Plywood QC Inspection Checklist : Part 39 Core quality
The poplar core veneer is made & sold by thousands of veneer mills scattered through the poplar growing region – the plywood mills do not peel this veneer themselves. This veneer is bought by the plywood mills as grade #1, #2 & #3. Simply put, the #1 highest) grade has larger pieces with fewer defects and #3 (lowest) grade has smaller pieces with greater defect. The obvious esult of using lower grade core veneer is a greater number of core voids. The second (and less obvious) result is that the smaller pieces of veneer will not go through the rolling dryer. I have seen many mills sorting the veneer by size and mixing veneer in their core lay-up process: large pieces dried in the dryer with smaller pieces that are just air dried. This will result in a panel with ide variation in moisture content – the worst possible scenario.