The biggest difference, other than glycol having a slightly thicker viscosity, is the bath temperature that you are trying to achieve. Ethylene Glycol (anti-freeze) is highly toxic, and thus Propylene Glycol should be used, but is more expensive.
You can simply mix both glycol and ethanol in different ratios, add dry ice and the bath will the reach the minimum temperature that the mixture allows.
From Wikipedia - Mixed Solvent Cooling Baths
https://en.wikipedia.org/wiki/Cooling_bath#Mixed_Solvent_Cooling_Baths
Mixing solvents creates cooling baths with variable freezing points. Temperatures between approximately −78 °C and −17 °C can be maintained by placing coolant into a mixture of ethylene glycol and ethanol,[1] while mixtures of methanol and water span the −128 °C to 0 °C temperature range.,[2][3] Dry ice sublimes at −78 °C, while liquid nitrogen is used for colder baths.
As water or ethylene glycol freeze out of the mixture the concentration of ethanol/methanol increases. This leads to a new, lower freezing point. With dry ice these baths will never freeze solid, as pure methanol and ethanol both freeze below −78 °C (-98 °C and -114 °C, respectively).
Relative to traditional cooling baths, solvent mixtures are adaptable for a wide temperature range. In addition, the solvents necessary are cheaper and less toxic than those used in traditional baths.[1]
The flammability of alcohol was my only real concern with using it. However, considering the fact that I’m already playing with Fire by using tane, that concern is more or less mitigated via following strict safety protocols.
Alcohol makes a good bath & get a lot colder than I suspected it would. My -50C IR thermometer couldn’t read the temp. All I got from it was a ‘Lo’ reading. Good enough for me to know I can also run propane in the future, if I decide to go that route.
As far as Glycols go, I automatically go for PG due to EGs toxicity.
Can anybody discuss the handling characteristics of PG?
Alcohol dries (evaps) very quickly, ime & is relatively cheap. Cleanup after an alcohol bath is easy peasy. How does PG compare?