I can't even remember, I was just at the dollar store and bought some NaOH (sodium hydroxide or lye) based drain cleaner to experiment with. I think it was Mr. Plumber or something like that. I'm sure it's slower given that it's probably more diluted and not warm. I also do this thing with melted candle wax to plug up holes in things like stems and seatposts where you can't easily remove the residue on the inside.