For instruments that I build from scratch, shellac/oil/alcohol mix til it seems "right". Varies with wood.

MOST of the older restoration work seems to be primarily shellac, some variants of amber/clear, oils, or not exactly sure...

I also see plenty of BAD and very poorly done polyurethane finishes, short of sanding and/or stripping all the way to bare wood [ I'll do that for a really nicely made one], most I'll just roughen and re coat with poly to fill scratches and refresh. If I had to guess, most of these came out of the "revival" ? Lots of heart, but not much skill or coins.....

Shellac is SO forgiving, It mixes and matches to other shellacs, blends to itself, and allows for forgiveness...

https://www.amazon.com/Industrial-Consumption-Healthcare-Veterinary-Industries/dp/B0CZBYZGC2/ref=pd_sbs_d_sccl_1_6/134-0688345-4365400

Don't know if this link will help in your quest.  

My buddy Lowell Hodel and I have built 2 mahogany body/Sitka spruce top dulcimers and used a variation on Dwain Wilder’s recipe ( https://www.bearmeadow.com/build/materials/finishes/html/shellac.html and https://www.bearmeadow.com/build/materials/finishes/html/varnish.html ) which we’re very happy with. 

2-3 light coats of 50-50 Zinsser sealcote (dewaxed shellac) and a specific denatured alcohol that has no water or unknown impurities in it (KleanStrip). 

6-9 light coats of semigloss Target Coatings emTech EM2000wvx Waterborne Alkyd Varnish. With this finish the dilution of the shellac is mandatory - at full strength the shellac beneath causes the varnish above to check; at half strength, it is a perfect sealer and causes no checking at all. 

Topped by TreWax paste wax - clear for the spruce top and mahogany colored for the body.

updated by @brudar: 06/08/26 11:25:43AM

From a web search:

Where to buy pure, 200-proof food grade ethanol in California?

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The vendor is a distillery in Maine. Probably expensive shipping for a pint of vodka.

My favorite is French polish and it is best done with pure grain alcohol. The denatured has garbage added to discourage human consumption and isn't that good for fine finishes. It can be had on Amazon...you did say best and not the cheapest.

Ethanol

I agree completely with Ken. When I build a modern dulcimer, I tend to use spray semi-gloss clear lacquer such as Deft. It's fast-drying, smooth-coating, and looks fine to me once it's knocked down with steel wool, waxed and buffed.

For historical reproductions, which I'm known for now, I try to replicate the finish that was used by the original builder.  This would include (amber) shellac, flat black milk paint, oil or whatever else I can determine that they used back then.

Great question!

When I first started making dulcimers I used violin varnish as that was what my teacher used since he was a violin maker. I think I made three or four dulcimers with this finish and started looking for something easier and less labor intensive. I tried both brush on and wipe on polyurethane finishes, but did not like the look of them. For most of the rest of time building dulcimers I used a spray on lacquer finish. Once I got in to making reproductions I started using oil and shellac finishes. I've also used milk paint. Now, to answer your question, I don't think any of the are the best finish. It just depends on what you are trying to achieve. I think for the end user a lacquer finish is the easiest to care for finish. It cleans and polishes well and looks good plus it can be satin, semi-gloss, or gloss so you can go from understated to flashy.

You can't buy denatured alcohol (labeled as such) here in Pennsylvania either, but you can buy denatured alcohol as fuel for alcohol stoves.

Ken

"The dulcimer sings a sweet song."

updated by @ken-longfield: 04/15/26 09:08:45AM

Hello everybody, just Jon Lilley here again.  With another dumb question this question is to those who are Luthier out there builders. What is your personal opinion? What do you think is the best finish for instruments? varnish, lacquer,  or French polishing. And why? 

Don't let the fact that here in California. Our wonderful politicians have decided to make French polishing indirectly illegal.  We no longer can get denatured alcohol here it's illegal

Thanks again for your opinions and feedback