Re: Anybody use Roseburg "Marine Plywood"? (fir-ply checking - MDO a
- I have had good luck using penitrol on fir plywood by following their instructions. Mainly putting wet on wet for as long as it takes to keep the surface shiny, usually 20 or thirty minutes and multiple coats. This works well but I would not use it under epoxy as it takes weeks to fully cure but can be painted over in a day. I think the problem is that people are using too viscus of an epoxy resin that cures too fast. The microscopic voids in the outer layer are down at the glue line not on the surface and most general purpose epoxys are too thick to penetrate. Using a slow 24 hour cure epoxy and going over and over until the surface stays shiny would minimise the checking.
A word of caution epoxys cannot be thinned in the conventional way as all you get is a thinner coat. The problem is the very large molecule of a viscus epoxy is what limits penetration so you need one with a small molecule. I think the original west system resin with the slowest hardener would work. all bets are off if you are using really crappy plywood!
The mill in Shelton does/can make ¼ inch 2S Crezon MDO . The problem is getting less than a unit. I tried to put together a group buy a couple of years ago but only got about ¼ of the sheets spoken for and so never placed the order.