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has anyone done a 100% shellac spray finish (what cut & nozzle size)? And what is your final buff routine. Have you seen any tutorials out there.

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Mike McNerney

The biggest headache with spraying shellac is cleaning the gun afterward. Shellac seems to get in the spaces other finishes don't find and gum up the gun.
If you have a nice spraygun you might want to buy a cheap HF jamb gun for shellac that you can soak in a bucket of alcohol.
Sprayed shellac dries more slowly than French polish or lacquer and if sprayed in a dusty environment seems to acquire a fur coat.

Shellac is forgiving. It can be applied just about any way you can dream.
But lacquer, it is not.
Very different beasts.

Sure it can be done, but with all other luthierie finishing processes, practice on scrap.

The biggest woes I encountered were the flash off rates of the solvent. With a lot of air shooting the medium out of the gun, the alcohol was gone before it hit the wood.
So, dial back the air as much as possible and practice away. (It’s about as cheap finish as they come)

Come to think of it, I have to wonder… why do you want to spray it?
Once learned, french polish is pretty easy and quick.

To your specific question about gear, I use 1mm fluid tip with the gun set to 25psi when triggered. 1lb cut. 4” pattern at 4” distance.

These are the settings I use when “toning” while spraying a burst, which is pretty much just laying a full overlapping coat down but with stain in it.

Hope that helps.

Brad


Sent from my iPhone using Tapatalk Pro

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For my Walcom HVLP I use a 1.2mm tip, 27 psi, 1lb cut. Like Brad, a 4” pattern at about 4”.

Given that, I prefer to French polish.

Steve

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Steve Smith
"Music is what feelings sound like"

I'm lazy - - - Zinsser rattle can dewaxed shellac.

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Peter Havriluk

I was curious to see if anyone had anything to say about buffing shellac. I guess I have always assumed that shellac is too soft to buff.

Shellac is easy to use, the solvent fumes are benign, and the whole process is friendly to hobby building where you are learning as you go. But in my opinion, once you have the shellac perfect and the guitar has all the bugs worked out of it, it is worth it to put a thin layer of lacquer on top. Shellac wears away where the hands touch the instrument. Lacquer has a traditional gloss and is more scratch-resistant than shellac.

I buff my french polished shellac by hand with Novus 2 Fine Scratch Remover.
I wipe it on a small area at a time (maybe 6" x 6") with a Scott shop towel and buff in circles. Dry any remaining compound to a haze and wipe off with a clean dry towel.

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Craig

My setup is exactly the same as Brad's. I rarely spray shellac though, because as Dave points out, it flashes off very fast if only alcohol is used as a solvent, and that makes it a lot tougher to spray. Using lacquer thinner as the solvent instead (or adding toluene and xylene to the alcohol, same difference) gums things up.

To increase build and hardness, a number of folks I know have experimented with adding resins like sandarac, but at some quantity that gets into the range of spirit varnishes. Both Robert Ruck and Federico Sheppard liked to add a little lacquer to shellac (one of them, can't remember which) called that combination shellaquer. But there again, the material has at least some nasty toluene and xylene in it, and if you have to up your personal protection game because of that, then straight lacquer becomes more appealing.

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R.M. Mottola
LiutaioMottola.com

Author of the books Building the Steel String Acoustic Guitar and Mottola's Cyclopedic Dictionary of Lutherie Terms.

If you want a "high build" shellac finish, you can brush it on, sand it smooth after it dries , and French polish the last couple of coats. It doesn't seem to give the same results as a thin French polished finish, but it can be less work.