Is hardware store lye safe for stripping cast iron?

December 4, 2024 12:55 PM

I am trying to strip and re-season some cast iron pans. What I have acquired is this product that I bought at Home Depot, which markets itself as 100% lye. Is it safe to use for my purposes?

I am set on stripping the cast iron this way, I understand the dangers inherent to handling lye, etc. etc. What I'm trying to figure out is if this product is essentially food safe in an application where I soak pans in it, rinse the pans off, and re-season them.

Thanks!

posted by kensington314 to Grab Bag (8 answers total)

You're rinsing off the pans before seasoning, so yes. A higher grade of lye is literally used in food production (pretzels are made by dipping in a lye solution before baking, for example.) Take precautions when you use it, don't drink the lye, open a window for ventilation, and clean the pans well before seasoning and you'll be fine.
posted by blnkfrnk at 1:04 PM on December 4, 2024

This doesn't address any contamination that may be in the lye (which is unlikely), but after you rinse off the lye, you could pour on vinegar. This will neutralize any remaining lye. Probably not necessary, but it can't hurt.
posted by H21 at 1:19 PM on December 4, 2024 [1 favorite]

No issues with using a 100% lye product diluted 1:5 by weight in water for this purpose. I have often found that some built up carbon remains after the lye treatment, which can be removed using Carbon Off. Then you can remove rust with vinegar as needed and season immediately.
posted by slkinsey at 1:43 PM on December 4, 2024

I use that exact product for making soap, and I always mix the water and lye outside.

Even outside, I've noticed at times that the fumes are a bit strong in the first few minutes of mixing.

I second the idea that you need ventilation. Consider soaking the pans outside if you can.
posted by mr_bovis at 2:52 PM on December 4, 2024 [1 favorite]

I have 80 pans. I've used lye like that on 30, then I switched to electrolysis. Both work, never had issues with lye, it's just slower.
posted by Max Power at 2:57 PM on December 4, 2024 [5 favorites]

Nervous chemist chiming in - you probably know this, but when diluting, add lye to water, not the other way around.
posted by ngaiotonga at 2:38 AM on December 5, 2024 [9 favorites]

Add lye to water, not water to lye, wear gloves, wear safety goggles, have good ventilation.
posted by mhoye at 7:52 AM on December 5, 2024 [1 favorite]

If you have concerns about lye (and you should) it may surprise you that it's easy and much safer to use electrolysis to remove rust from cast iron.

I've done this several times and it works great.
posted by RonButNotStupid at 12:57 PM on December 5, 2024 [1 favorite]