-Halid e Copies from Yes Yes Yes Yes Yes Yes Yes Yes Yes Opaque originals Copies from Yes Yes Yes Yes Yes Yes Yes Yes Yes coloured originals Copies from half Yes Yes Yes Yes tone illustrations Will produce Yes Spirit masters Will produce Yes Yes Yes Yes Yes Yes Dyeline masters Will produce Yes Yes Yes Offset masters Colours which do Yellow Blue All Yellow not reproduce Time to produce 30 40+ 20+ 60 90 20 20 90 first copy (sees) Time to produce 50 250 copies (mins) Summary Chart of the Reprographic Processes 3.2 Photocopier - Equipment and Materials Manufacturers Silver Stabilization Ilford Ltd Kodak Ltd Autex John Blishen Ozalid Ltd Diffusion (Chemical) Transfer - Agfa-Gevaert Ltd Kodak Ltd Thermal — 3M Ltd Offrex Ltd Nig-Banda Ltd Eichner AG Diazo - GAF Ltd Ozalid Ltd Addressograph-Multigraph Ltd Harper & Tunstall Ltd Kalle AG Electrophotographic (Indirect) Rank Xerox Ltd Gestetner Ltd Agfa-Gevaert Ltd IBM Corp 14 Electrophotographic (Indirect) Kalle AG (continued) S.C.M. Ltd Mitsibushi Ltd Addressograph-Multigraph Ltd Electrophotographic (Direct) Apeco Ltd Addressograph-Multigraph Ltd Dennison Ltd Remington Rand Corp. Roneo & Vickers Ltd S.C.M. Ltd van der Grinten Ltd Lumoprint AG Nashua Copycat Ltd Agfa-Gevaert Ltd Minolta A.B.Dick Corp. GAF Ltd Pitney-Bowes Ltd Savin Ltd Ricoh Arcor 4. DUPLICATING Up to a few years ago it was generally accepted that there were three systems or processes of duplicating: Spirit (Hectographic) Stencil Offset-Lithography but with the introduction of the Xerox Model 2400 copier/duplicator (later to become the Model 3600) an important additional system became available. The importance of the new system was its simplicity of operation and the claim that anybody could operate the equipment, despite its very complex internal working, is true. Nevertheless the "traditional" systems of duplicating remain, and have operational and cost advantages which are important and various comparisons can be made when selecting the process best suited to a particular application or condition. 4.1 Spirit Duplicating In this process the fact that a heavy deposit of carbon can gradually be softened by contact with a spirit solvent is the key to the process. A spirit master can be prepared in several ways, by hand drawings, keyed on a typewriter, or on a thermal photocopier. The essential point is that a heavy deposit of carbon forms a mirror image on the back of the master sheet. This master is attached to the duplicator cylinder by a straight edge clamp. Only the leading edge of the master is held, the bottom being left to trail, thus permitting the use of various size masters according to the work requirement. Depending on the colour of the carbon used in creating the master depends also the colour of the duplicated image. As it is possible to change carbons during the preparation of the master then it follows that the final duplicated image can be similarly coloured. This is an exclusive feature of spirit duplicating, with one master and one pass through the duplicator multi-coloured work can be produced. Operation is simple, with the master attached to the cylinder the machine is set in motion by hand or by power drive. Copy paper is fed under a felt pad (Fig.6), viscose sponge or moistening roller (Fig.7) which carries the solvent. The paper is thus dampened immediately before it comes in contact with the master. The solvent softens the carbon and a very thin layer of carbon is transferred to the copy paper, the solvent evaporating very quickly. Because the image on the master is in reverse (a mirror image) the resulting spitit duplicated copy is right reading. As the original layer of carbon is gradually removed at each pass through the machine the possible run-off figure is controlled by the thickness of the carbon deposit on the master combined with the level of solvent application. It is usual for simple spirit duplicators to have only two controls, one for the solvent flow to the applicator and one for the paper pressure roller. Both controls have an effect on quality and quantity of copies. Too much solvent will produce woolly copies, too little, weak copies. In the case of the pressure roller too much pressure will produce good definition but lower the number of copies produced and too little pressure the reverse effect. 15 spirit reservoir master spirit reservoir ^K.^^ "\ damping pad damping rolle paper transporting roller TT=-r pressure roller feed tray ^^/^- pressure roller master cylinder Fig.6 Spirit duplicator (pad type) Fig.7 Spirit duplicator (roller type) In the more complicated machines used for system application duplicating the same duplicating controls exist but additional system features are fitted. These include line selection, a feature enabling the operator to select individual lines of information from a single master and to print that one line. Some machines are fitted with copy paper feeders that will feed various sized sheets in various weights of paper and card stock. There is no doubt at all that as a straight duplicating system the use of spirit is continuing to decrease. The handling of carbons by typists and operating staff is disliked, hands become dirty and time is lost through frequent hand washing. However the process when used in the systems field of applications such as production and stock control, export invoicing and shipping documentation it is very efficient and economic. In these cases, the present trend is to prepare the spirit master using a thermal photocopier from original material typed on white paper. A great deal of knowledge of systems applications using spirit duplicating is held by the manufacturers and it is a process which should not be ignored when considering equipment and processes for this type of work. 4.2 Stencil Duplicating Of the duplicating processes it is probable that the most widely used is stencil duplicating. Practically every typist learns to use it during her training, hence its appeal to management especially in small units; in some instances no extra duplicating staff need be employed, duplicating can be part of a junior typists work. Stencils are made from a strong fibrous tissue coated on one side with a sealing compound that will prevent the passage of ink through the tissue. The term usually used in preparing a stencil is "to cut a stencil" - this is nearly true. What happens is that where an image is required to be printed the sealing compound has to be removed or pushed to one side, thus leaving the fibrous tissue through which ink can be squeezed. Stencils can be prepared in several ways, the most usual by direct typing without the typewriter ribbon coming between typewriter key and stencil, it is possible to draw on stencils, in this case the correct wheel pens and backing sheet available from the stencil and duplicator manufacturers must be used (these should also always be used for underlining and ruling tables, ruling should never be done using a typewriter as this method cuts the stencil to pieces). Where stencils are required from existing copy an electronic stencil cutter or thermal photocopier can be used. The process of duplicating from stencils is simply a matter of squeezing ink through the cut image. The stencil is clamped face down around the duplicator band or drum, the ink squeezed through onto the copy paper. For the ink to pass through the fibrous stencil it must be very soft and usually oil-based and not quick drying. Therefore the copy paper must be such that it will absorb the ink and assist drying at a rate fast enough to avoid ink set-off onto the back of the following sheet. There are two systems of inking in stencil duplicating, the capillary drum (Fig.8) and the twin cylinder (Fig.9). In the drum method, the drum is a perforated cylinder covered with an absorbent cloth or silk screen, the drum has solid sides. The ink is contained within this cylinder and spread automatically over the inside of the perforated surface by centrifugal action when the cylinder revolves. To assist the required even spread of the ink and to regulate the flow, there is a free running felt covered roller inside the cylinder, the control of this roller is by an on/off lever. The centrifugal action forces ink through the perforations to the absorbent screen and thence by capillary action to the master. Wastage is kept to a minimum since the unused ink drains back into the drum. Control of print quality can be obtained by regulating the machine speed. A feature of this system is the facility to change ink colour easily it is only a matter of changing drums and a colour change is made. The twin-cylinder system is claimed to offer better ink control - here ink is fed to oscillating rollers by which it is evenly distributed over the outside of the cylinders. A carrier screen, which holds the stencil, travels round the cylinders which are located above and below the ink injection system. This method allows the operator full control over inking, from regulating the replenishment rate during automatic inking to positioning the ink across the width of the cvlinders. 16 Twin cylinder ink injector cylinder waver-rollers Capillary drum distributing ink evenly over the cylinders inlptl nk rolltr stencil direction of pater 'low paper—• receiving impression through imortiiioa roller stencil impression roller oioor secondary Ited rollers Fig.8 Capillary drum stencil machine Fig.9 Twin cylinder stencil machine Of the two systems of inking the single drum method is simpler, the automatic inking being quite adequate for normal work and it is slightly more economical in its usage of ink. A wide range of machines from several manufacturers is available, they are in two sizes of foolscap (taking A4) and brief (taking A3), machines can be hand operated or power driven. 4.2.1 Electronic Stencil Cutters These machines have rotating cylinders (Fig. 10) on which the document to be copied and the special uncut electronic stencil are placed side by side. The original is scanned by a photo-electric cell which reflects light signals which are converted into electrical heat impulses via a stylus running on the stencil. When the photo-cell does not reflect light, i.e. when it reads the image on the original, the stylus radiates heat and removes some of the coating original to stencil be copied rf7 drum motor <\MC)s -exciter lamps produce spot of light scanning carriage drive band - amplifier — photoelectric Fig. 10 Electronic scanner for stencils on the stencils. These electronic stencil cutters are very simple to use but they must be cared for and it is important that the stylus is kept clean and changed on an average of having cut 15 stencils. 4.2.2 Thermal Stencils These stencils can be used on thermal type photocopiers where the image on the original to be copied contains carbon. The quality is only average and they are not really suitable for fine work. Nevertheless applications for them do exist especially if stencil production speed is important as production time in seconds. 17 5. OFFSET-LITHO DUPLICATING AND PRINTING In the industry of printing there are three main processes in current use i.e. letterpress, photo-gravure or intaglio, and lithography. It is the latter process that is used considerably in reprographic units throughout the world in the form of offset-lithography. The difference between duplicating and printing is simply that the range of work in printing includes the production of more complex work such as line and half-tone illustrations in black and white and colour to a fairly high quality and the machine operators being more skilled and experienced. Lithographic printing depends on the natural repulsion of oil and water, by utilizing a flexible plate with a moisture retaining surface on which is imposed a greasy, ink receptive image. This is printed on a rotary press on which the ink is transferred or "offset" first to an intermediate rubber "blanket", and then to the paper, in order to obtain right-reading prints. Some manufacturers offer models with combined ink and water systems (Fig. 11), a single series of rollers carrying both ink and water to the plate. The majority, however, feature two separate systems (Fig. 12), one for inking, and one for dampening with the fountain solution. As the master cylinder rotates, the ink is transferred by light pressure from the image areas of the master to the blanket cylinder, and thence to the paper as it is fed between the blanket and impression cylinders. -NQO Fig. 11 Offset-litho fount dampening Fig. 12 Offset-litho conventional dampening Machines vary in many points other than the inking and dampening systems. Table-top models (Fig. 13) are available for simple duplicating applications, other machines are free standing and in some instances more complex (Fig. 14), both friction and vacuum paper-feed systems are available and a range of accessories for perforating and numbering can be fitted. A particular point to note when buying machines for quality printing is that the model chosen has at least two ink to plate (forme) rollers to ensure adequate inking. Copies may be printed on a wide variety of papers, boards and plastics, in an equally wide range of inks. To produce good, sharp copies with clean backgrounds the balance of ink and water must be controlled carefully. Correct roller pressures must also be maintained, and the system of air, rollers, belts and grippers which transport the paper must be adjusted according to the size and type of paper stock being run. A trained operator is essential except for very routine work where there are no variables. Fully automated machines, which virtually eliminate operator skills, accept the master, automatically apply the conversion fluid, ink and fount solutions, feed the paper and print the number of copies dialled on the machine, eject the master and clean the blanket ready for the next job. The main advantages of the small offset-litho duplicator in a reprographic unit, are low cost printing on the premises - especially on short runs, and scissors drafting which facilitates the combinations of text and illustrations, with ease and versatility. Paper masters are cheaper than stencils, and the copies may be on cheaper but better quality paper than that used for stencil duplicating. 5.1 Copy Preparation The electric typewriter is the usual composing machine for the inplant department, and when used with a plastic or one time carbon ribbon on a smooth white paper gives a crisp, uniform character impression. A popular machine also produces proportional spacing, i.e. letters spaced according to their unit widths to improve readability, and by double typing sub-headings can be emboldened, or lines of type may be justified to produce an even edge to the 18 right-hand side of the typescript giving the more finished appearance of a printed book. To assist the typist a lay-out sheet may be used with the permissible typing area indicated by a pale blue border line which disappears later in the process. Single Lever Distributing Roller Ink Vibrator Roller I Large Oscillator ^2 Stack Platform Scraper Bar Tension Adiustor Fig. 13 Table-top offset-litho machine Fig. 14 Free standing offset-litho machine 19 It is the duty of the author to see that the manuscript or copy passed for typing or printing is everywhere clean, tidy and easy to read. Double-line spacing of drafts is strongly recommended, and manuscripts in pencil should be regarded as unacceptable. More expensive typewriters have interchangeable type faces of various styles and sizes, including mathematical symbols and foreign alphabets. Some will operate automatically from punched paper tape or magnetic tape, at high speeds, and can be programmed to justify, hyphenate and tabulate to a prescribed plan. Lists such as bibliographies, telephone directories and catalogues can be prepared by typing on to cards - one item per card - and assembled on panels from which they can be reproduced. This system enables amendments to be made periodically by inserting additional cards, or obsolete ones. Small photo-typesetting machines are available which resemble, in function, a typewriter insofar as they produce letters and words selected by the operator from fonts of type faces, suitable for headlines and titles, and photographic ally acceptable for reproduction. Most models produce copy on stabilized photographic paper or film, but one modestly-priced machine utilizes the cheaper diazo paper to produce high contrast prints in daylight, without photographic solutions. Other machines are much faster in operation, and often enlarge, reduce, italicise, backslant, condense or expand from a wide range of type faces, and may even screen, bounce, stagger, arc and curve letters for creative composition. Even without the aid of these machines, very attractive lay-outs can be prepared by using the extremely compre hensive range of pressure-sensitive transfer letters and tapes now on the market. The range now includes shading tints and textures and art sheets - an illustrative studio in an album! Type sizes are often expressed in pica point sizes (or less frequently in didot point sizes), and it should be understood that the "point" measurement is of the metal on which the letter is cast, and not of the letter itself. So it is the length of the ascenders and descenders relative to the "x" height which regulates the point size of the letter. Some idea of the letter size will be gained by remembering that 1 pica point = 0.0138-inch, and 1 didot point = 0.0148-inch. 5.2 Illustrations Line diagrams and graphs may be included without difficulty, but if a fine mesh grid printed in a pale colour has been used, this may become too obstrusive and obscure the plotted curves when produced in black and white. For this purpose a special half-line graph paper should be used in which the grid consists of small chain dots. Photographs and art-work having a tonal graduation must first be "screened" (Fig. 15) to convert the tones into tiny dots varying in size according to the light and dark shades of the picture. The Polaroid Land M.P.3 camera will • • • • ••••• • ••••• • ••••• • •• ••••• • ••••••• • ••••••• • •••••••• • ••••••• • •••••••• • ••••••• • •••••••• Fig. 15 Half-tone screen and image produce suitably screened prints up to 5 inches x 4 inches in about one minute, without requiring a dark room, from a variety of originals. Alternatively, an "Autoscreen" photographic film is available from Kodak for use in professional cameras, which has incorporated in the emulsion during manufacture, an image of a half-tone dot pattern, and produces a half-tone negative by normal processing. Some degree of skill is necessary to obtain optimum results from these photographic operations. For large scale users a vertical or horizontal copying camera (Fig. 16) will be required, and half-tone negatives are usually obtained by photographing onto "litho" type film using a grey or magenta contact screen. These contact screens have a vignetted screen pattern and when used in conjunction with high contrast film the dot size will be proportional to the amount of light penetrating the graduated screen pattern, and therefore to the relative brightness 20 \ 2 MOVABLE BACK, LENSBOARD AND COPYBOARD MOVABLE LENSBOARD AND COPYBOARD Fig. 16 Process camera of the various tones of the original. It may also be necessary to give "flash" exposure to a white sheet of paper to obtain a small dot in the shadow areas. The more traditional method is by using an optical screen on a process camera but this would not normally be found in many in-plant departments. For clean and efficient paste-up of the copy, wax-coating machines can be purchased which will typically handle material up to 12 inches wide by any length, and be effective down to about |-inch x^-inch. At this stage it would be advisable to submit a proof to the author, before proceeding with any production work. This could most conveniently be done by submitting a photocopy of the make-up. 5.3 Offset Masters Direct masters may be produced by transferring a water resistant, slightly greasy image from special pencils, typewriter ribbons, etc. to a paper master, but for greater flexibility, lay-outs prepared by the methods described above may be converted to offset masters by the following methods. The cheapest method is by using an electrophotographic photocopier, and rendering the zinc-oxide coated surface of the copy hydrophilic by the application of conversion fluid. These masters will run at least 100 impressions, and cost about 2p each. Longer run masters are also available for use on this equipment. For longer runs the "Elfasol" aluminium plate originated by the "Kalle" company, may be used in conjunction with a special electrophotographic plate-maker camera. This plate has an organic semi-conductor coating, which is sensitized immediately prior to exposure by subjecting it to a corona discharge in the camera. After exposure it is passed through a developing chamber in which a charged black powder adheres to the image areas. Any necessary deletions can be made at this stage, then the image is heat fused, immersed in a decoating fluid, washed and gummed-up in the normal way. Another method of obtaining offset masters in specially constructed cameras (Fig. 17) is by using the Kodak "Verilith", 3M or Rotaprint materials. These are coated with two super-imposed photographic emulsions, the top one being pre-exposed and the lower one containing a restricted supply of a developing agent. After exposure in the camera, the plate is immersed in an activating solution which develops a negative image in the lower layer, exhausting the supply of developer in the exposed regions, but in the unexposed areas the unused developer diffuses into the upper layer to produce a positive image. A tanning agent is employed which hardens the gelatine adjacent to the image, thus inhibiting its ability to absorb water, and conversely its attraction for the printing ink. It is then fed through a stop bath, and is ready for the press. Masters can be produced at the rate of about two per minute, the length of run varies from manufacturer to manufacturer. The diffusion-transfer method of mastermaking, pioneered by the Gevaert laboratories, is now widely used. Neat machines for operating this process are now manufactured which consist of a light-box with a vacuum lid for perfect contact, electronic timer, and a register sheet to allow for the exact positioning of the original on the paper negative when exposing. After exposure the negative sheet is squeegeed into contact with a metal plate whilst immersed in a silver-halide solvent developing solution. On peeling apart, a negative image is found on the paper sheet, but the unused halides have diffused out of the emulsion and deposited electrochemically as a positive image on the plate. Plates for which runs of 40,000 are claimed, can be produced in under five minutes for 22V2p each. Diazo pre-sensitized paper, plastic or metal plates are commonly used for high quality work, including half-tones, and can be obtained for negative or positive working. These plates are exposed under photographic negatives or 21 Fig. 17 Direct plate making camera positives (paper or film), to ultra-violet light in printing down frames (Fig. 18) with vacuum lids. This exposure will decompose the diazo compound, which may cause a tanning action on a colloid binder, or cause the diazo photolysis product itself to become selectively solvent in the developer fluid. Development consists of wiping one or two solutions over the surface of the plate with cotton wool or a sponge and rinsing the excess off under a tap. The whole process, including exposure, takes about five minutes. Long runs and excellent quality reproduction can be expected from these plates. Fig. 18 Printing down frame 22 5.4 Collating Collecting together sets of pages in their correct order for binding is referred to as collating, and although this can often be done quite speedily by hand if the sheets are laid out on a bench, larger users may prefer to invest in an automatic or semi-automatic machine. The semi-automatic machines are relatively inexpensive, and merely advance the top sheet of each pile so that they can all be picked up together, or a rotating circular table with spirally located bins can also be used, the sheets being collected by hand as it revolves. More expensive, but also more efficient are the fully automatic machines which gather the sheets and jog them into sets at speeds around 12,000 per hour. Machines, usually large rotary drums, can sometimes be fitted to, and synchronized with the printing presses. 5.5 Binding One of the commonest types of binding is wire-stitching or stapling. This can be performed on small hand stapling machines, or power driven stitching machines which, in effect, manufacture their own staples from a reel of wire, and may be used for either side stitching or saddle stitching, i.e. stitching down the centre of folded pages. Various hot or cold adhesives can be applied to the spine of the book by hand or machine application, and a strip of self-adhesive tape down the spine will neaten the appearance, cover the staples and prevent the pages splaying apart. Another popular method is the plastic comb binding, and special machines are used to punch the rectangular holes down the edge of the sheets and insert the plastic binding. Yet another binding introduced more recently are PVC extrusions which grip the spine of the book, and can be securely fixed by a patented locking device. Guillotines, drilling and folding machines are other useful items of equipment, and covers can be improved in appearance and durability by laminating with a transparent plastic foil, on a suitable machine. 5.6 Papers Machine-made paper is made as a continuous flow through the machine. The pulp, which is a mass of vegetable fibres suspended in water, is pumped on to a moving wire belt through which surplus water escapes. To avoid some machining troubles caused by paper it is best to always have the grain of the paper in the same ] direction as the machine is rotating. For example A4 paper is fed with the short side (8 /4 inches) leading, in this case the grain should run the length of the sheet (11% inches) this is known as long grain. Conversely an A3 sheet is usually fed with the wide side (16% inches) leading, and in this case the grain runs on the short side (11% inches), this is grain short. In so doing, it leaves most of the vegetable fibres lying in one direction - the direction of the flow of the paper making machine - and this alignment of fibres is referred to as the "grain". It is often necessary to know the direction of the grain as under humid conditions the paper will stretch more across than along the grain, and the paper will tend to curl more when cut across the grain. This tendency to curl is, in fact, the usual method of detecting the grain direction. The publication in 1959 of BS3176 established standard international sizes for printing and writing papers. These are based on a sheet known as A0, which has an area of one square metre and sides in the ratio of 1:2, so that when a sheet is folded across the long side the proportions of sheet remain the same (a useful feature for reducing drawings, producing smaller reprints etc.). The description of the A series is simple: it consists of a capital A followed by a figure, e.g. A4. The basic size is described as A0, half A0 is Al, and half Al is A2. These notes have been printed on an A4 sheet (11% inches x 8% inches) and if folded in half would become A5. Landscape format is distinguished by the letter "b" following the number, thus: A4b. A2 The traditional method of quoting paper weight in lb per ream of 500 sheets in a given size is convenient only when a few sizes of paper are in use. The simplest method of stating the weight of paper required is by indicating the GSM (grammes per square metre of paper). The size of the sheet being ordered is then no longer a factor in the weight/size classification. For normal offset-litho work a cartridge paper in a weight of about 94 GSM is a good choice. "Art" papers, which are coated with china clay and/or casein, and have a glossy surface are sometimes recommended for half-tone printing. Whilst these papers give a crisper dot because the ink is not easily absorbed by the paper, this means that it is more difficult to dry and may cause the printed image to set-off on to the back of the next page. Anti set-off sprays can be fitted to the press which puff out a fine absorbent powder over the page - and everything and everyone else in the room! 23 5.7 Duplicating and Printing Machine Materials - Manufacturers Spirit - Nig-Banda Ltd Offrex Ltd Stencil — Roneo-Vickers Ltd Gestetner Ltd Offset-Litho - Addressograph-Multigraph Ltd Gestetner Ltd Rotaprint Ltd A.B.Dick Corp. Nig-Banda Ltd Roneo-Vickers Ltd ADM Business Machines Ltd Davidson Corp. Ricoh Itek Ltd 3M Ltd Kalle AG Ordina Pitney-Bowes Ltd Kodak Ltd Agfa-Gevaert Ltd 6. MICROGRAPHICS For some years now microfilming has ceased to be solely a means of photographing documents and the resulting reduced size negatives being filed away for safe keeping as an archival method of storage in a much reduced space. Modern microfilming now includes the use of the images in active business, technical and commercial use. The space saving of records, be they engineering drawings or file records still exists but speed of retrieval, referencing etc. are perhaps the major factors of microfilming systems today. For example engineering drawings can be reduced by 36x, the resulting negative being then mounted in an aperture card and the many advantages of data processing can be used to the full. Similarly reference material when filmed to reduction ratios of 24x onto 98 frame microfiche, can form the basis of a desk-top library. The filming and quality control processes have now reduced the photographic skills required for the production of high quality consistent micro-film to standard simple operations based around apparatus where the operator simply has to "press the button". The various "Standards" organizations notably ISO have produced practical, workable standards to ensure international consistency both of quality and format. The following paragraphs on "Micrographics" detail the essential of production of good microfilm. Standard microfilm as would be produced in a reprographic unit comprises images recorded at reduction ratios ranging from approximately lOx to 36x. These images are photographed onto either 16 mm and 35 mm roll film or as microfiche on 105 mm x 148 mm sheet film in a set format. These microfiche formats can be 60 frame (Fig. 19) or 98 frame (Fig.20) each having a title strip along the top edge. In this category of microfilming two basic types of camera are used - flow (or rotary (Fig.21) and planetary (Fig.22)); the latter can be further sub-divided into conventional planetary cameras and step and repeat cameras for the production of microfiche. The main difference between the two types is that in a planetary camera, the original and the film are stationary during exposure, while in a rotary camera both are moving. The choice of which type to install depends almost entirely on the type of work to be photographed. A flow camera is much faster in operation, but has certain limitations among which are, it will only accept single sheets; because the film and original are both moving it is not usually possible to obtain the same optical performance as is given by a planetary camera; and the reduction ratios cannot be altered during filming and mostly not at all. Its advantages are, it is very much faster in operation; it is possible to simultaneously expose two films as an original passes through and these may be either at the same reduction or different; it is possible for high filming speeds to be achieved; and the cost of a flow camera is usually less than that of a planetary camera. Additionally, there are two other considerations in the pros and cons of the two types; the first is that it is not generally possible to ensure even density of all frames on a flow camera, because there is usually no exposure assessing device, and secondly, the length of the frames produced on a flow camera depends on the lengths of the originals, a long original producing 24 a long frame, and vice versa. If it is the intention to subsequently produce microfiche by one of the stripping methods, then frame positioning cannot be accurate if a flow camera is used. TITLE AREA r*>* *1' »> c* I 2 3 4 5 6 7 B 9 10 M 12 Single frame TITLE AREA. i i ! **^\ y t\ J,C* o^r ^! i i i I 2 3 4 5 6 7 9 9 10 H '2 b Double frame Fig. 19 60 frame microfiche TITLE AREA .$ •> M.'l — -.^ A G* \KV 1 1 2 3 4 S 6 7 8 9 10 II 12 13 14 TITLE AREA » 1 Q . 1 c M . D ,> ! F 1 A**• ' 1 F ^ i I l G i 1 1 1 2 3 4 5 6 7 8 9 10 II 12 13 14 /• Ii ubk- fame Fig.20 98 frame microfiche 25 Fig.21 Flow camera Fig.22 Planetary camera If the resulting microfilm is to be used in an automatic retrieval device, it is necessary to have any necessary index marks exposed on the film at the same time as the information is exposed. Such index marks might be "blips" under each frame, or binary coding for each frame or a batch of frames, or "moving bars" which are photographed at the side of each original, and so on. When choosing a camera, the need of such retrieval markings should be considered and an appropriate model selected. Another feature of some flow cameras is the ability to annotate the originals as they are photographed. The annotation can be on the back of the original, when it acts as an indication that the original in question has been filmed. Conversely, the annotation can be sequential and appear on the front of the original, in which case the annotation is photographed and can form the basis of an indexing system. If scale accuracy is important, especially if prints are to be produced from the film, then thought to the accuracy of the reduction scales on the camera in conjunction with the actual enlargement ratio of a printer, should be discussed with the camera supplier. 6.1 Flow Cameras The way the original is fed into the camera will determine the way the negative appears on the film. The leading edge of the original will be across the width of the film, so if either "comic" or "cine" mode is required, this can be obtained by suitably feeding the original. In normal camera work, the images are required in comic mode, which calls for the width of the pages to be fed into the camera first. With a suitable flow camera it is possible to photograph simplex, duo or duplex. Simplex (Fig.23) is one line of images along the length of the film. 26 Fig.23 Simplex filming Duo (Fig.24) is two lines of images along the length of the film, obtained by filming along one edge, then turning it round and repeating the process along the other edge. This is the method used in the old "standard" 8 mm amateur cine filming, except that in the case of microfilm, the film is not split into two 8 mm widths as is the case with cine. 7J C Fig.24 Duo filming Duplex (Fig.25) in which both sides of a document are photographed as it passes through the camera, the images appearing usually side-by-side across the width of the film or more rarely, as two frames along the length. • Fig.25 Duplex filming 6.2 Planetary Cameras Planetary cameras are used when the highest quality film is required or when the originals are bound or too large to go through a flow camera. With a planetary camera it is not unusual to photograph more than one original on a frame, except in the case of engineering drawings when one frame for one drawing is the rule. An example of more than "one-up" is the microfilming of patent specifications. Eight pages are photographed on one frame of 35 mm film, so that one aperture card shows one complete specification, since it is not usual for a patent to consist of more than eight pages. One small point about operating a planetary camera, whether it uses 16 mm, 35 mm or microfiche film, is that the operator should ensure that her hands do not appear on the negatives. This can happen very easily if it is necessary to hold a page of a book open, to ensure that the original is flat. More than one organization has modified their cameras so that the shutter is operated by two hand buttons - one for each hand; unless both are operated, the shutter does not open. This ensures that it is impossible for the operator to have her hands in the area photographed. Most large planetary cameras have an illuminated baseboard. The theory is that when photographing engineering drawings, contrast is increased, resulting in better negatives. If the drawing is made in pencil, this theory is wrong, because contrast in the negative is decreased, not increased. The backlight shines through the background all right, but since pencil lines are not opaque, or anything like it, some light passes through these as well, making them less black than they would otherwise appear. If a highly reflective white sheet is under the drawing, the top lights cast a shadow of each line and the density of the shadow is added to that of the line and this does increase contrast. 6.3 Microfilm Duplication A duplicate is a facsimile of the microfilm and can be used in the same way as the microfilm. Duplicates can be made by one of three processes, viz: 1. Silver halide 2. Vesicular 3. Diazo. 27 The choice of process is governed primarily by the need for positive or negative duplicates. The main characteristics of the three processes are: Silver halide reverses the original, i.e. it gives a positive from a negative and vice versa. If bought in small quantities, it is the most expensive of the three processes; dark-room handling is necessary, although total darkness is not; processing requires solutions in a silver processor. Its advantages are that if bought in large quantities the cost is considerably less; it has greater exposure latitude than vesicular film, the other method of obtaining reversal; by varying the processing, it is possible to include tones and textual matter with good results; properly processed and stored, it has archival permanence. Vesicular film also reverses the original in the same way as silver halide. It is expensive compared with diazo, or with silver bought in large quantities; the exposure latitude is not great; if heated, the image will disappear, a condition that may be met if vesicular film is stored in fire-resistant cabinets during a fire, since although the cabinet has done its job and kept the contents below a certain temperature, the heat is still enough to destroy the vesicular image; it is liable to show abrasions during use through a motor driven reader; its advantages are that it can be worked in ordinary room lighting; it requires only the application of heat and light to develop and fix the image; one piece of uncomplicated machinery both exposes and processes the film; the image is visible within a few seconds of exposure, so consequently it is possible to correct exposure errors without wasting a lot of film. Diazo does not reverse the image, so a negative duplicate results from a negative master film or a positive duplicate from a positive master film. It is the cheapest of the duplicating processes; it is handled in daylight; no solutions are required for processing as modern machines work off bottled ammonia gas; it is not easily abraded during use; the image is visible within a few seconds after exposure. Its disadvantages are that although the manu facturers state that in normal storage conditions it has a life of 25 years, it is not considered as an archivally permanent material; on badly designed processors there is a smell of ammonia in the work room. Duplicating machinery is either roll to roll (Fig.26) or cut sheet to cut sheet (Fig.27), under the latter category is included the card to card duplicators (Fig.28) for 35 mm film in aperture cards. Fig.26 Roll to roll duplicator Roll to roll duplicators provide contact between the master and the copy film either by means of endless belts the usual method - or sometimes by the tension of the two films as they pass together over the exposing roller. Processing is usually part of the same machine in the case of diazo and vesicular, but with silver is separate. Cut sheet duplicators comprise two sections - expose and process. Sometimes these are parts of one piece of equipment and sometimes they are separate. The best types have vacuum contact for exposure, but these generally have a lower output than the "flow" types. 6.4 Quality Control For such work as, perhaps, flow camera recording of office correspondence where the film will never be duplicated or printed, and its only use will be on a reader, quality control will consist of no more than a check that all the images are legible. Even for such non-demanding work, however, some quality check is highly desirable, but for almost any other work it is essential. At the other end of the scale, when a 35 mm drawing office microfilm system is being operated, then quality control is just as vital as pressing the shutter release. The point being made 28 Fig.27 Cut sheet to cut sheet duplicator Fig.28 Card to card duplicator is that quality control is essential for good microfilm but the extent and the scope of the tests and supervision needs to be tailored to the particular application. One aspect of quality control not often highlighted is that a good original can provide an excellent negative. But a poor original that lacks contrast or is barely legible, can never produce an ideal negative, although the application of quality control can and will get the best possible result. Quality control is not just a series of tests on finished microfilm. It starts when the film is loaded into the camera and the originals are ready, and ends after the job has left the microfilming department. As well as the following tests for negative density, consistency, resolution, image position free from scratches and permanency, it is an act of supervision operative throughout the whole microfilming operation; the idea of the tests is to ensure that the supervision has been effective, not just to scrap film that is wrong. If this concept is followed, the amount of scrap will be very small indeed; if it is not, the tests are liable to fail quite a high percentage of the negatives produced. Quality control tests ensures that: 1. Negatives are all within the density tolerances. 2. Negatives are consistent, both all the negatives on a roll and all the negatives on all the other rolls. 3. The difference between line and background densities are controlled. 4. Images are of adequate resolution and are sharp. 29 5. Images are correctly positioned and are not reversed. 6. Negatives are in mechanically good condition. 7. The desired permanence will be attained. 6.5 Micrographics Equipment and Materials Manufacturers Kodak Ltd Bell & Howell Ltd 3M Ltd Caps Equipment Ltd Agfa-Gevaert Ltd Kalle AG Lumoprint AG Rank Xerox Ltd Scott Graphics Ltd Ozalid Ltd Bexford Ltd GAF Ltd 7. COSTING It is practically an impossibility to give accurate costings of the various reprographic processes. Circumstances, production levels, applications, over-heads and staff salaries are so variable. Add these to the ever rising material and labour costs and price discounts available from manufacturers for high volume production or quantity material purchases, and even the prestige value of some companies' business and it will be appreciated that only a series of comparative costs of the respective processes in a given set of circumstances are possible. These figures and the graph show the peaks and levelling-off points which will remain constant at these points but not necessarily at the same cost level. TYPICAL COMPARATIVE COST GRAPH FOR DUPLICATING PROCESSES Based on manufacturers' published figures to May 1974 NOTE: Actual costs change rapidly due to the continuous price increase of basic materials e.g., paper. Nevertheless the possible comparison between processes will remain. ,i„J r 300 20 40 60 80 100 NUMBER OF COPIES 31 Comparative Costs of Copying and Duplicating in a Semi-Governmental Establishment (in Sterling Pence) COPYING DUPLICATING Stencil No. of RANK-XEROX or Stencil Offset Gevafax Gevafax Bruning Offset from from copies 50 or Dennison X-10 or 2100 from electronic Bruning 3M191 AM610 422 720 4000 3600 typed master master masters 1 1.8 1.7 1.8 1.7 1.6 1.4 1.5 1.5 - - 2 3.5 3.4 3.5 3.3 3.1 2.8 3.0 2.9 10.4 17.4 12.4 3 5.3 5.1 5.3 5.0 4.7 4.2 4.5 4.4 10.6 17.6 12.6 4 7.0 6.8 7.0 6.6 6.2 5.6 6.0 5.8 10.8 17.8 12.8 5 8.8 8.6 8.8 8.3 7.8 7.0 7.5 7.3 11.0 18.0 13.0 10 13.8 13.3 14.2 11.3 15.5 14.0 15.0 14.5 12.0 19.0 14.0 15 18.8 18.1 19.6 14.4 23.3 21.0 22.5 21.8 13.0 20.0 15.0 20 23.8 22.8 25.0 17.4 31.0 28.0 30.0 29.0 14.0 21.0 16.0 25 28.8 27.6 30.4 20.5 38.8 35.0 37.5 36.3 15.0 22.0 17.0 30 33.8 32.3 35.8 23.5 46.5 42.0 45.0 43.5 16.0 23.0 18.0 35 38.8 37.1 41.2 26.5 54.3 49.0 52.5 50.8 17.0 24.0 19.0 40 43.8 41.8 46.6 29.5 62.0 56.0 60.0 58.0 18.0 25.0 20.0 45 48.8 46.6 52.0 32.5 69.8 63.0 67.5 65.3 19.0 26.0 21.0 50 53.8 51.3 56.4 35.5 77.5 70.0 75.0 72.5 20.0 27.0 22.0 55 58.8 56.1 61.8 38.5 85.3 77.0 82.5 79.8 21.0 28.0 23.0 60 63.8 60.8 67.2 41.5 93.0 84.0 90.0 87.0 22.0 29.0 24.0 65 68.8 65.6 72.6 44.5 100.8 91.0 97.5 94.3 23.0 30.0 25.0 70 73.8 70.3 78.0 47.5 108.5 98.0 105.0 101.5 24.0 31.0 26.0 75 78.8 75.1 83.4 50.5 116.3 105.0 112.5 108.8 25.0 32.0 27.0 80 83.8 80.8 88.8 53.5 124.0 112.0 120.0 116.0 26.0 33.0 28.0 85 88.8 84.6 94.2 56.5 131.8 119.0 127.5 123.3 27.0 34.0 29.0 90 93.8 89.3 99.6 59.5 139.5 126.0 135.0 130.5 28.0 35.0 30.0 95 98.8 94.1 105.0 62.5 147.3 133.0 142.5 138.8 29.0 36.0 31.0 100 103.8 98.8 110.4 65.5 155.0 140.0 150.0 145.0 30.0 37.0 32.0 Volume 3,000 4,500 8,000 9,000 5,000 3,000 5,000 5,000 - - - Notes: 1. Figures are to nearest decimal place. 2. All costs are included except typing. 3. The volume is the number of copies per month on which the figures are based. They will not hold good for other volumes, or for other organizations. Based on manufacturers' published figures to May 1974. 32 MANUFACTURERS AND DISTRIBUTORS ADDRESSES Addressograph-Multigraph Ltd, Itek Ltd, Mayland Avenue, 6 Paul Street, Hemel Hempstead, London EC2 4JH Herts Kalle AG, ADM Business Machines Ltd (Ordina), Wiesbaden-Bielrich, Windmill Road, Fed. Rep. Germany Sunbury-on-Thames, Middlesex Kodak Ltd, Kodak House, Agfa-Gevaert Ltd, Hemel Hempstead, Brentford, Herts Middlesex Minnesota Mining & Manufacturing Co. (3M) Ltd, George Anson Ltd (Minolta), Wigmore Street, 255-259 High Road, London W.l Ilford, Essex Nashua-Copycat Ltd, Greycoat Place, Antex Ltd, London S.W.I 184 Kennington Park Road, London S.E.I 1 NIG-Banda Ltd, Colchester, Apeco Ltd, Essex 231/237 Cambridge Heath Road, London E.2 Offrex Ltd, Stephen Street, Bell & Howell Ltd,, London W1A 1EA Winchester Works, Chertsey Road, Ozalid Ltd, Twickenham, Langston Road, Middlesex Loughton, Essex Bexford Ltd, Brantham, Pitney-Bowes Ltd, Manningtree, The Pinnacles, Essex Elizabeth Way, Harlow, A.B.Dick Co., Essex 3 Warple Way, Acton, Rank-Xerox Ltd, London W3 8BR Euston Road, London N.W.I GAF Ltd, 268 North Street, Remington-Rand Corporation Ltd, Romford, 65 Holborn Viaduct, Essex RM1 4QH London E.C.I Gestetner Ltd, Ricoh Ltd, Tottenham, Schipol Centrum, London N.17 Holland Harper & Tunstall Ltd, Roneo-Vickers Ltd, Letto Works, Lansdowne Road, Wellingborough, Croydon CR9 2HA, Northants Surrey IBM Corporation Ltd, Rotaprint Ltd, 389 Chiswick High Road, Honeypot Lane, London W.4 London N.W.9 Ilford Ltd, SCM Ltd, Ilford, 248/250 Tottenham Court Road, Essex London W1P OBE 33 Scott-Graphics Ltd, Liege, Belgium Solicitors Law Stationery Society, Oyez House, Breams Buildings, Fetter Lane, London E.C.4 Vader Grinten, Venlo, Holland REPORT DOCUMENTATION PAGE 1.Recipient's Reference 2. Originator's Reference 3. Further Reference 4. Security Classification of Document AGARD-AG-199 UNCLASSIFIED 5. Originator Advisory Group for Aerospace Research and Development North Atlantic Treaty Organization 7 rue Ancelle, 92200 Neuilly sur Seine, France 6. Title A Guide to Reprographic Processes For the Small User 7. Presented at 8. Authors) 9. Date T. Hampshire January 1975 10. Author's Address 11.Pages The National Reprographic Centre for Document 37 ation. The Hatfield Polytechnic. 12. Distribution Statement This document is distributed in accordance with AGARD policies and regulations, which are outlined on the Outside Back Covers of all AGARD publications. 13. Key words/Descriptors Printing 14.UDC Reprography Photomicrography Reproduction (copying) Cost comparison 681.62:778.1:778.31 Photocopying Reviews 15. Abstract The report provides detailed information on the various reprographic processes and systems available. The information is divided into the three main areas of reprography: — Photocopying Duplicating and Printing Micrographics In general terms the method of operation of the processes is provided and the various characteristics and application suitability are given after each process explanation, a summary chart is included in the Photocopying section. Mention is made of the required operator skills and comparative costings are provided for the Photocopying, Duplicating and Printing sections. In general the equipment illustrations are intended to show type rather than specific company's product. Therefore a list of major international manufacturers of equipment is included after each section to provide a guide from where specific information can be ob tained. AGARDograph No. 199 AGARD-AG-199 AGARDograph No. 199 AGARD-AG-199 Advisory Group for Aerospace Research and 681.62:778.1:778.31 Advisory Group for Aerospace Research and 681.62:778.1:778.31 Development, NATO Development, NATO A GUIDE TO REPROGRAPHIC PROCESSES Reprography A GUIDE TO REPROGRAPHIC PROCESSES Reprography FOR THE SMALL USER Reproduction (copying) FOR THE SMALL USER Reproduction (copying) T. Hampshire Photocopying T. Hampshire Photocopying Published January 1975 Printing Published January 1975 Printing 37 pages Photomicrography 37 pages Photomicrography Cost comparison Cost comparison The report provides detailed information on the various Reviews The report provides detailed information on the various Reviews reprographic processes and systems available. The in reprographic processes and systems available. The in formation is divided into the three main areas of formation is divided into the three main areas of reprography:- reprography: — Photocopying Photocopying Duplicating and Printing Duplicating and Printing Micrographs Micrographs P.T.O. P.T.O. AGARDograph No. 199 AGARD-AG-199 AGARDograph No. 199 AGARD-AG-199 Advisory Group for Aerospace Research and 681.62:778.1:778.31 Advisory Group for Aerospace Research and 681.62:778.1:778.31 Development, NATO Development, NATO A GUIDE TO REPROGRAPHIC PROCESSES Reprography A GUIDE TO REPROGRAPHIC PROCESSES Reprography FOR THE SMALL USER Reproduction (copying) FOR THE SMALL USER Reproduction (copying) T. Hampshire Photocopying T. Hampshire Photocopying Published January 1975 Printing Published January 1975 Printing 37 pages Photomicrography 37 pages Photomicrography Cost comparison Cost comparison The report provides detailed information on the various Reviews The report provides detailed information on the various Reviews reprographic processes and systems available. The in reprographic procesess and systems available. The in formation is divided into the three main areas of formation is divided into the three main areas of reprography:- reprography:- Photocopying Photocopying Duplicating and Printing Duplicating and Printing Micrographs Micrographs P.T.O. P.T.O. In general terms the method of operation of the processes is provided and the various In general terms the method of operation of the processes is provided and the various characteristics and application suitability are given after each process explanation, a characteristics and application suitability are given after each process explanation, a summary chart is included in the Photocopying section. summary chart is included in the Photocopying section. Mention is made of the required operator skills and comparative costings are provided Mention is made of the required operator skills and comparative costings are provided for the Photocopying, Duplicating and Printing sections. for the Photocopying, Duplicating and Printing sections. In general the equipment illustrations are intended to show type rather than specific In general the equipment illustrations are intended to show type rather than specific company's product. Therefore a list of major international manufacturers of equip company's product. Therefore a list of major international manufacturers of equip ment is included after each section to provide a guide from where specific information ment is included after each section to provide a guide from where specific information can be obtained. can be obtained. This report was prepared at the request of the Technical Information Panel of AGARD This report was prepared at the request of the Technical Information Panel of AGARD In general terms the method of operation of the processes is provided and the various In general terms the method of operation of the processes is provided and the various characteristics and application suitability are given after each process explanation, a characteristics and application suitability are given after each process explanation, a summary chart is included in the Photocopying section. summary chart is included in the Photocopying section. Mention is made of the required operator skills and comparative costings are provided Mention is made of the required operator skills and comparative costings are provided for the Photocopying, Duplicating and Printing sections. for the Photocopying, Duplicating and Printing sections. In general the equipment illustrations are intended to show type rather than specific In general the equipment illustrations are intended to show type rather than specific company's product. Therefore a list of major international manufacturers of equip company's product. Therefore a list of major international manufacturers of equip ment is included after each section to provide a guide from where specific information ment is included after each section to provide a guide from where specific information can be obtained. can be obtained. 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