Ah ... I should have caught that sooner. So thanks you to gritch:. It seems to have been a meme, back in the day, that the last step of washing glassware was to rinse the last of the distilled water away with acetone, then "let it dry", so the moisture was gone. Funny thing is, "let it dry" doesn't mean the acetone has disappeared, its either in the room, or vented out the hood, and into the local atmosphere. So people are moving away from that. And of course, the truly lazy (like me in my undergraduate days) wanted to skip all the elbow grease washes and just soak in solvent to clean. But yeah, we're moving away from that. FWIW, if you're removing moisture, any water miscible volatile solvent (alcohols, acetonitrile) will work the same -- you've diluted the droplets of water with solvent to evaporate. Oh, and if you're using Piranha solution -- you definitely don't scrimp on the water washing, or the results are very dangerous.