Does Varnish "breathe"

John Hart · Post by **John Hart** » Tue Mar 20, 2007 11:54 am

We have often read that slopping on epoxy on the interior and underside of a wooden boat encapsulizes the wood and thereby prevents the evaporation of any moisture that eventually finds it's way into that wood... even if it doesn't prevent it entirely, at least is retards the evaporation of moisture and sets up favorable conditons for rot to occur.

Now that I think back on when I refinished the interior of my Seacoaster, I flooded CPES on the below waterline areas, and then 5 coats of varnish throughout... (something like 75% Min spirits/Penetrol 25% varnish... then 50/50, 75% varnish, then 100% thereafter)

I sort of laid it on pretty thick, and tried to make sure it flowed into and sealed everywhere I could... Now, any water that I do see whenever I remove the floorboards, rolls around like water on poly, and is easily toweled up. (At most, just an ounce or two)

I always assumed that since the interior laps were varnished at the factory, this finish did not suffer the undersireable consequences presented by an epoxy coating.... I don't remember whether the laps were varnished before or after assembly.

Is this a correct perspective? It is a little late for me now, but I'd like to know for the next boat.....

a j r · Post by **a j r** » Tue Mar 20, 2007 2:11 pm

All the finishes were put on after assembly at the factory. That's why there is no sealer or varnish on the back sides of ribs, etc... they didn't even get finish on the undersides of seats.

CPES is a sealer and not a hard epoxy. It is very liquid as you may recall and penetrates into the cellular structure of the wood. It does allowing "breathing" as does varnish.

Andreas

John Hart · Post by **John Hart** » Wed Mar 21, 2007 1:03 pm

Thanks Andreas... I was hoping you would say that about the varnish. I did know that CPES wicked in, to the point that wood was still able to breathe... It is an incredible product.... I have let a little pool of it dry on a sheet of poly for a few days, and although it is hard to a fingenail poke, is is still flexible. That makes me comfortable that even though it wicks into and partically staturates old wood, it still provides vapor transfer and does not make the wood brittle...

Thanks again.