Walking through a Menards the other day something caught my eye. They have “Plyone” 4’x5’x1/4” (actually 6mm) sheets of 7 ply underlayment. Both face sides flawless, looked into it a bit more and it’s made of void less poplar cores with birch face veneers glued with urea formaldehyde modified with melanin and or phenolic resin by its sds sheets. It makes me wonder how it would compare to marine grade plywood called for in some old plans?
