The front door of my house has valspar polyurethane with UV protectant
over stain and every year the sun flakes it off. Is there something
better so I don't have to waste all this time dinking with it?
I should add that if you have been doing it every year part of the problem
may be insufficient surface preparation prior to adding a new coat.
Putting a finish over a failing finish with out good preparation can weaken
the new coat's ability to adhere. It will only be as good as the grip the
coat underneath it has on the wood.
Further varnish doesn't stick well to already cured varnish. Some sanding of
the whole surface has to be done to provide some tooth to the under coat so
a good mechanical bond can be made.
Just some further thoughts
Try Hydrocote Exterior. It's a water based poly. Excellent stuff.
Highland hardware carries it. I've had it on for about 2 years on some fir
exterior doors and they still look like the day it was put on. Until now,
it was my best kept secret.
Sorry, polyurethane (the chemical) is broken down by UV. It's a one
way decomposition. The manufacturer can add chemicals to the urethane
to delay the decomposition, but they won't stop it. The UV inhibitors
work by sacrificially absorbing the UV. Once all the inhibitor has
been broken down, the UV will start to work on the polymer.
Recoating works by laying down a new layer of inhibitor. You
definitely need to sand before recoating, both to give the old varnish
some scratches for physical bonding and to remove the surface oxidized
If you want a true outdoor finish, use marine spar varnish without
polyurethane. It'll yellow (heck, it starts reddish!) like crazy and
will still need recoating, but it should last longer than any PU.
So-called outdoor polyurethanes are not good. Most, if not all, water
based PU are actually emulsions of polymer in water. The solvent is
different but the polymer is essentially the same. If it's PU, it's UV
On 24 May 2004 15:25:57 -0700, firstname.lastname@example.org (topdog) wrote:
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