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PS ,Plywood may be classified upon direction of grains in the plies and on the type of adhesive
used. Normally the alternate plies are oriented at 30° or 60° in star plywood. The faces are
arranged with the grain at 45° to that of the centres in diagonal plywood. When the plies are
bonded together with water-soluble glues such as casein glue, interior grade plywood is obtained
and when bonded with phenol formaldehyde adhesive it is identified as exterior grade plywood
which is completely water proof.
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f 22q X Plywood for general purposes should be of the following two grades,
depending upon the bond strength developed by the adhesive used for bonding the veneers:
(a) Boiling water resistant or BWR Grade, and
(b) Moisture resistant or MR Grade.f 22e!!X2Plywood for general purposes should be classified into three types,
namely, AA, AB and BB based on the quality of the two surfaces, namely, A and B in terms of
general permissible defects. The type of plywood should, therefore, be designated by the kind
of surfaces of the panels. The better quality surface should be called 'face', and the opposite side
should be called 'back'. If the face and the back are of the same quality, they are not distinguished.
The type of plywood would denote first the quality of face followed by the quality of back. For
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