The Technique of FURNITURE MAKING

Grading and classification of plywood

Clear distinction must be drawn between the grading of ply, which is concerned only with the quality of the face veneers, and the classification into groups or types, which is concerned with the nature of the bonding adhesive and the durability of the actual wood used. Hitherto plywoods were loosely grouped into interior and exterior qualities, but these terms are fairly meaningless. Admittedly,

25 Manufactured boards 1 3 ply construction 2 5 ply construction 3 Multi-ply construction 4 Blockboard 5 Laminboard 6 Battenboard (unsuitable for quality furniture-making) 7 Particle board (chipboard) 8 Grain direction when ordering

furniture-makers do not require weather - resistant plywoods, but they must be confident that the plies are well bonded and will not laminate, and that they will withstand bacterial and fungoid attack; therefore the type of bonding medium used is of importance. It is, for instance, hardly sufficient to describe a plywood as well-glued or resin-bonded, for the former term may include weak vegetable glues, while the latter may be so extended with fillers compounded of cereal flours, etc. that the implicit moisture-resistant properties are lost.

plywoods or veneered chipboards (A = cross grained; B = long grained). Medium Density Fibre Board (not shown) (MDF) resembles an inexpensive, light-coloured hardboard but sanded on both surfaces.