Exterior Primers for Strong Adhesion

Finishers recommend their preferred exterior primers for use with latex paint. July 24, 2006

I am using a de-waxed shellac as a sealer for birch, maple and cedar wood (Dowel shape). I am looking for a paint (Pigmented opaque) that will strongly adhere to the shellac. This item is used in the exterior environment.

Which type of paint does everyone recommend? I would like to stay away from oil-based if possible. Someone mentioned to me that maybe I should mix my own shellac and use water base lacquer? If there are any coatings experts/chemists/specialists, I have a sample of a product that has a very strong bond that I am trying to replicate. Any input would be helpful

Forum Responses
(Finishing Forum)
From contributor L:
Shellac is not an exterior product. Using this as a base coat is asking for failure.

From contributor S:
The best suggestion for a high adhesion paint system would be to start with XIM solvent based primer. It has excellent adhesion and can be top-coated with almost any paint system. Two coats of 100% acrylic paint (premium grade) should provide excellent performance in an exterior environment.

From contributor R:
Contributor S's picks are dead on. If you don't want to spend the money on XIM primer, I would suggest a lower cost alternative is Zinsser's primer-123. As for exterior paint, make sure it is 100% Acrylic, just not acrylic or latex. There is a difference!

From contributor C:
I'd suggest using Breakthrough. It is not touted as an exterior product but the US Navy is using it on ships and I know a Garage door company that does all of their doors with it. My supplier tells me that numerous of his customers are using it on exteriors with excellent results.

My limited experiments with it (on exteriors) leads me to believe that I can expect it to outperform any other reasonably priced alternatives. The adhesion is quite excellent if you have a little tooth on your base and give it ample time to cure. Shellac is commonly used in exterior applications and will be excellent as you intend to use it. Just don't over-saturate to the point that you lose the natural tooth of the wood textures. One moderately light coat of two pound cut will be enough to stop most grain raising issues and yet leave some texture for the next coats.

Breakthrough is an excellent self primer too but it will raise the grain a bit (being water based). Polyurethane enamels would also be excellent though their slow drying character makes them difficult for most pros to use. The 2K polys would be good, though this is a higher cost option, however they do solve the slow drying problem.

From contributor A:
BIN shellac is rated as an exterior spot primer (it's on the label). I would use Muralo's exterior Ultra. It's a bombproof Acrylic. Sherwin Williams has a newer product called Duration. It's thick and can be used in extreme cold.