I'm building a darkroom sink. The local Lowes carries a 23/32" B/C grade exterior plywood @ 25.00 per sheet. I called a local lumber supply and they have an A/B exterior 3/4" @ 50.00 and also th B/C 3/4 in B/C @ 45.00. Does anyone know if I will be getting better plywood from the local shop , or just paying them an extra 20.00 per sheet. When I asked the locals about 23/32" plywood they said they've never heard of such a size. Thanks for any input !