Pressure Treated Plywood?
 

I have a piece of 1/2 inch ply that came off my duckboat I want to use for the fuel hatch repair. Problem is the man who sold me the duckboat said it was marine grade ply. What if its not and its pressure treated ply, it wont do right with the fiberglass and resin.....right? I dont know how to tell the difference in marine grade and pressure treated. Everybody uses the words "marine grade" when they are trying to sell a boat. :head:

PT has a greenish tint. Marine grade looks like regular plywood. Marine Grade ply is s;ightly better wood w/ better glue.

Pressure treated wood in an aluminum boat is a no-no :devil:
The chemicals used in the treating process are very corrosive to the aluminum in tin boats. I also believe you are correct in your assumption that it will not hod the resin too well.
I think you'd be better off for your hatch repair with regular plywood over the pressure treated in terms of fiberglassing the hatch. You'll be soaking it in resin anyways.

Dont use the pt plywood because it wont hold the glass, marine grade plywood has NO VOIDS IN IT and is very limited in footballs aka plugs and should not be worpped or bowed like some contruction grade plywood.

I've used " forming grade" plywood( has the red paint on the edges) with good luck for repairs. Its not cheap( all good wood is expensive), but its a lot cheaper than marine grade

you can use treated plywood ONLY if it is KENNEL DRIED AFTER THE TREATMENT