I've dissolved de-waxed shellac flakes in methyl hydrate (which contains methyl alcohol), and I would like to know if the alcohol retains some of its toxicity after it has dried. Intuitively it's so volatile that I don't think anything remains, but I'm not sure.
Note on methyl hydrate vs denatured alcohol: Before I purchased this product, I thought methyl hydrate was the same thing as "denatured alcohol" (aka "methylated spirits"). Although the two types of solvent are interchangeable in function when it comes to dissolving shellac, it seems they are very different chemically -- with methyl hydrate being apparently methanol, and denatured alcohol (aka methylated spirits) being ethanol mixed with another type.
In the particular case of the product I used, "Methyl Hydrate", there are no ingredients listed on the back label. The front mentions "99.9%" pure. Pure of what? Just methanol, or pure mix of 99.9% ethanol with methanol? The fluid from this bottle is transparent. I've seen purple ones too in videos, but maybe they were denatured alcohol.
I've sent an email to their support. But received no reply yet, after a week.
95% grain (drinking) alcohol from the liquor cabinet. Nothing more concentrated than 95% is sold in my area. It might not be concentrated enough, and might contain sugars. Bad idea?
99% isopropyl (rubbing) alcohol from the medicine cabinet? Bad idea?
Edit: Feedback from the local poison center
Before posting this question, I'd initially wiped a surface with a methyl-hydrated rag in preparation of applying shellac. And I stopped in my tracks, realising it was perhaps the wrong solvent to use.
I placed a (very quick) call to my local poison center, (Vancouver BC, Canada), to determine what to do after spilling methyl hydrate on food contact surfaces (like a kitchen counter, dining table, or wooden cutting board). They made several (somewhat controversial) recommendations:
methanol is highly toxic. should wear adequate protection. sure.
methanol "does not just evaporate". This claim is dubious, but I figured they assumed it had been mixed with water, or booze. Methanol is water soluble, after all. When I mentioned that it was precisely the point of pure methanol as a solvent, i.e. to evaporate quickly, they seemed perplexed. And it made me very suspicious about the veracity of the other claims.
in the case of the wooden cutting board. they mentioned it would be preferable to just discard it, or clean it thoroughly with dish soap. For a plastic cutting board, they suggested a run through the dishwasher. For a melamine counter top, they suggested cleaning it thoroughly with water and soap. I would have expected them to suggest letting it dry, followed by cleaning, but that would have been a surprising answer, given (2). At least there was some consistency.