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

https://youtu.be/xGnr8ATHHX8

beautiful okoume logs