Mold! Defective Plywood??
Hopefully I put this in the right place...
I have some plywood that is mysteriously molding. Is it defective? Why would it mold?
Over a year ago I build a small box that doubles as a table for the back porch. The porch is covered and not directly exposed to the elements. The 'box' part of it is for storage. It was painted in outdoor paint. The overall paint job is good as all the non-plywood parts are not molding.
I also used used the same can of paint to paint a hand railing for the front porch that is not covered and gets the full sun as well as all the rain. It is still fine, no mold, peeling, etc. So the paint is good.
As you can see in the first attachment, the plywood is very moldy on the back side. And the other plywood panels are molding, too, but not as bad.
So I looked at the 'scrap' leftover out in my very dry storage shed. It is the only thing out there that has any mold on it. This piece has never been subjected to the elements. This is the second attachment.
I've never seen plywood mold. All I can think of is it is somehow defective.
Any ideas, thoughts, or comments?