Used to use Isopropyl - but it left a white chalky residue.

I used to use vodka - but most U.S.brands have sugar in them, they look beautiful... and then it feeds the mold/mildew over time.

If you can do it....distill your own 180 proof. This is what I now do.

If you can't distill...then buy EverClear 180. Don't use 151 rum...it also has sugar.

Sincerely,
Gargoyle