[Derek1]

I am a mandolin builder that is interested in using alcohol soluble polymide resin for finishing wood. Is there someone here with working knowledge of polymide resin that can help me determine if this is a viable option?

Thank you,
Derek Smith
Northfield Mandolins

[Corribus]

I don't have much experience in this area, but it may be helpful to know what you mean by "a viable option". An option for what property?

I imagine that wood varnishes for violins and related instruments have been worked out for centuries. Is there a reason you can't use a conventional finishing agent? What are you hoping to improve upon?

[Derek1]

Thanks for your reply Corribus.

I am currently using a centuries old recipe consisting of natural shellac flake dissolved in ethanol. It is arguably unsurpassed in beauty and tone as far as instrument makers are concerned. The two main cons are it's relatively low resistance to moisture and heat, it's continual resolubility in alcohol.

Many traditonal builders opt for oil-based finishes which, once cured, are not resoluble and much more resistant to water. I, and others, don't like these for the more toxic solvents involved, the difficulty in repair, and the long cure times.

Lacquers are the modern standard in finishing but they involve very harmful solvents and don't look as nice in my opinion. Adhesion issues between the different materials can be a problem sometimes as well. In part due to the different solvents

I'm searching for a simple resin that I could dissolve in ethanol and apply as a topcoat over my shellac. Much of what I read about polymides sound excellent for this. Water resistant, good adhesion, good solvent release, optical clarity. But I find nothing of someone else doing what I propose so I'm a little dubious.

Ultimately it needs to be able to be a reliable coating for many years. I would need to perform extensive testing but perhaps someone who is familiar with polymide properties could save me the effort if there is a good reason to not pursue this.

Thank you so much for your time...