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Absolute ethanol in the US is a chemical product and does not have denatonium in it. It isn’t much used, but you will sometimes see it in chemistry labs for IR

Absolute ethanol in the US is a chemical product and does not have denatonium in it. It isn’t much used, but you will sometimes see it in chemistry labs for IR spectroscopy. It’s at least 99%, the whole point of it is having a solvent that wipes out that huge water absorption band on IR so you can see the rest.

hilbert42 2y ago
You'll note I've put absolute alcohol in quotes, here I'm referring to industrial/commercial grade 99% EtOH that's required in processes that cannot tolerate the 5% H2O such as in the application to which I've referred. Clearly this grade should have denatonium added no matter where it's sold and I'm surprised that it's not readily available in the US. Moreover, there's no technical/chemical reason why denatonium shouldn't be added given that so little is need to be an effective bitterant. It seems to me the residual 1% 'impurities' would be much more relevant than the denatonium, even then, for most purposes, this 1% is already insignificant as far as the EtOH chemistry is concerned. On the other hand as you note absolute ethanol as used as a reagent in precision experimentation (and in the pharmaceutical industry) would have to be devoid of denatonium. I'd add these grades usually come with a certified purity analysis/impurities percentage list together with the complying standard, BP grade, etc. I'm unfamiliar with the regulations covering denaturants in the various countries but it seems to me the normal 99% grade with denatonium of the type I use is suitable for most purposes including most undergraduate lab chemistry (there's little point unnecessarily tempting students to imbibe). Incidentally, when I was studying chemistry the denatonium option wasn't yet available so labs always had absolute EtOH available and the normal commercial denatured grade was roughly EtOH ~80%, MeO ~15%, pyridine ~5%. I'm now curious as to how US-based woodworkers and painters manage using shellac if 99% denatured EtOH isn't readily available.

hilbert42 2y ago

You'll note I've put absolute alcohol in quotes, here I'm referring to industrial/commercial grade 99% EtOH that's required in processes that cannot tolerate the 5% H2O such as in the application to which I've referred. Clearly this grade should have denatonium added no matter where it's sold and I'm surprised that it's not readily available in the US. Moreover, there's no technical/chemical reason why denatonium shouldn't be added given that so little is need to be an effective bitterant. It seems to me the residual 1% 'impurities' would be much more relevant than the denatonium, even then, for most purposes, this 1% is already insignificant as far as the EtOH chemistry is concerned. On the other hand as you note absolute ethanol as used as a reagent in precision experimentation (and in the pharmaceutical industry) would have to be devoid of denatonium. I'd add these grades usually come with a certified purity analysis/impurities percentage list together with the complying standard, BP grade, etc. I'm unfamiliar with the regulations covering denaturants in the various countries but it seems to me the normal 99% grade with denatonium of the type I use is suitable for most purposes including most undergraduate lab chemistry (there's little point unnecessarily tempting students to imbibe). Incidentally, when I was studying chemistry the denatonium option wasn't yet available so labs always had absolute EtOH available and the normal commercial denatured grade was roughly EtOH ~80%, MeO ~15%, pyridine ~5%. I'm now curious as to how US-based woodworkers and painters manage using shellac if 99% denatured EtOH isn't readily available.