Visual Classification AB/C
The quality of the surface layers of plywood is indicated by letter combinations and refers to the visual assessment of plywood.
There is a letter designation for the visible side (top) and one for the reverse (bottom). It refers to the quality of the deck veneer, the quality of the gluing, for example, is indicated differently.
In general, B/BB grade plywood offers reasonable visual quality for applications where aesthetics are not a top priority.
It combines functional properties with an acceptable surface that meets the basic requirements for many construction and wood projects.
Face quality B: clean with occasional pin knots which are the only defect allowed
Counterface quality BB: Allows sound knots smaller than 25mm and no more than 10 per square metre. Allows repaired defects up to a maximum of 8 per square metre and slight discolouration.