New U. S. Commercial Standard for Douglas Fir Plywood

Now in effect is a new U. S. Commercial Standard, known as CS4548, for Douglas fir plywood, setting forth performance requirements for both Exterior and Interior type panels and appearance details for grades within each type.

The standard, promulgated by industry through the National Bureau of Standards, is effective as of Nov. 1.

Simultaneously, the 37 fir plywood manufacturers supporting the industry's equality control and trademarking program has adopted a new simplified A-B-C grade identification system. In addition, the new standard also sets forth even higher performance qualifications for Exterior (waterproof) plywood.

The alphabetical grade marking system provides for A, B, C and D designations for the veneers (plys) which are bonded together into panels; appearance grades within the two plywood types-Exterior and Interior-are determined by the outer plys or face veneers. The A veneer, of course, is the highest quality and compares with that veneer quality previously known as "sound.'l The "B" quality is described in paragraph two below. C and D veneers are used primarily for inner or back plys; however, defect limitations are more strict for C, the lowest grade veneer permitted in any lamination of Exterior panels.

Grade trade names will continue to be used in the identification of fir plywood. Typical is the PlyPanel' designation for the one-side material intended for interior wall paneling. However, the letter classification of veneers will call for the incorporating of the letters "A-D" as part of the distinctive PlyPanel stamp rather than the words "sound 1 side."

Other important provisions in the new standard, which replaces CS45-47 previously in effect, include:

1. fntroduction of a new appearance quality of veneer -the B quality. This presents a smooth, solid surface suitable for painting. It, however, will permit machinemade, circular plugs as repair of natural defects as well as allowing for small, tight knots.

2. Introduction of two new grades within each of the .two types by utilizing the B quality veneer. The grades are PlyBase (having one B or solid face) in the fnterior type and Exterior Utility grade, a companion grade, but with waterproof bond between plys. Then there are the A-B (sound-solid) panels in both Interior and Exterior types which will supplement the supply of two-sides ply' wood.

3. Provision' for several stock sizes of panels in most grades so there will be 2%',3',3rf', and 4 widths, and 5', 6', 7',8',9', 10', and lZ,lengths. Conversely, the total