Hi all, First post here. I finish musical instruments and finish many in a traditional spirit varnish. I build with spray coats and complete with french polish. Many of these instruments are used in hot and humid situations and develop white blooming clouds in the finish. I can successfully defend against this with lacquer or oil varnish but am looking for an alcohol based alternative that will topcoat the spirit varnish and have better water resistance. I mix my own varnish with pure ethanol and like the low toxicity of this. I have found acrylic and polyamide resins that are alcohol soluble but am not sure if they will suffice as a coating on there own. Anyone ever try these as a coating? Why is there no other alcohol based finishes other than shellac?

You can dilute epoxy resin(West System) with denatured alcohol.

People used to think that diluting as a first coat will increase the moisture resistance. West System tested it. Diluting actually lowers the moisture resistance and physical properties. Epoxy is not varnish. I don't think that diluting varnish accomplishes anything either.

Even if you dilute epoxy it will have the properties you describe. I don't know how it looks when you dilute it with alcohol then brush it.

isopropyl alcohol(rubbing) is the best solvent for epoxies. Much better than acetone or denatured. I use it all the time for cleanup. You can get 91% at CVS.

Thanks for the response Adam. I'd like to stay away from epoxy. I should add that my goal is to have a alcohol soluble, repairable, water resistant finish. I have everything but water resistant from my current spirit varnish. I think the blooming issue comes from microscopic holes in the cured finish due to water evaporating out of the alcohol. Maybe several topics here.

Go to http://www.woodfinishingenterprises.com

It might help....

Thanks Pete. I have and do still experiment with adding various natural resins as found at the link you provided. We are beginning higher production though and would love to have a simpler and more consistent, large scale solution. I am still amazed at little there is available for a modern alcohol soluble finish. I did find that Hesse-Lignal out of Germany makes an ethanol based lacquer they say is low VOC for coating children's toys. I'm investigating this as a possibility and hope it can be redissilved with alcohol for repair.

Derek, Is there a reason you want alcohol as your solvent? What if your coating system could be repaired or redissolved with a different solvent?
If interested I may be able to put you in touch with a guy that can formulate a coating for you or may already make one.

Thanks Bob, I'm definitely interested in learning more about other options. I really like the low toxicity of grain alcohol. And I think if I could topcoat my spirit varnish with an alcohol based acrylic resin then I should get great adhesion while hopefully some better moisture barrier and maybe even more general durability. The final hope is to be able to redissolve the topcoat layer in alcohol for touchup work. I know the alcohol soluble acrylic resins exist but have yet to find if what I want is possible. All that said, I'm not opposed to investigating another option that uses mineral spirits or maybe turpentine which I'm not really familiar with. These may even have an advantage in that removing or working with the topcoat would not chemically affect the spirit varnish.

What is wrong with shellac? Alcohol based products dry very fast. That may present a problem for your plan.

I would say Durability is a major weak point

I love shellac and still want to use it for the build coats. I'm looking to add a barrier topcoat via spray gun that will have better moisture barrier. I have had success with nitro lacquer but I'd love to find a less toxic alternative. So far it's the best because it bonds well to the shellac and is fairly easy to repair. Tru-oil is an awesome moisture barrier when decently thick. I can't yet get it to spray without little bubbles though. Lays out great! Hand application requires many applications. I'm still fiddling with this.