The reason methanol is the preferred solvent for boric acid is it
holds twice as much boric acid as ethanol and three times as much as
isopropyl. While you can buy 99% isopropyl it is not common and
quite expensive. Mostly what you will find is the medical grade
which is 70% alcohol and 30% water. Doesn’t burn off very well at
all. As for the dangers of breathing the alcohol fumes THEY ARE ALL
TOXIC. You should not be using them in situations where you don’t
have good ventilation. Do not fool yourself into thinking that
because you are using isopropyl that you are somehow safer.
Boric acid solubility by weight percentage in three alcohols.
Ethanol 11.96% (Denatured alcohol is typically over 95% ethanol)
1-Propanol (isopropyl alcohol) 7.34 %
James Binnion Metal Arts