When the plywood is not flat ,how to make them flat ?
How to flatten bowed or warped plywood. I once had a couple of sheets of 3/4″ x4’x10′ red cherry plywood that were badly bowed. I lightly moistened them on both sides and then lay them on the bottom of a stack of 40 sheets of 3/4 Alder Plywood .
Moisture is rarely the problem. When it is, both sides exposed to air will flatten the sheet. If they’re flat, they’ll stay flat unless temporarily unbalanced on one side by moisture.
Well,this is just one of the choices to make the plywood flat .
Another way is use mixed hardwood veneer to make plywood ,light softwood like paulownia and hardwood like eucalyptus .
But please don’t try to use pine to make 100% plywood veneer core plywood ,pine veneer core is always warpping ,I don’t know why ?