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How to waterproof masonite

datalore

New Member
I have recently finished painting some signs by hand in an exterior latex paint, but the support is masonite, so I am worried that they will not handle the rainy season. Is there anything I can do to increase the life of these signs? I've heard that Spar Varnish might work, but I've never used it before, so I'm not sure if that's the way to go.
 
my first question would be why are we using masonite?
but whatever..you are going to have to encapsulate it, spar varnish would be one way of doing so...but again i'd really rather use a different material.
 

Marlene

New Member
primer and paint. is it real masonite? smooth on one side, bumpy on the other, really thin junk wood? no matter what you use to seal it, it will warp and look nasty. can you replace it with some outdoor grade wood?
 

Pat Whatley

New Member
Depends. I've got a couple of "temporary" signs I did on hardboard from Home Depot that have survived outdoors for three years now. The center is very slightly bowed but other than that they look good. I just primed them, coated them with enamel and vinyl lettered them. The hardboard has a smooth surface on both sides.

The cheap stuff with the smooth surface on one side and a rough texture on the other will absorb moisture like a sponge. You're going to have to completely seal it then pray a lot.
 

Perks

New Member
YUBA City...How are you doing?

Well, here is my suggestion take it or leave it...Try out this mix of 50/50 mix of boiled linseed oil and mineral spirits (turpentine can be substituted) and apply it to your material and let dry over nite and it should be ready in the morning for your latex unless you think it needs another primer before finishing.

Perks
 

petrosgraphics

New Member
if it is not tempered masonite you may have a problem... why use a varnish, why not an
exterior paint..... hope they are just temp. signs.....
 
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