Sheep, Goatskins Vellum--Calf Skins

Paper

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Paper Dr. Linda M. Perry

First writing surfaces

Animal skins Parchment--sheep, goatskins Vellum--calf skins. Finer quality than parchment. Long-lasting

Paper

Paper--A matted web of cellulose fibers. Almost any organic matter with fibrous structure. First developed in Egypt, 2500 B.C. Papyrus cross-laid and pounded with a stone. Modern papermaking Method first developed in China, first century A.D. Mulberry tree inner bark

Paper Making

Thru 18th century: By hand, fibers of hemp, linen and cotton rags. Fourdrinier (Henry and Sealy) made first practical papermaking machine, 1804. Rags until 1840. 1840: Wood mechanical pulping. 1867: acid pulping. Not practical until 1900.

Paper Sources

Rag or cotton pulp Almost pure cellulose Strong durable Reclaimed pulp (recycled paper) Paper submitted to alkali solution to dissolve ink. Chemically reduced to pulp. Grasses, straw, bamboo, jute. Mechanical wood pulp for newspaper stock. Chemical wood pulp Acids or alkali remove gums, resins. Long-, variable- and short-fibered pulps determine paper strength and durability, bulk, opacity and smoothness.

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Papermaking (wood)

Digester Cleans wood chips by chemicals, temperature. Bleached with chloride of lime. Beater Frays walls and ends of fibers. Beaten in water so they mesh and "felt." While in beater, materials added to pulp Sizing--Reduces moisture penetration, prevents fuzzing, gives hardness to paper (like starch). Blotting paper is unsized; Newsprint is slack-sized for fast ink-penetration; Writing, litho and offset stock are hard-sized to bind fibers and prevent absorption.

Fillers--Clay, talc, etc., fill spaces between fibers. Increases density, opacity, smoothness. Clay readily accepts polishing. Dyes--Color paper Alum--Weak acidifying agent to hold sizing & dye on fibers. Jordan--Pulp with additives beat again to reduce fibers to more uniform length.

Pulp now ready for wet end of papermaking machine: Fourdrinier section

Papermaking machine

Fourdrinier section Treated "stock" or pulp: 1% pulp, 99% water. Forced through tiny straining slots onto finely woven wire mesh. Wire mesh is a moving, endless screen, constantly vibrating. Interweaves, mats fibers. Fibers tend to flow lengthwise. Directional tendency is grain. Paper tears, folds most easily with the grain.

Dandy roll applies first surface pressure to top of paper. Used for watermarking. http://lindaperry.us/nm3217/paper.htm[10/15/12 8:31:57 AM] Paper

Watermark: A distinctive design; usually imprint of manufacturer’s name. Becomes an integral part of paper. Design formed with wire and attached to dandy roll, which impresses it into the wet paper.

The paper is formed into continuous roll, or Web is strong enough without screen web. to pass into press section of machine. Web is picked up by continuous strip of wool felt. Felt carries it through presses, multiple pressing and smoothing rollers. Top surface of the paper is felt side. Accepts printing better. Bottom surface is wire side.

From the presses, the paper moves unsupported to the drying section. Last step is calendering Calendering--Stack of 5 to 9 rollers incorporated into the dry end. For ironing and smoothing. Adds to gloss of finish. All paper known as machine-finished (wood paper)

Out of machine

Supercalendering Extra step outside papermaking machine Used for magazines and booklets. Finished by stack of calender rolls.

Coated stock (art paper) Smooth, shiny or mat finish. Web passes through vat with coating mixture. Coating emulsion adheres to paper. White china clay mixed with other agents. Gloss produced by supercalendering. Retains more ink on surface. More brilliant, denser color, so best for color pictures.

Definitions

Ream--500 sheets Basis size--Standard size of given paper grade. The size in which paper is normally and most conveniently produced. Basis weight--Weight of ream in basis size. 500 sheets of 25" x 38" at 70 lbs. = basis 70 (63.5 cm x 203.2 cm at 31.75k, or 105.35 grams per square meter [gsm]) Individual sheet is 70-lb. stock, or substance 70 Caliper thickness--Heavy stock, measured with micrometer.

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Major Classifications:

Book stock--25" x 38" (63.5 cm x 203.2 cm) From 45 to 120 lb. (20.41 to 54.43 k) Writing stock--17" x 22" (43.18 cm x 55.88 cm) Bond papers from 9 to 24 lb. (4 k to 10,89 k) (60 to 90 gsm; 80 gsm close to 20 lb bond) Ledger papers from 24 to 40 lb. (10,89 k to 18.14 k) (90 to 150 gsm) Manifold (onion skin) 9 lb. (4k) Cover stock--20" x 26" (50.8 cm x 66 cm) 50 and 80 lb. (22.68 k to 36.29 k ) 135.5 to 218.22 gsm) Heavier is measured in caliper thickness. International conversions for equivalent weights at http://www.paper- paper.com/weight.html.

Singapore conventions: Thin paper, 70-110 gsm (writing stock) Thick paper, 120-160 gsm (writing to cover stock) Super thick, 170-260 gsm (cover to caliper thickness) A5 128 gsm art paper (book stock, coated, glossy) A5 157 gsm art paper (cover stock, coated, glossy) A4 and A3, 128 gsm art paper (book stock, coated, glossy) A4 and A3, 157 gsm art paper (cover stock, coated, glossy)

Book Stocks

Antique finish--Similar to early printing. Machine finished. Eggshell Antique--Rough Finished with special felts Text--High grade antique. Quality books, brochures Vellum finish--Smoothest grade of antique. Paper vellum--Made from high quality rags for fine book editions and documents. Japan--Mulberry bark imitating classic vellum. Offset Stock--Smooth, uncoated book stock. Generally with a text or vellum finish. Sized on both sides to prevent curling. English finish (EF)--Nonglare, slightly roughened surface. Further development of machine finishing. Calendered or may be supercalendered. Coated stock (art paper) Ranges from enamel (super glossy) to dull (smooth, but without gloss). Matte-coated paper reproduces halftones well due to nonglare surface.

Writing Stocks

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Flat stock, bond stock, business paper, ledger stock, onion skin, carbonless paper.

Cover Stocks

Heavier, stronger, easier folding, wider variety of colors. Finishes: antique, coated, embossed, metallic laid or woven (impressed with pattern of the wire and/or dandy roll.) Pebble or ripple--surface pattern applied by rollers

Other paper stocks

Bristol bond--Heavy, stiff printing paper Postcards, display cards, brochures. Plain bristol, index bristol, coated bristol. Parchment paper--Waterproofed, extremely high grade of bond paper. India or Bible paper--Thin, delicate, made of vegetable fiber; used for engravings. Safety paper Duplex paper

Selecting paper

From printer or from paper house. Cost of paper has pronounced effect on the total cost of job. Consider: Proposed use--compatible with printing process & inks used. Strength, durability, foldability, permanence , and physical situations. Quality, surface and finish Weight, opacity. Size Match with press capacity and manner of impositions. Color Grain.

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