Finishing Problem

General finishes has one called exterior 450 , i have used it out side, been out there for about 2 years or so, looks like new. might want to consider it , just my .02

It is not that the spar varnish will yellow the white paint. The Spar varnish itself has a yellow tint. Therefore you cannot seal the white paint to prevent it from yellowing when you apply the finish. The varnish itself will continue to yellow. I believe shellac and lacquer (from personal experience) have the same problem. It is my understanding that the lack of yellowing is one of the major advantages of water based finishes. You should probably wait for a few more comments though, as I have never used a water based finish.

-- Jack T, John 3:16 "For God so loved the world that he gave his only Son, so that everyone who believes in him might not perish but might have eternal life."

Are you saying that you will be using an latex paint then spar varnish on top?’
Or oil based paint?

Spar Varnish comes out of the can amber color, some brands are even darker. So no matter what spar varnish you use it will yellow the paint. The reason why spar varnish is amber or will yellow more because it contains a high percentage of oil. It can be tung oil and linseed oil cooked in phenolic resin.

There is no need to use spar varnish on top exterior paint. A good quality paint will be enough for your particular product.

The current paint market best durability paint is Benjamin Moore Aura. Which cost $50-60 a gallon.

-- shdesign3.com

My wife is using oil based paint. We are not painting the whole plate just the logo. I know that all, or most, oil based varnishes have an amber tint. Hens, my question. Is there a way to lock in the color? I am very willing to use a clear water based top coat, however, I worry about durability. Here in Vegas I’m not so worried about water because we rarely get any rain. But these plates will be on the front of a car. They will get sandblasted with dust, dirt and anything else that kicks up. If the GF 450 doesn’t yellow then that will be the way to go. I just will have to order it on line because I can’t buy GF products here.

-- "Courage is being scared to death -- but saddling up anyway."

Oil based is a poor choice for hot weather.

In Las Vegas, where you have 85-90 degree temperature water base poly products will not last. Maybe here in California. Actually nothing last outdoors.

Look there is no need to top coat latex with any finish.
Just use a high quality paint and you’ll be good.

-- shdesign3.com

The only reason I want to top coat these plates is because only the the classic car logo will be painted. The rest of the plate will be bare wood.

-- "Courage is being scared to death -- but saddling up anyway."

Then your only option is water based poly like charlie refer to.

To solve your yellowing problem use latex to paint the logo.

-- shdesign3.com

How about finishing the bare wood first, then painting after? Since you’re using an oil-based paint you shouldn’t have any adhesion problems.

That way you can take advantage of the “warming” effect spar varnish can have on bare wood… whereas waterbased poly’s largely lose that bonus.

I don’t recommend doing that.

If you paint oil based paint on top of spar varnish it will crack.
Spar varnish contains a higher percentage of oil for flexing.
Oil based paint itself is like a hard film like polyurethane.

Unless you tape off the logo part.

-- shdesign3.com

what about automotive clear laquer?

Steve

-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

All professional basketball courts are finished with water based poly. It is tough enough for any application.

-- Sam Hamory - The project is never finished until its "finished"!

For exterior pupose, its not durability, its how long will it last in 90 degree sun.

-- shdesign3.com

Not sure if I understand your problem, but I can give a couple outdoor sign methods.

Method #1 is if you plan to seal the wood;
a) Finish the wood first with the sealer you want and let it completely dry.
b) Then carve, route or cut the logo and wording you want. That will expose raw wood that you can then flood with a good exterior paint in color you want.
c) Depending on how graceful you are, you can take a ROS or sanding pad with fine grit to take any excess paint off.
d) You could wax it then.

Method #2 is if you are leaving the wood natural;
a) Spray or brush shellac on the wood and let it dry
b) Then carve, route or cut the logo and wording you want. That will expose raw wood that you can then flood with a good exterior paint in color you want.
c) Run it thought a planer, v-drum or belt sander to remove the top 1/32nd

Steve.

You can paint first with acrylic paint and seal over it with epoxy resin. The resin is thinned out with iso propyl alcohol to any viscosity you want. You can thin it and spray with an HVLP gun. Surfboard epoxy is made to stay clear and not yellow, Aerialite is one brand name. This process is done all the time on surfboards with the substrate painted and epoxy laminated over. Very durable finish and will withstand weather especially heat.

How much time do these classic cars actually sit outdoors? I would think that would be limited so the sum might not be that bog as factor.