George--
All of that is interesting, and it definitely shows you have lots of fascinating experience. My core question, though, was: wouldn't you agree with me that lots of fine guitars are finished with shellac, applied via the French polish method? My point in asking that question is that Rollie asked if shellac can be used to finish a guitar. The answer, of course, is yes. Lots of guitars have been finished with shellac, including great guitars by great makers. There are downsides to using it, and there are upsides, too. Just like with any finish. But I am not alone in my opinion that it is a great finish for acoustic guitars. You are describing shellac as if it is the unwanted stepchild of guitar finishes. That is your view, and your view is certainly the product of extensive experience. But it is not a universally held view. I'm asking you to agree with me on that point, in order to paint a fair picture of how the larger community of instrument makers feels, not just how you or I feel.
Regarding the comparison of the relative dangers of the solvents in nitro versus the solvent used to dissolve shellac: I'm sorry, I mean no disrespect, but you really can't compare the two. I agree that using grain alcohol is better for you than using denatured alcohol, and there are different types of denatured alcohol; some are worse for you than others. But, come on; all types of alcohol used for guitar finishing are far, far safer for the human body than the stuff that goes into nitrocellulose lacquer. Nobody wears a hazmat suit and a VOC filter mask, and works in a room with an explosion proof fan, in order to French Polish a guitar, but you would be pretty reckless to spray nitro without all of those things.
I'm sorry about your COPD. I lost both my parents to breathing disorders. It is frightening and frustrating to be unable to breath. This is one of the reasons I don't spray any finish, and why I French polish my guitars using Everclear. They sell it over the counter in liquor stores in Kentucky, by the way, in case you ever make it over that way.