i had come across some ply that i had not seen before
the stuff i had was formerly a display
it is very stiff and is 7 ply
well i just happened to come across it it is sold as underlayment and has nailing guides on it or maybe they are tiling guides on one side
it looks like the marks are just ink sprayed on and look like they could be sanded off
the sheets i saw were four by five
similar but different this is a video of marine ply manufacture i did not know it was so hands on but maybe that video is old
formatting link
beautiful okoume logs