MacGuyver4.2.0
Well-Known Member
Commercial "rubbing alcohol" isn't pure isopropanol and does leave some residue behind. 151 proof rum or using everclear would be far better.
Since you are talking letting the alcohol mixture COMPLETELY evaporate and then doing the razor scrape in the Pyrex dish, there should be very little if any residual ISO left behind. If you use 151 or Everclear, take care as they are even more flammable than 91% Isopropyl. As always, no sparks, open flames and for God's sakes...abosultely no heating. Unless you have a death wish!