I'm trying to strip the seasoning (polymerized oil) off a carbon steel skillet.
Following online instructions, I've prepared a lye solution, using tap water, 2.5% concentration by weight, which ought to produce results in a matter of days; two weeks in, it's still far from being done.
It occurred to me we have hard water here, 13 dKH/15 dGH, so I'm guessing the solution just isn't as basic as it was expected to be.
Heating it up isn't an option, so I'm planning to add more crystals of sodium hydroxide to speed the reaction up.
Assuming that my diagnosis is correct, and the instructions were based on tap water hardness that is typical for the US, how much more hydroxide should I be adding to compensate for the higher hardness?