Neph,
This is a heavily discussed topic on the Luthiery boards I peruse. Apparently the manufactures who denature alcohol for general use use a wide variety of things, most noxious, and many toxic, to make it unpalatable. Hand rubbing shellac is a process that involves direct skin exposure to the chemical, and the fumes, for several hours at a time, over several days. Gloves are not really an option because 'feel' is critical to the process.
There are a few brands that are made specific for finishing, like Behlen Behkol, that are somewhat suitable for finish work, but it's not available in local stores (Grizzly in Bellingham - 4 hours north is the closest place to get it).
Hand rubbing guitar finishes is hard enough using the proper materials. I'm not going to make it harder by introducing intentionally added impurities, especially if those impurities are noxious and/or toxic to the person applying them. And especially not when I can get a safer and better quality alternative (even if the Government does make it a pain in the ***).
I exchanged emails with Luxco's northwest distrubutors and was told that the stuff is readily available in Montana, and can be purchased on Oregon at some stores, although not all carry it, and those that do usually keep it behind the counter. They also told me there are no laws or restrictions in the quantity purchased, or with taking back to Washington, as long as it's for personal use (i.e. I'm not re-selling or otherwise distributing it).
I'm going to be in Oregon in a few weeks anyway. I'll just pick up a case or two while I'm there. That should last me quite a long time.
I was also linked to this form, which may indicate a way to get it legally directly from the distributors.
http://liq.wa.gov/publications/IndAlcoholinfosheet.pdfI need to read it closely and see if it's something I can take advantage of.
Edit:
Also, the other forms of alcohol you mentioned can be used, but are not ideal. Some won't work at all. They do not dissolve the shellac as readily, and take longer to 'flash off', making the application much more arduous. They may also leave impurities behind in the finish. French Polish is a very sensitive process that involves building many extremely thin layers of shellac. The alcohol is used as a solvent to dissolve the shellac buttons/flakes into liquid form (1lb of shellac to a gallon of alcohol). Anything in the alcohol that doesn't evaporate ends up in the finish, and may cause problems with the shellac (haziness, crazing, not hardening, etc...). I can't imagine anything worse that spending a couple of days hand rubbing a finish onto a several thousand dollar custom made instrument, only to have it turn into a gummy mess, or crystallize and flake off.