IMPORTANT NOTE

This web page is part of a web site that is no longer actively maintained by anybody at ANU SRES. It has been left on the web due to its apparent popularity (every time we've removed it, people have complained within 24 hours), but is presented AS IS - attempting to contact any individual named on the page is likely to fail, and the SRES webmaster doesn't want to hear about such failures or entertain any communication about updating of the page's contents. You have been warned.

Raw Material Utilised in Veneer and Plywood Production

Raw Material Utilised in Veneer and Plywood Production

Topics


(Courtesy of Dr. P.D.Evans)

General:-Raw material

Veneer and plywood products are produced from both hardwood and softwood tree species. Species utilised include Acacia melonoxylon (Blackwood), Agathis microstachya (Kauri pine), Atherosperma moschatum (Blackheart sassafras), Argyrodendron actinophyllum (Brown tulip oak), Ceratopetalum apetalum (Coachwood), Cryptocarya glaucescens (Silver sycamore), Doryphora sassafras (Golden sassafras), Eucalyptus alba (White gum), E. andrewsii (New England Blackbutt), E. delegatensis (Alpine ash), E. grandis (Flooded gum), E. maculata (Spotted gum), E. obliqua (Messmate), E. pilularis (Blackbutt), E. regnans (Mountain ash), E. resinifera (Red mahogany), E. saligna (Blue gum), all Stringybarks, Endiandra palmerstonii (Queensland Walnut), Eucryphia lucida (Leatherwood), Grevillea robusta (Silky oak), Nothofagus cunninghamii (Mrytle), Phyllocladus aspeniifolius (Celery top pine), Radiata pine (clear and knotty), Schizomeria ovata (White birch), Sloanea woollsii (Yellow carabeen), Syncarpia glomulifera (Turpentine),

Historically, veneer and plywood production has required the use of high quality, high cost raw materials. The raw material requirements for plywood manufacture varies considerably.

Baldwin (1981), uses two sets of criteria in assessing the value of a particular timber species.

  1. Timber in log form - In general criteria relates to log size, quality and grades, log transport and handling requirements, and log protection and quarantine.

    • Rotary cut or peeled veneer - logs above average diameter, cylindrical in shape and have minimum defects are sought after. However due to development in manufacturing techniques and equipment small diameter logs can now be economically utilised.

    • For sliced veneers - log requirements are more specific and greater emphasis is placed on value of the end product. Elected pieces of burls, stumps and distorted logs, that provide highly figured and coloured wood suitable for decorative purposes. These materials are relatively high cost raw materials. Generally raw material requirements are less stringent for the manufacture of multi-ply plywood as larger quantities of core veneers are required than for 3-ply plywood.

  • Physical characteristics of wood which determines the technical suitability of a particular species for veneer or plywood manufacture.

    Baldwin (1981) indicates that the quality of logs that are acceptable will vary according to the cost of the logs at the plywood mill. If this is high from a combination of stumpage, felling, and transport charges, then only selected qualities can usually be accepted. As the percentage recovery of plywood from the log becomes very important. This is particularly true for logs imported from overseas, because ocean freight may add from 50 to 100 percent to the cost. If logs are inexpensive then quality requirements may be lowered because losses caused by rounding and veneer clipping may be compensated by the log price. However it must be taken into account that the use of lower qualities involves extra labour, often with some lowering of grade of the finished product.

    Other Factors

    Other factors to be considered when determining the value of a species for plywood are behaviour in transport and storage. Some logs develop radial or dimensional split (especially utilisation of secondary growth hardwood) upon drying (see Pic 1) and most wood species are susceptible to insect attack, staining or decay.

    Picture 1:- End splitting (Courtesy of Dr. P.D.Evans)

    Back Home
    Top of page