I’m having problems spraying this material. It’s very fast drying. I did thin the material with alcohol. That has helped. But the surface doesn’t seem to level.. And I get light spots on the surface .
I’m running a hvlp cup gun at 30 psi.
The tip is 1.7 mm. It seems the best.
I have other guns with a 1 mm 1.4 mm
but couldn’t seem to get enough material to come out of the gun.
I’m confused.

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I suggest ask on a luthiers forum. Spirit varnish in not used in professional woodworking shops.

I thought this was traditionally padded onto the instrument in a long laborious process. Sounds like you are trying to do a shortcut.

By the look and color of the sprayed surface, unless you have added color to it, my educated guess is your using orange shellac...am I correct.??
If so then as Leo mentioned, this is almost always applied by friction polishing of the surfaces, more commonly known as French polishing, though it was not really invented by the French.! There have been times when others elsewhere have brushed it on, but brushing does not produce a deep looking high gloss mirror finish, that friction polishing does.!I would strongly advise you to use the next best thing which in this case would be Nitro cellulose lacquer, which can be sprayed sanded and polished to a very similar glossy finish in a very quick amount of time, as compared to the French polishing method.! If you do so, any help you need on using it can be found online or in books or here if absolutely necessary.!

I started looking into Spirit Varnish and it's a complicated formula using alcohol and quite a few dry chemicals. In the youtube vids I looked at 2 of them applied it with a brush and the other used a air brush to apply it. I didn't see anyone padding it on which is a French Polish. The guy that had sprayed it on got a satin finish by rubbing it with pumice stone.

Yes, spirit Varnishes can be a number of alcohol soluble natural resins, along with partially alcohol soluble or compatible gums. All which give or offer particular attributes to the final coating. Sandrac, the clearest and hardest of the natural resins, started the concept and art of applying a clear water colored coating onto the furnishings of Louis XIIII. Palace in Versailles. In time, mastic gum was added to the Sandrac to give it flexability, which Sandrac by itself had hardly any. What the final polish contained no one knows, Though many recipes were printed later on and which I duplicater, were in themselves inferior to the original.! There were brushing Varnishes for sure, before the French polishing method, but again none were capable of giving the same results as the friction polishing method which was alone capable of giving a thin deep high gloss to those things it was applied to.
I have a proprietary coating based on shellac's and a blend of solvents that can reproduce everything but the water whiteness of the original Sandrac coating, I developed it because normal shellac, that has been solved and reduced with Anhydrous Ethel alcohol, has the unfortunate problem of "esterification" Meaning it becomes somewhat gummy, looses its initial hardness.
My solvent blend, which are still alcohols prevent this, the shellac blend also allows it's use in high humidity climates like Florida, from blushing white.
In all, it is the best long life spray able product I know of but it is not available to the public....sorry
Maybe when I die I will have my son make and sell it, but for now, not happening.!