~ • Sawmilling . 19 May 1996
NZ FRI VALUE RECOVERY CENTRE
LouwVan Wyk
A specially made building with a strengthened • Remanufacturing: A cross-cut saw, straight-line concrete floor (photo front cover) designed for easy rip saw, clamp carrier for gluing, panel saw and bolt down and removal of a variety of processing data logging equipment have been installed. It is machinery has been constructed on the NZ FRI intended to have defect scanning equipment in Campus. This facility houses equipment required to place in the near future for speeding up defect do research into the following areas important to mapping of random width boards. Such data are adding value during the processing of radiata pine: presently obtained by manual measurement of defect coordinates (digitising). The data will be used to simulate ripping, cross-cutting, and •Log and lumber scanning: Precision conveyors defecting. After simulation and optimisation, slabs and laser scanners have been installed in the can be cut into component blanks and laminated centre to measure log, flitch and lumber profiles. into panels and joinery components for further These systems are being used to develop research purposes, eg. improving stability. algorithms to grade logs on the basis of external shape features. Transducers can be added to detect • Machine evaluation: The centre has been designed and record defect types and positions. to enable a wide range of machine types to be evaluated and tested while processing a range of • Lumber and saw inspection system: Lasers, video timber qualities, species and moisture contents. cameras, and displacement transducers have been installed in precision mountings. Extensive use is • Monitoring Energy Efficiency: ECNZ will provide made of virtual instrumentation software which the centre with equipment which can measure and enables users to programme personal computers record energy consumption by both the cutter and to perform a much wider range of data logging the drive motors. This information is of and analysis functions than is possible with importance when evaluating machinery or doing traditional equipment such as oscilloscopes. The machining trials, as the energy consumption can equipment can measure and analyse sawing be influenced by factors such as cutting angles, accuracy, surface roughness, tool cutting angles, wood density, moisture content, resin and machining precision. accumulation and tool tip wear.
NEW STAFF
John Turner
We're on the gain. Since October three staff have Development manager with TRADA Technology moved on but five new staff have started. Ltd. James' stay was all too brief, but much was Serge Fortin (Sawmilling group) has resigned and packed into it, particularly his management of taken time out to see NZ. Serge made considerable developments in the wood preservation process contribution in the remanufacturering field with his laboratory and enthusiasm on soccer fields and trout research into edge gluing, component recovery streams. potential from random width radiata, and technical support to the industry. Craig Trelaor (Wood On the input side we have: Quality group) has moved over to the Forestry John Roper, joined Wood Processing to take on Corporation to use his organisational skills and responcibilities for alternative species processing work with their Resource Quality Analyst team and research (i.e., species other than radiata & Douglas James Pendlebury (Preservation) has moved back to fir). Many of you will know him from his 20 years in Britain to to take up an appointment as Business the industry as forester, marketer, consultant, sawmill manager, and briefly (10 years ago) at process engineering. He also joined the Sawmilling NZ FRI in research liaison. group and is presently involved with a component recovery project and looking at modelling stability Peter Bayne, a recent graduate from Massey in engineered wood products. University with a degree in Computer Systems Engineering. He is working for us in the Sawmilling Rado Gazo, another! recent graduate, PhD,.from group using his skills on computer diagnostics for Mississipi State University (Forest Products, assessing sawing variation. Industrial Engineering) He has joined the Sawmilling group for an initial 4 months working Scott Mitchell, also a recent graduate, from on a remanufacturing project, where he is applying Canterbury University, with a Chemical Engineering his skills in industrial engineering methods, using degree majoring in process control and wood computer simulation to investigate component recovery from random width boards.
Ben Carpenter, who joined the Wood Protection group, as a technician trainee with Robin Wakeling. Ben was an electrical apprentice for some years, skills which no doubt will be put to occasional use. But has always been interested in science, when he has had time to spare from working on his car, skiing, and salt water fishing. Left to right, Back - Scott Mitchell, Rado Gazo, John Roper Front - Ben Carpenter, Peter Bayne
STABILITY OF RADIATA PINE
Dave Cown
Resource Characteristics microfibril angles, compression wood) several of which contribute to distortion and instability. The Distortion is a major cause of downgrade in sawn extent of juvenile wood is not universally agreed lumber, leading to reduced sawmilling profitability since each characteristic varies in a different fashion (affecting some 10% of sawn volume). Instability in within the tree stem. It is generally considered that service gives a poor image for wood in general and the first 5-10 growth rings from the pith in radiata radiata in particular. For radiata Juvenile wood is the pine are juvenile wood. main reason for this situation, and can comprise some 50% of the stem volume of managed pine Distortion and Instability plantations. Juvenile wood is a widely recognised but poorly defined feature of fast-grown softwoods. Contributing Factors-Wood Properties: It exhibits a number of characteristic properties (low Major Shrinkage; spiral grain; ring curvature wood density, low latewood %, short trachieds, wide Minor Grain distortion; microfibril angle; rings, tight ring curvature, high spiral grain, high compression wood Instability can be serious in the juvenile wood zone Contributing factors- Processing: where ring curvature, spiral grain and microfibril Major Drying method angle are high. Minor Sawing variation
Differential shrinkage (radial; tangential; longitud Generally if wood is dried to the correct "target" MC inal) is inevitable in all species, and radiata has and machined, it will not change dimension again "moderate" shrinkage, similar to many other unless the MC changes. It is critical to aim for the commercial softwoods. All woods change appropriate target MC. When this is uncertain, a dimensions with moisture content changes below nominal 12% is often used as a good average MC. the "fibre saturation point"( 30%). Other things being equal, normal shrinkage does not result in Drying method is also critical. HT drying (with excessive instability, only a change in the restraint) is not only fast, but also reduces the ability dimensions of the lumber. "Instability" usually of the wood to repond to moisture changes, thus it refers to the more serious longitudinal shape stabilises the wood to a large degree compared to changes - twist, crook, bow. drying at lower temperatures. However there is evidence that accelerated drying (>80°C) causes Shrinkage and wood density are correlated - often drying stresses which are not completely removed higher density woods shrink more. This is the case in normal steam conditioning. The residual stresses in radiata pine where tangential and radial result in delayed movement in reprocessing. shrinkage increase from the pith to the bark. Pressurised drying/steaming may better plasticise Longitudinal shrinkage (closely related to micro the lumber and yield reductions in warp and fibril angle) decreases from pith to bark, and is residual stress. usually insignificant outside the first few growth rings. Sawing variation contributes to distortion if it is significant enough to allow the lumber to move in Spiral grain is a major cause of instability, as the fillet during drying. wood fibres are oriented at an angle to the axis of the lumber. Spiral grain in radiata is a feature of the Recommendations juvenile wood (pith to rings 5 - 10). Shrinkage and spiral grain combined lead to instability. The grain Short Term: angles tend to increase with height in the stem, so 1. Understand juvenile wood characteristics that juvenile wood from toplogs has a more 2. A void juvenile wood in critical situations where pronounced spiral grain than juvenile wood from RH fluctuates the butt logs. Research studies have confirmed a 3. Use HT drying with restraint close association between stand age and drying 4. With structural timber, promote the use of dry distortion - logs from young thinnings (mainly framing juvenile wood) sawn to 100x50 showed up to 50% 5. Pressure drying/ steaming rejection according to the NZ grading rules. Long term: Even with increasing shrinkage from pith to bark, 1. Study wood microstructure in relation to distortion decreases as the spiral grain angles distortion/ instability reduce. However, compression wood also exhibits 2. Develop sawing and drying methods to higher longitudinal shrinkage, and can cause minimise distortion distortion wherever it occurs. Compression wood is 3. Select genotypes with better wood quality thought to be one of the main contributors to spring 4. Design processes and products to minimise in full length mouldings etc. impact of juvenile wood
VIDEO SAW TOOTH INSPECTION TOOL
Armas Jappinen
As part of a research project set up to identify major The system can for example be used to measure side causes of sawing variation in New Zealand clearance and angle, tooth point line (all teeth in the sawmills, NZ FRl has developed its own saw tooth same line), sharpness and tooth surface finish. The inspection system. The system uses a video measurements on band saws are taken from the top microscope and the "Video Trace" software to allow or side of the tooth, and on circular saws measure size and angle measurements to be taken using a ments can also be taken from the front of the tooth. "mouse" on a computer monitor. The image on the screen allows observation of the saw alignment while the saw is slowly rotated. The image can be frozen to allow measurements to be taken. A macro (computer routine) has been written which records the measure ments in a data file.
The accuracy of the current system is about 0.05 mm which typically is also about the tolerance for measured saw grinding param eters. The resolution of the system is about 100 pixels/mm (pixel O.Olmm) but the repeatability depends on An image of a circular saw tooth measured at the TITC in Rotorua, indicating the skill of the operator possible measurements done by drawing lines with the mouse on screen, after using the "mouse" for which the software calculates the values. measurements on screen. The accuracy of the system can be further improved by using a camera recent improvements in small data aquisition cards with higher resolution and by using an automatic for "portable note books" to make the system more image processing program. compact. At present the system is set up in the new Value Recovery Centre at NZ FRI where it is also A future development, to enable field data to be used for other applications, such as, measurements collected at mills around NZ, is to make use of of finger joint size and quality.
CLEARWOOD FROM PRUNED RADIATA PINES
Don McConchie
Many in the industry, (both growers and processors) characteristics recorded from clearwood (knot free are familiar with the Pruned Log Index (PLI) which wood) in a number of locations throughout New documents the volume of knot-free wood available Zealand. The initial concern centred on the in pruned logs. This index reflects the relationship Canterbury Plains with sites in Marlborough and between the knotty core and the small end diameter the Southern Wairarapa now included. Other of the log, and is often used to indicate quality and examples, with high levels of resin pockets value. documented, include localised sites in Hawkes Bay and in the Bay of Plenty. There are indications From a wood quality perspective additional features that other areas, particularly those that are can have a significant impact on the appearance and exposed to wind or prone to dry conditions may stability of products, and hence on the value implied experience this problem. by PLI. Recent NZ FRI studies and a significant number of inquiries from the industry indicate that the wood quality considerations are becoming • Needle fleck: Needle fleck is a blemish resulting increasingly important. These additional wood from the retention of needles on the stem. Early quality concerns are: pruning procedure did not always recognise the impact of stem needles which were often left to • Resin pockets and streaks: Early concerns about grow. Recently some markets have identified the the impact of resin pockets have proved valid, resultant blemishes as unacceptable in high value with high levels of degrade due to these products. • Spiral grain: The normal pattern of spiral grain more widely distributed around the within trees shows that grain angles decrease from circumference. The significance of the pith to the bark, and increase with increasing compression wood relates to its tendency to high height in the tree. Considerable variation between longitudinal shrinkage, reduced strength and trees has been documented. Grain angles >5° have poorer stability. a marked impact on distortion during drying (twist), and reduce strength properties. The • Juvenile wood: The drive to maintain a minimum considerable between-tree variation and minimal knotty core allows the production of knot free knotty cores can result in clearwood containing lumber within the juvenile wood zone. The angles above 5°, leading to drying distortion and juvenile wood of most pine species is well instability. documented as being the weakest and least stable wood within the tree. Among other properties this • Compression wood: Research indicates two main zone has the highest levels of spiral grain and contributors to the formation of compression longitudinal shrinkage, and can also have high wood. The first results from the normal levels of compression wood. These properties, mechanism by which leaning trees right individually or combined, can have a serious themselves. Compression wood in these cases is effect on processing and stability. produced on the underside of the lean and forms a concentrated zone.The second contributor is found in rapidly growing trees and is considered It is important to consider the potential effect of to be linked to an over-production of growth these additional wood quality variables when hormones. This form of compression wood is determining clearwood value.
AUSTRALIA PINE PRODUCERS INTRODUCE MGP PINE TO THE MARKET
Bryan Walford
MGPproduct properties are large and, most importantly, the stiffness values (modulus of elasticity or "E" values) Members of the Pine Australia group now market have increased. The following tables compares the their machine-graded radiata pine as MGP grades. F-grade and MGP-grade properties MGP stands for "Machine Graded Pine" - nothing mysterious in that. Grades previously known as F5, Characteristic strength and stiffness values (MPa) F8 and Fll are now called MGPlO, MGP12 and Bendinq Tension Shear Compression Stiffness MGP15 respectively. Why the change? The same MGP10 16.2 8.9 5.0 23.6 10,000 grading machines with the same settings are used so F5 16.2 8.2 1.8 12.1 6,900 what's different? Ratio (MG/F) 1.0 1.08 2.78 1.95 1.45 MGP12 28.0 15.0 6.5 28.9 12,700 What's different? F8 25.4 13.0 2.5 19.5 9,100 Ratio (MG/F) 1.1 1.15 2.6 1.48 1.4 What has happened is that Pine Australia MGP15 41.3 22.7 9.1 35.4 15,200 commissioned a huge research project to do an in F11 32.5 16.6 3.1 24.8 10,500 grade evaluation of their product, testing two Ratio (MG/F) 1.27 1.37 2.94 1.43 1.45 species, nine sizes, three grades and four strength properties - more than 10,000 tests. They found that their timber has higher stiffness and some higher Market advantage strength properties than had been assigned to this timber under the F-grade system (which was Unless NZ producers can prove that their timber has derived largely from hardwood properties). Under equal properties they will be at a disadvantage in the Australian timber design code, AS 1720, a the market place. Some in-grade evaluation (two designer may use the strength properties assigned sizes and two grades) of NZ-produced MSG radiata under the F-grade system or strength properties has been done at FRI and it shows that by and large established by in-grade testing. In-grade testing is the NZ product will match these properties - some simply the testing of the timber in the sizes and mills might have to tweak their machines up a bit. grades as normally marketed rather than testing Producers using visual grading might be stuck with small defect-free samples of wood and applying the F-grade system unless they can devise grading grade factors to the measured strengths based on rules that will sort out the timber according to grading rules. Some of the changes in strength stiffness better than the present grading rules do. A COMPARISON BETWEEN ACTUAL GRADE RECOVERY AND PREDICTED GRADE RECOVERY FOR YOUNG UNPRUNED SAWLOGS FROM THREE CENTRAL NORTH ISLAND LOCATIONS
Don Mcconchie
The following article is a brief summary of findings at a young age under some circumstances - high from three recent sawing trials. Further information density, smaller branches. on any of these studies is available from me. Table 3 -Actual and predicted grade recovery(%) Samples of unpruned saw logs were obtained from the young stands presented in Table 1. They were Stand N.Z. visual grade Machine grade measured in detail prior to sawing, then processed l.D. 1F 2F Box F5+ Note: Stand A. is a forest plantation site planted with 'climbing select' stock and B & C are fertile ex pasture sites planted with '850' seed orchard stock. In order to predict grade recovery for a batch of logs using the NZ FRI model SAWMOD, defined log characteristics must be accurately measured. Log data for the 3 studies is presented in Table 2 and the actual and predicted grade recoveries are compared in Table 3. Table 2 - Log characteristics Stand No. of SEO BIX* lnternode Density l.D. Logs cm cm Index** kg/m3 A 47 32 4.2 0.35 400 B 48 39 6.4 0.16 350 c 31 31 6.5 0.10 341 • average of the largest branch/quartile ••The sum of internode lengths >0 .6m as a proportion of log length Table 3 shows that the current grade prediction model SAWMOD can accurately predict both visual and machine grade recoveries for young stands Trees on fertile site established in existing forest situations, managed following a more conservative regime with regard to stocking i.e., Stand A. Stand A also indicates that Stands B and C, established on fertile ex-pasture excellent machine grade recoveries can be achieved sites and managed for clearwood production with the associated reduction in stocking, both show characteristics, including both branch size and the large discrepancies between actual and predicted distribution of internodes. The results suggest that grade recoveries. Both these studies showed the branching characteristics produced on these relatively low wood density for this age (in relation fertile sites may not be adequately described by our to the '850' seed source), high levels of spiral grain, current standard of measurement. The increased (average spiral grain exceeding 5° within 12 growth number of whorls indicated by the reduced rings from the pith at Tikitere) and higher than what internode index and increase in the number of might be considered normal levels of compression branches/log prevented upgrading to Cuttings wood, particularly in the faster-grown logs. The grades. Resin pockets were also a feature at both spiral grain resulted in increased degrade due to these locations, and were observed in the clearwood twist, and the compression wood an increase in from the pruned butt logs as well as in the degrade due to crook. Neither of these types of unpruned portion of the tree. The levels of spiral drying degrade is taken into account in the grain and compression wood recorded can be predicted grade recoveries, and this accounts for expected to reduce the stability of a portion of the part of the discrepancy between actual and clearwood produced in the butt logs and in the short predicted grade recoveries shown above. Although 'clear cuttings' available from the unpruned logs. the data are not presented in this article, Stand A showed particularly low levels of spiral grain and Conclusions: consequently no lumber was degraded due to excessive twist. The occurrence of compression • Fertile sites give poorer grade recovery. wood was also minimal with no associated degrade • SA WMOD works well for some regimes, due to crook. particularly those with more conservative silviculture. The genetic stock, fertile site and wide spacing • SA WMOD needs to be modified to better cater have also had a significant effect on branch for fertile sites and young logs. HOW ARE NEW ZEALAND SAWMILLS DOING? John Roper The Ministry of Forestry has recently revised rising from 41.5% to 54.0% in just over 20 years. sawmill conversion figures and round wood log This means that for every 1 million m3 of plantation usage back to 1990. logs cut there is an extra 125,000 m3 of sawn lumber available. The figures are based on the annual returns of sawmill production and conversion as returned by NZ Sawmill output and conversion the individual mills. These are weighted to give the national average which is being reported here. Year(s) New Zealand Sawmills Sawn Output Ended Sawn conversion (mill.m3) 31 March (%)1 1. Increasing conversion 1960-1974 44.0 1.7 (av.) The revised MOF figures indicate a trend in (plantation logs only 41 .5%) increasing production and conversion efficiency as 1975-1989 46.0 2.1 (av.) mills upgrade equipment to make better use of the 1990 49.3 2.1 available log supply. 1991 50.0 2.2 1992 50.5 2.3 Prior to 1975 significant percentages of logs sawn in 1993 51 .3 2.6 NewZealand sawmills were high quality native logs. 1994 52.9 2.8 These gave higher conversions than the exotic logs 1995 54.0 2.9 of the day. m3 (sawn output) 1 Sawn conversion % = 3 x 100% Since 1975 the differences in conversion have m (log output) become less significant and by 1995 indigenous sawn lumber had dwindled to comprise only 1.5% This 125,000 m3 (sawn) is equivalent to a 30% gain in of the total sawmill output. lumber yield for the same amount of log input. But even this will probably not be sufficient to guarantee Therefore the improvement in conversion is even the continued growth and profitability of the more dramatic in the plantation (exotic) sawmills, industry. Effect of increased efficiency of exotic sawmills • Relatively high export log prices and good demand; Log input Conv. Efficiency Sawn Output • A "market opportunity pricing" approach from m3 % (year) m3 (sawn) NZ Forest Owners benchmarking domestic sales 1,000,000 41.5(1974) 415,000 to achievable export prices; 1,000 ,000 54.0 (1995) 540 ,000 • A lack of profitable markets for New Zealand lumber at these log prices and current sawmill Increased yield due to 125,000 m3 conversions; conversion gain1974-1995. per million m3 log input • A lack of confidence for new investment in plant in New Zealand arising from this; 2. Competition for logs. • A very volatile log and lumber price over the last few years, leading to opportunistic marketing and Sawmills have not maintained their importance as industry instability; markets for logs from New Zealand's rapidly • Tariffs which discourage the import of sawn expanding forest harvest. In fact over the last 45 lumber from New Zealand but favour other years this decline has been remarkable. New countries and/ or the importation of logs. Zealand sawmill usage of 95% of all logs harvested in the early 1950s has now dropped to 33% of total 3. The Future harvest. Forward projections of roundwood harvest vary, but Roundwood mill. m3 per annum it is possible that the increase of nearly 7 million m3 over the last 7 years could continue until 2010 at a Year Total Harvest Sawmill Logs Export Logs similar rate, reaching a harvest level of some 30 mill.m3 mill.m3 (%of total) mill.m3 (%of total) million m3 per annum. 1988 9.7 3.8 (41) 0.7 (7) 1989 10.6 4.0 (39) 1.4 (13) If this scenario is played out then effectively the 1990 11.7 4.1 (37) 1.9 (17) roundwood harvest will have gone from 10 million 1991 13.7 4.4 (33) 3.1 (22) m3 (1989) to 30 million m3 (2010) in just over 20 1992 14.1 4.4 (32) 3.6 (25) 1993 14.9 5.0 (34) 4.5 (30) years. 1994 15.1 5.2 (35) 4.3 (28) 1995 16.4 5.3 (33) 4.8 (30) • Seven years into (and one third of the way through) this rapid change in New Zealand the sawmilling industry seems to be at least holding After a continuing rapid decline until the early 1990s it's own. this "share" used by sawmills has stabilised at • Logs from the heavier thinning regimes of the around 33% of the rapidly expanding harvest. 1970s are now entering New Zealand sawmills giving lower grade yields in conventional The really big gain has been in percentage of total structural sizes. harvest exported as logs, rising from a level of 7% • There is a marketing challenge to seek (relatively constant throughout the 1980s) to 30% of appropriate markets for this lumber. .total harvest in 1995. • With shorter rotation ages (now commonly less than 30 years) and reduced piece size in New Moreover, figures for late 1995 and early 1996 Zealand's plantation forests, the future challenge indicate that log exports may actually exceed the for sawmillers will be to maintain conversion usage of saw logs in New Zealand for the 1996 year gains and endeavour to increase them with good for the first time ever. The reasons for this rapid management and control as well as appropriate acceleration of log exports are many and varied. technology. • The proposed "Conversion Multiclient" is to The arguments are hotly debated in the New assist sawmill managers to meet these challenges Zealand industry, but among the reasons are: with targeted research projects. FERTILE FARM SITES - LOG QUALITY SURVEY John Roper NZ FRI Wood Processing Division is interested in will be conducting a survey relating to the above obtaining current utilisation information for logs shortly. grown on highly fertile farm sites. We would like to learn from the experiences of those who have processed logs from fertile sites and would like If you have any immediate responses you wish to some feedback on how the logs affect mill relate please contact: productivity, how they meet grade expectations, recovery expectations, and customer acceptance in John Roper, regard to appearance, strength, and stability. NZ Forest Research Institute, Phone: (07) 347-5477, If you have any experience processing these logs Fax: (07) 347-9380 please accumulate the details. NZ FRI Wood Quality email: [email protected] SAWMILL CONVERSION MULTICLIENT NZ FRI' s Wood Processing group has run a cutting patterns. successful kiln drying multiclient for some years. • What do they really do for conversion? This combines industry funding with government • Can you afford one, or afford not to have one? funding to target particular areas of concern to industry. 2. Log grade evaluations. • Is the "new crop" living up to expectations - The new "Value Recovery" initiative has partici good or bad? pation from the major forestry companies, but a • What are the sawn grade yields? large number of independently owned sawmills do • What markets best suit this lumber? not take part in this programme. John Roper, who has recently joined the Wood To better meet the research and development needs Processing group after 6 years as a sawmill of this group a "conversion multiclient" is proposed. manager, will be heading this project and will be in contact with likely participants shortly, or you may The initial projects proposed are: contact him at NZ FRI to indicate your interest in 1. Evaluation of carriage log scanners and optimised joining. ~ ~Wood Preservation ·' ' '·.i Mick Hedley Preservative treatment of perishable timbers, Inter-tree variability in natural durability of three especially softwoods, was developed as an Eucalyptus species. alternative to use of naturally durable timber species. From several quarters, there have been calls Species Number of specimens remaining (and average life) for a reversal of this development by using Tree 1 Tree 2 Tree 3 Tree 4 Tree 5 plantation-grown naturally durable species as E. 5 0 3 0 2 pilularis alternatives to preservative treatment. (av. life ?yr) (av. life 5.7yr) E. 2 1 2 1 0 muellerana (av. life Byr) While this may seem a sensible approach for some E. 4 6 2 0 1 timber commodities, there are practical problems in globoidea (av. life 4 yr) profitably growing species of sufficient durability. However, there is also the problem that durability of any species can be variable, not only in wood within a tree, but also between trees of the same for utilisation; species. • E. pilularis has 10 specimens left from 3 different trees and the average life so far determined (from This is illustrated in results of an NZ FRI test in 2 trees) is 6.3 years. which 10 sa...'llples were cut from each of 5 different • E. muellerana has only 6 specimens left spread 19-year old trees (an age where within-tree evenly over 4 trees with an average life durability variability would be small) of Eucalyptus established from 1 tree of 8 years. pilularis, E. muellerana and E. globoidea; durable (but • E. globoidea has 13 specimens left, 10 of which are not highly) species amenable to plantation from 2 trees, but average life from 1 tree was only management in some parts of New Zealand. 4 years. Thus when advocating greater use of naturally The number of specimens remaining after 14 years' durable timber, within-species variability, which exposure in ground contact is shown in the table. will lead to inconsistencies in performance, must be weighed against the highly predictable and On the basis of this test to date, it would be difficult consistent performance of preservative treated to decide which of these species is the better option radiata pine. PROTECTION OF EXPORT LOGS FROM FUNGAL DEGRADE Robin Wakeling Industry estimates of loss of value to export logs problem. When a tree is felled and much of its bark caused by fungal degrade are in excess of $100 is removed by normal handling practice, it is immed million per annum. Current down-grading of logs iately susceptible to attack by sapstain, decay and affects the image of New Zealand radiata pine as a mould fungi. The rate of attack depends on the pre high value wood resource, and reduces the ability to vailing climatic conditions. Optimal conditions for expand into larger high value markets. This loss in germination of fungal spores and establishment and value will be greatly reduced through adoption of proliferation of their mycelium (a mass of hyphae, an integrated approach to control of fungal degrade. microscopic thread-like structures functionally similar to plant roots) depends on the fungal species Before addressing a route to prevention of fungal but in New Zealand temperatures of 24 - 27°C and degrade it is worth defining the nature of the relative humidities above 98% are optimal. If conditions for fungal growth are near optimal The nature of wood ensures that regions of high mould fungi tend to become established first and are relative humidity are common within the voids most commonly seen as green, blue or black present within the surface wood layers of a log, and discolourations on the surface of logs within 1 - 3 spores arriving in these zones are able to germinate days. Relative humidity is usually the controlling and become established. That is, there is no reliable factor that determines whether or not extensive correlation between the surface condition of logs mould growth will occur on logs. If the humidity and the extent of internal sapstain. Incipient decay remains high (>95%) mould growth will occur on of logs usually lags behind sapstain by about logs within a few days, over a fairly wide 2 weeks but rates of penetration into the log are temperature range (15 - 57°C). Relative humidity is similar. also the most important factor controlling growth of sapstain fungi on the surface of logs; this will also Exporters do not always understand what occur within a few days. Sapstain fungi common in constitutes unacceptable fungal degrade as New Zealand have optimal growth temperatures of perceived by the consumer, or how they handle the 26 - 28°C, but sapstain fungi capable of rapid growth wood upon arrival at the port of call. This at higher temperatures are common in tropical and knowledge is a necessary first step in establishing sub-tropical countries. the best approach to getting wood free of fungal degrade to the customer. For example the choice of The climatic conditions that promote rapid growth treatment and handling regime for logs to be of sapstain fungi into a log are different from those exported in the following two situations is different: that promote rapid growth on the surface. When a tree is felled the sapwood is saturated with water, (a) A customer who demands wood guaranteed to and oxygen tensions are too low for fungal growth be free of any fungal degrade and who in tum within the woody tissues. Growth into the log will can guarantee that timber will be processed not occur if moisture loss is prevented. This is the within two weeks of arrival. Timber will be principle behind ponding logs as the high moisture processed within 2 - 3 months of felling. content of the wood is maintained artificially, thus preventing sapstain. If logs are stored at very high (b) A customer who has the same expectations as (i) relative humidity (>98%) where the air is still (no but who is unable to process the timber quickly. wind) onset of sapstain will be very slow. For Timber is likely not to be processed within example logs stored under these conditions for 2 3 months and is often processed 4 - 6 months weeks have virtually no sapstain inside the log after felling. (beyond a depth of 3mm) whereas logs stored at 25°C, 75% RH, where air movement is not restricted, Since currently used antisapstain treatment cannot have extensive sapstain to a depth of 20 - 30 be guaranteed to be effective if logs are not centimetres (mean radial penetration rates = processed with 3 months it is inappropriate to 2 - 4mm/ day). Therefore the controlling factor for supply logs to type (b) customers. The current sapstain development in logs (not surface growth) is alternative should be to kiln dry the timber in New the rate at which moisture loss occurs. The greater Zealand. Type (a) customers can be supplied with the rate of moisture loss at ambient temperatures antisapstain-treated logs. and normal atmospheric pressures, the greater the rate of sapstain development. More specifically, the Antisapstain treatments are fungicides applied to greater the efficiency of water vapour loss occurring the surface of wood. Penetration into the wood is at the wood's surface, within a temperature range usually minimal and therfore the treatment that does not inhibit fungal growth, the greater the ostensibly provides an 'envelope of fungicide that rate of sapstain penetration. encapsulates the log'. The basic mode of action of fungicides varies according to their chemistry, but they can have a fungicidal effect, where the fungal Results of research at NZ FRl suggest that provided spore or mycelium is killed, and/ or a fungistatic temperatures do not exceed those suitable for fungal effect, where the fungal spore is prevented from growth, the wood will not dry rapidly enough to germination and growth but is not killed. Whatever prevent penetration of sapstain, to the entire depth the mode of action it is essential to deliver the of sapwood present at the rate of penetration fungicide to the wood's surface before fungi have observed. In fact the lower the relative humidity penetrated to a depth beyond the reach of the (40% RH was the lowest studied in the laboratory) fungicide. The timeframe in which logs must be and the greater the wind velocity, the greater was treated after felling to achieve this depends greatly the rate of sapstain penetration. Results showed on the prevailing climatic conditions and the that the sapstains Ophiostoma piceae and Diplodia pini method of log handling. As already discussed, do not require high relative humidity on the outside climatic conditions that promote rapid drying will to achieve rapid colonisation of wood within the log. also greatly accellerate the rate of sapstain penetration. Research at NZ FRI to determine between fungicide mobility and achieving correct maximum pre-treatment holding times, for a range threshold concentrations for fungitoxicity are crucial of storage conditions, is continuing. to effective antisapstain treatment of logs. The fungicide I wood I fungus I moisture interaction The maximum pre-treatment holding time is highly mechanisms that operate at the surface of logs is in dependent on the subsequent antisapstain some aspects very different from those which treatment. For example some fungicides in operate at the surface of sawn timber. Increasing antisapstain formulations 'fix' chemically to wood understand-ing of these mechanisms is the subject of very effectively and consequently treat only wood continuing research in the wood protection group. that was in direct contact with the treatment solution, since there is no significant diffusion into the surface wood layers to a depth of 1 - 3 The upper limit of fungal degrade in logs destined millimetres. Consequently if a sapstain fungus has for high value markets would ideally be zero. The already penetrated 1 - 2 mm the fungicide will be wood protection group currently uses a value of totally ineffective. less than 1 % mean surface cover of sapstain in boards as an upper acceptable limit during log trial Fungicides that are insoluble in water and are not assessments. This could equate to 10% of boards formulated in a way that promotes mobility, will having 10% fungal degrade or 100% of boards also only treat effectively at the point of contact. having 1 % degrade. Whilst this degree of sapstain may appear high, in general it would not be noticed by most handlers and consumers. However use of fungicides that are diffusible offers scope to 'arrest' sapstain fungus in the outer few millimetres. Sufficient fungicide must be applied to The Wood Protection group has adopted an the log surface to maintain fungicide concentration integrated approach to controlling fungal degrade of at threshold levels for effective fungitoxicity over the logs, the aim of which is to improve the reliability of entire diffusion zone. Achieving and correct balance control for log storage periods up to 3 months and to develop control systems that extend the protection period to 4 - 6 months. It is believed that the best approach to control is a combined antisapstain treatment that exploits: (i) Physical control methods, e.g. manipulating wood moisture content. (ii) Combined chemical treatment that provides an effective envelope of fungicide on the logs surface but also penetrates the surface layers, making the envelope more 'robust' and arresting fungal growth that has already become established. (iii) Use of specific biocontrol agents capable of forming an integral part of a dual treatment system. Biological control involves inoculating wood with a microorganism, that once established, prevents the growth of wood degrading fungi. Export logs AS 1604 - THE FINAL ACT? Mick Hedley SOURCE H3SW H3HW H4SW H4HW HSSW HSHW Way, way back in August 1988, a revision of Australian Standard AS mass/volume - kg of chemical/m3 wood 1604 "Preservative Treatment for mass/mass - gm/chemical/1 OOgm oven dry wood retention Sawn Timber" was circulated for i r-~J*r-&i'1$Jl8J ~ 10 AWPe 5/89 6.9 13.8 8.0 16.0 12.0 24.0 Where to now? 0.38 0.38 0.62 0.62 0.96 0.96 11 TM/6 8/89 6.9 13.8 8.0 16.0 16.0 24.0 The next stage is to use AS 1604 as a 0.38 0.38 0.62 0.62 0.96 0.96 basis for a joint AS/NZ Standard, with a target publication date by 12 TM/6 7/90 4.74 10.0 7.9 16.6 10.6 32.9 0.38 0.38 0.63 0.63 0.85 1.25 2000. The NZ Timber Preservation Council has appointed Mick Hedley . 13 UNKNOWN 5.6 10.4 9.3 19.2 10.6 32.9 of FRI and Jeanette Drysdale of 0.38 0.38 0.63 0.70 0.85 1.25 Koppers-Hickson to co-ordinate 14 TM/6 8/90 5.6 10.4 9.3 19.2 14.6 32.9 NZ's part of this exercise, with the 0.38 0.38 0.63 0.70 1.00 1.20 suggestion that two Australians from Committee TM/6 also be 15 AWPe 4/91 5.6 10.4 9.0 19.0 14.8 32.0 appointed to an informal committee 0.38 0.38 0.63 0.70 1.00 1.20 to get the ball rolling. 16 TM/6 12/94 5.6 10.4 9.0 19.0 14.8 32.0 0.38 0.38 0.63 0.70 1.00 1.20 There are still some fairly major discrepancies between the NZ and 17 TM/6 5/95 5.6 10.4 9.0 19.0 14.8 32.0 0.38 0.38 0.63 0.70 1.00 1.20 Australian Standards, mainly in heartwood penetration require 18 TM/6 10/95 N/A N/A N/A N/A N/A N/A ments; and composite products 0.38 0.38 0.63 0.70 1.00 1.20 (plywood and glue-laminated 1 '~., .., ,....., .... ,_ ..ii'GSU(:t "., ... ,,,, . "W ., ,.,.,,_ . ~.,_ .,,.,_.,,...... ~ •.. ..._.... "", "" '~"" ' '' "'"' ""'" ...... •_... - ,,,- ~" "" ""' 'w ·· ~w ~ · - -· ~' -;t " ''"""""'"''"""~~ ., • ..,_~~,.....,.,, """"~ · ~· , ····· beams) are not included in AS 1604 . .... :<=~-~* · ''*"~"""' • ""·'';~ ... : ,,:;..,:;;.._.,., ,, """~' -'" '" ~ '"'"''···""'l:t;·"··' ...... ~ .~ .... ., ...... :.. ... ;.;...... , ,,,_,,...;&;«;;-...... ~·,;;;:-...... w ...... :-: ~'""·--~·-·- .•.•..•.• ;..~ But we are optimistic of a successful 19 TM/6 02/96 N/A N/A N/A N/A N/A N/A outcome with resultant tangible 0.38 0.38 0.63 0.70 1.00 1.20 benefits to NZ exporters of treated MP 3604 N/A N/A N/A N/A N/A N/A timber to Australia . 0.37 0.37 0.72 0.72 0.95 1.73 i·-u ~m~,t~:: ·.::·\'~:·"'.'~""""~~1 ~ r...... ~ ... _..... ~,-':>'_ ,~~:"···· ._.. ..,... ..,,,...... ,, ..,, ... _,,..,..."" ... y ...... FO HE~~~-. : ~ .~/ c:.::~r1TUTE ~Wood Drying ~.:~:::_~-·~-· ____.j Issue No. 19 May 1996 UPDATE ON CURRENT DRYING RESEARCH PROJECTS Tony Haslett FRI/Industry Multiclient Drying Research Project Kiln Brown Stain (KBS) At the December meeting of this project Ian Simpson Bernhard Kreber has made good progress in this presented the results of an excellent study on the area and he recently reported to the first KBS project evaluation of four commercial in-line moisture meeting. To date Bernhard has investigated the meters (Wagner 683, Lignamat, Moisture Register chemistry of KBS, clonal differences in susceptibility Products, Elliott Bay Industries) and one hand-held to stain, the role of kiln temperature and wood capacitance (Wagner L612) and one hand-held moisture content on KBS and mechanical treatments resistance meter (Carrel and Carrel C201). He was to reduce KBS. Bernhard will soon be publishing his able to provide correction figures for 40 and 50 mm findings. thickness and compare the accuracy of each meter. I reported on the need for weights during cooling after HT drying. We are currently working on a Modelling of Drying project to determine the important silvicultural, wood quality and kiln schedule factors influencing Using a computer model of radiata pine drying we the stability of full length mouldings. The final topic are now able to predict drying time, overall me and for the current project is to determine the variation me gradient of single boards, and me variation in drying rate for wood from different areas of throughout a kiln stack, for a range of kiln schedules New Zealand and Australia, as well as wood from and lumber dimensions. The model has recently also different positions within the tree. been extended to include the drying of radiata veneer and is now being used to test the effect of We are currently canvassing the industry for their various drying strategies on gas consumption and suggestions on current drying technical issues and veneer me variation. We are using the lumber model these will be included in the new project commen to predict drying times of newly developed cing in July. If you have any concerns please contact schedules and it may be incorporated into Dryspec me and I will include these; I think much of the to assist with endpoint determination. Pang success of this project lies in selecting topics which Shusheng will prepare a detailed article on the are relevant to industry. Also in the near future I modelling for the next newsletter. will be contacting all companies involved in drying to offer them the opportunity to participate in the July project. If you require information on the Drying Endpoint Determination project group contact me. Determination of the drying endpoint is a critical Within-Ring Internal Checking area, and over the last two years Scott W astney and Steve Riley have made good progress. Evaluation of Rolf Booker has a PHD student working on a commercial capacitance-based system showed that fundamental aspects of cell wall structure and how there was limited potential to further improve the these could affect collapse and within-ring checking. system but a new resistance-based system is now Rolf and Prof. Ho-Yang Kang are also using acoustic being developed for commercial implementation. emission equipment to monitor the development of This work has been done in conjunction with the checks at a range of drying temperatures. Once they Windsor Engineering Group. NZ FRI and Industrial have determined the maximum safe kiln temper Research Limited\IRL) have also lodged a patent ature and the critical me below which no further application for a microwave-based endpoint system. checking occurs, they will optimise the final stage of The microwave system offers the advantages of the kiln schedule. All their work has been with being temperature (i.e., kiln schedule) independent lumber which has been prescreened and shown to and requiring no on-site calibration. We hope to be prone to checking. We hope to be able to release a commercialise the microwave technology within stepped schedule for drying check-prone lumber. 12months. NEW KILN DRYING STANDARD Tony Haslett Good progress has been made towards the lumber. Performance standards are now preferred, development of a new kiln drying standard. and these contain measurement of minimum acceptable quality with no reference to how the The move is timely, because NZS 632, the current producer meets the quality. New Zealand standard, was introduced in 1967 and is now largely out of date. More significantly, The group was able to take advantage of work done Australia has never had a kiln standard, the only on behalf of the Commission of European relevant document being the Pine Australia Communities by the European Drying Group, which standard for high temperature drying of heart-in had recently prepared a pilot standard. With studs. modifications, this will form the basis for the new joint Australasian standard. Representatives of drying researchers and sawmillers from New Zealand (including NZ FRI, Very briefly the key features of the proposed CHH and Windsor Engineering) and Australia standard are: therefore met recently to discuss the need. There • A table which, over a range of target moisture was strong support for the concept of a joint New contents and end use quality levels, defines the Zealand/ Australian approach which quantified an target mean and acceptable range for moisture acceptable kiln drying quality. A new standard was content. Implicit in this table is that higher quality seen as complimentary to the TIF New Zealand-Dri uses require a tighter moisture content range. scheme in that it would be less prescriptive, and • A table which, over a range of target moisture available to all New Zealand and Australian contents and end use quality levels, defines the sawmillers and lumber users. acceptable moisture content gradient. Again implicit in this table is that higher quality uses The aim is to have a document which can be require a lesser moisture content gradient. referred to by other standards (NZS 632 is still being cited as a companion document). Also a standard The proposed standard will also define maximum should help the lumber purchaser to select the acceptable levels of residual drying stress, checking, drying quality appropriate for the intended end use, colour, and distortion. and provide a quantifiable basis upon which to measure drying quality. It is still early days, but the next step is to complete the draft standard and submit it to the Standards Internationally there has been a move away from Association for consideration. For more information prescriptive standards which, as well as detailing please contact either myself or James Boyce at CHH, quality, have detailed the procedures for drying Kinleith. CHILE REVISITED Tony Haslett In 1986 on the invitation of Fundacion, Wayne regarding the cost of imported kilns (German at Miller visited Chile to provide advice on kiln NZ $300,000). Wayne thought that the development drying. More recently last year I visited two Chilean of the Chilean industry was being adversely affected corporates (Mininco and Arauco) to view radiata by lack of regular shipping services and the poor pine wood quality and their drying. It is interesting quality of domestic radiata pine. However, he was to review Wayne's impressions and compare them most impressed with the technical skills of operators with my observations. and managers and concluded: "Chile has a bright future in forestry and it is only a In Chile, prior to 1986, log exports were seen as matter of time before they develop and compete being more profitable than sawn timber so at the with New Zealand in all aspects". time of Wayne's visit investment in modem mills was only recent and there was little secondary So with hind-sight did Wayne get it right? Yes, I processing. As in NZ there had been an interest in would rate Chile as the tiger of South America. It dehumidifiers, and there was major concern has leapt ahead in sawmilling and the two corporates that I visited are now in the position to Although capital cost was seen as important, the teach NZ how to saw and reprocess radiata pine. corporates sought to fully match the processing Chilean sawrnilling is dominated by Mininco and equipment to the product market, finding the most Arauco who between them produce approximately appropriate modem technologies available 60% of Chile's annual lumber production of 3.4 internationally. Consequently Chile has some of the million m3. Figure 1 summarises Chilean most modem softwood mills in the world and in the production of forest products. next decade they are expect to commission several new 300,000 m3pa plus sawmills. Figure 1 The scale of remanufacturing is far larger than in 1994 Timber usage in Chilean forest industry (in thousands) NZ, both of these corporates having plants processing over 250,000 m3pa (expected to Commercial Logs expand). Due to low yields of full length 3 20,834.9 m clearwood they produce cut stock and finger jointed product, with edge glued panels being important (DIY stores were full of this product). Export There is an extremely high emphasis on quality, 1,842.3 m3 and again their equipment is modem, with large well-designed new factories. Chile has been highlighted as being able to consistently produce dry lumber which meets the demanding requirements of the moulding and millwork (M and M) industry of USA, and naturally I was most interested to learn how they achieved this. Initially drying and quality control It remains true that Chile has problems with its log advice was obtained and implemented from North quality. Compared to here the logs are generally Carolina, with most new kilns being European. In small (max. 45 cm dib.), have low heartwood the early 1990s the two corporates saw the potential percent, are quite swept (windy and hilly sites) and of Australasian radiata pine drying technologies and have noticeable buttressing/ fluting. They generally Windsor Engineering made their first sales. In Chile yield lumber which has an exceptionally high Windsor kilns are acknowledged as the being best incidence of compression wood (which causes warp (but most expensive), and as a reverse tribute most downstream), with smaller knots and fewer bark of their competitors now copy the Windsor kiln. encased knots than we currently expect from typical NZ logs. To date there have been only poor clearwood yields from pruning. The use of a All the new kilns were operated according to the predominant 4.1 m log length simplifies lumber NZ FRI recommended accelerated conventional handling but the sawmillers have a major hurdle in temperature (ACT) schedules. Where checking was that there are no log grades and all log sales are as a problem, a stepped ACT schedule was used. run-of-bush. There was strong interest in the use of Currently the Chilean industry almost exclusively log grades as in NZ. (except in older kilns) uses ACT schedules for drying, so why doesn't Chile have the drying Unlike in NZ sawmilling there were few accountant problems experienced in NZ? I think the short sawmill managers. Nearly all the managers and answer to this is the benefits arising from emphasis supervisors (sometimes even operators) that I met on high technical standards and quality control, as had a professional engineering qualification. I well as substantial internal reprocessing of dry believe this gives their industry a very strong lumber (which means that any drying defect can be technical background. removed without external consequences). There has been a major expansion in sawmilling and Chilean radiata has a similar kiln brown stain secondary processing, and this is expected to problem to NZ and in ripping there was similar continue over the next decade. The industry is movement of lumber off the saw. I could see dominated by super-large greenfields plants which virtually no evidence of within-ring internal utilise the most modem available technology. It is checking. incorrect to assume that Chile relies on cheap labour to be competitive- most new mills are minimising For the two corporates the standard of kilns and labour input, for example by using automatic sorters their operation was exceptionally high, with full and computers/scanners. attention to QC and feedback loops to maintain drying quality. General points for drying procedures were: . r· • Single length in kiln stack with perfect stacking (Fig. 2). • Use of ACT kiln and steaming schedules as recommended by NZFRI. • Aim me 8% for M and M and <20% for structural. • HT kilns have > 1500 kg/m2 restraint and others 600 kg/m2. • Use resistance probes for endpoint and will disregard errant measurements. • Hot meter dry loads for Fig.2: Typical Chilean kiln stacking in front of Hildebrand kilns at Mininco, Bucalemu. over 50 readings. • Defillet within 24 h and run over Wagner in- • Frequently check moisture meter against oven line with me reports to kiln drying. • Mininco test every third charge for stress prongs • M and M plants within same company also (photocopy results) and Arauco test every charge thoroughly retest drying quality on arrival. for stress as well as oven drying tests for me overall and gradients (Fig. 3). It can be seen, from their operations and products, at these two Chilean companies that their sawmilling and secondary processing was generally superior to that in NZ (especially remarkable considering their inferior resource quality). Provided the technologies are used correctly it is possible to ACT radiata for demanding M and M uses. I recommend that our industry travel to Chile to learn from their Fig.3: Drying quality control testing at Horcones, Arauco. industry. CONGRATULATIONS TO SCOTT WASTNEY Not only has Scott Wastney been busy using his the International World Chess Teams Champion deductive skills to overcome problems in the drying ships. As luck would have it the Championships are endpoint project he has also been busy in to be in Russia and Scott will be visiting Moscow competitive chess tournaments. Scott has been and Armenia. We wish Scott every success selected to represent New Zealand in September at particularly on Aeroflot. ~ ~ Environmental RAPID LEACHING TEST FOR WOOD-WASTE SOLID RESIDUES Peter Dare and John Gifford Why are leachates important? Selection of a leaching test Wastes for which re-use is not practicable are There have been many tests developed and commonly disposed of by sending them to a landfill. standardised with the aim of estimating the leaching Wastes from the sawmilling and wood processing behavoir of solid wastes. In general, leaching tests industry have traditionally been either burned are carried out for the following reasons: (which in itself generates another form of waste, ash and aerial emissions), or have been dumped. The • To identify the chemical components of the policy of most organisations today is to generate as leachate little waste as possible but inevitably some will be produced for which landfilling is the only economic • To classify wastes using set composition criteria method of disposal. (e.g., wastes may be classified as "hazardous" or "non-hazardous" according to the The best disposal option for the wastes from wood levels of specified leachate components present). processing plants may be to return them to the forest (see WPN for November 1995). Recycling the The results of leaching tests may also be used, for nutrients back to the forest helps to achieve the goal example, to ascertain the effectiveness of pre of sustainable use of our natural resources, and treatment of the waste or to obtain data for makes better sense than permanently stockpiling in mathemetical modelling of the behaviour of the a landfill. Even so, temporary stockpiles will still be waste in a landfill. needed and these are likely to be exposed to the weather. Leaching tests can be divided into two categories, extraction tests and dynamic tests. A comparison of Landfills, stockpiles, and other means of land the methods is given in the following table. The disposal intercept precipitation which leaches the extraction test involves exposing a specific quantity soluble components of the materials and, if of waste to a fixed quantity of leaching solution for a uncontrolled, will carry them into the natural water predetermined time interval. For the dynamic test, at the site. This kind of pollution is insiduous, as it the leaching solution is continuously or may take place out of sight as the leachate enters the intermittently replaced. groundwater. For this reason modem landfills are constructed with an impermeable lining and the leachate is collected and treated by some form of Comparison of leaching tests wastewater treatment system. Extraction Tests Dynamic Tests A knowledge of the leaching characteristics is • Short term . Long term necessary before any plan for the environmentally (fixed time interval) (variable time interval) acceptable disposal of a solid waste can be formulated. To assist industry in the preparation of, • Fixed liquid to solids ratio • Variable solids to liquid ratio for example, resource consent proposals, NZ FRl • Indicate potential to leach • Assess leaching trends have initiated a comprehensive study on the under simulated field production and characteristics of solid wastes, conditions including preservative treated wastes, bark, and ashes from wood waste-fuelled furnaces in New • Leachate sampled at • Leachate sampled during completion of experiment the experiment Zealand. Included in this are studies on leaching behavoir using both short (extraction) and long-term • Small sample size required • Flexible sample size (dynamic) tests. (can be large) Both of these test procedures have been leaching vessel a larger sample can be used which implemented at the NZ Forest Research Institute to overcomes problems of sample heterogeneity. By assess leaching from solid wastes produced from placing the columns in the field where they are wood processing activities. The laboratory scale exposed to natural wetting and drying, the impact of extraction test used is the Toxicity Characteristic desiccation and unsaturated flow conditions on the Leaching Procedure (TCLP) adopted by the US waste leachate quality can be considered. Column Environmental Protection Agency (EPA). The trials can also be easily modified to evaluate the dynamic test uses large (300mm diameter, 600mm effect of waste soil interactions, the effect of capping deep) plastic containers established in the field on wastes with soils and the impacts of co-disposal. A the NZ FRI campus. study is currently being established at NZ FRI using the column approach to investigate the leaching The TCLP test behavoir of ashes, bark, and wood treatment chemicals from different wood waste streams. The EPA TCLP was designed as part of a protocol intended to classify wastes on the basis of potential toxicity. A list of maximum permissible concentrations in the leachate for a range of chemicals was published as part of the protocol. The leaching procedure has been widely adapted as a stand-alone leaching test, although listed components which could be relevant to the wood processing sector include arsenic, chromium, lead, mercury, benzene, chlordane, cresols, penta-chlorophenol, 2,4,5 trichlorophenol, 2,4,6 trichloro-phenol and lindane. To carry out the test a specified quantity of material is placed in a jar of specified leaching fluid and tumbled end over end in a machine designed and built for the purpose. At the end of the specified period (normally 18 hours) the solids are filtered from the fluid, and the fluid is then analysed for the target chemicals. The choice of leaching fluid depends on the characteristics of the waste and also on what we want to achieve by the test. The TCLP standard is a weak solution of acetic acid, optionally buffered with sodium acetate, which was selected to simulate conditions in a heterogenous landfill, but for studying, for Field leaching test insulation at NZ FRI example, the ground disposal of ashes a less aggressive solution may be chosen for the leaching fluid. Results Dynamic tests The tests are in the early stages of implementation. When available the results will be published and, Leaching tests using PVC columns installed in the together with NZ FRI's expertise, will be available to field offer several major advantages over the short assist the Wood Processing industry in meeting its term extraction tests. Due to the increased size of the environmental management targets in the future. WOOD PROCESSING GROUP AREA OF EXPERTISE CONTACT Sawmill Improvement I Quality Robert Beauregard Sawmill Design I Production Planning Louw Van Wyk Log Quality I Grade Recovery Don Mcconchie Timber Grading/Timber Utilisation John Turner Timber Drying Tony Haslett Hardwood Sawing I Timber Utilization Tony Haslett Antisapstain Treatments Robin Wakeling Preservative Treatments Mick Hedley Preservation Standards Mick Hedley Environmental Technology John Gifford New Zealand Forest Research Institute Limited Phone: + 64 7 347 5899 Facsimile: + 64 7 347 9380 ... ; · : '. .\~~ :>~~~:.· :. .. ::; ;,;; ~. : -- .. _..-...... Wood Processing Division New Zealand Forest Research Institute Limited Private Bag 3020 Rotorua, New Zealand Telephone: + 64 7 347 5899 Facsimile: + 64 7 347 9380