Returning home after using cast iron cookware on a camping trip, I forgot to clean the cast iron in the midst of much unpacking and other matters. As a result of A) leaving any cookware with food in it for almost a week, and B) leaving a cast iron pot sealed with its cover on it, there was more mold in that cast iron pot than I'd ever seen on any cookware before.

My main priority was to clean all the mold ASAP. I put the pot and pan (lid) outside in my yard, poured bleach on it, then followed up with boiling water. That seemed to kill all the mold, and nearby grass. After that, and rainy weather the following day when I intended to leave it outside to air out and dry in the sun, the cast iron became very rusted.

Now I embark on the task of scraping off all the rust using steel wool, scrubbing the cookware with soap, rinsing it in hot water, drying it, then reseasoning it. This all has me wondering: when cast iron cookware gets very moldy, what's the most efficient and accessible way to make it hygienic and usable again?

3 Answers 3


The most efficient method would be to skip the whole bleach step, and start right in on burning the mold (and seasoning) off either in a fire or in an oven on the self-clean cycle. Then proceed to re-seasoning.

Taking the bleach side trip adds the joy of rust removal, which you can avoid if you don't let the cleaned (by fire/heat) cast iron get damp before oiling it and starting the re-seasoning process.

  • Ya the rust removal isn't easy!
    – cr0
    Commented Jul 29, 2017 at 2:21
  • 2
    If you felt the need to kill the mold (and your grass) with bleach (which is not needed, as enough fire to clean off the molding seasoning will kill the mold, but I can understand the gut reaction) you could have skipped (or at least reduced) the rusting phase by putting the damp, rinsed, cast iron in at least a 250°F oven to dry it. But I'd still burn off that seasoning and re-season anyway (my gut reaction) and as such I'd just get right to that.
    – Ecnerwal
    Commented Jul 29, 2017 at 2:26

You have done it. Remove rust with fine steel wool (XXXX) and then wash with a mild dish soap, then re-season. Dry thoroughly.


Killing the mold with hydrogen perioxide works better than bleach. Wash thoroughly with the peroxide and then put in the oven to reseason. Let it sit for a week...if the mold persists, repeat the process.

  • Isn't bleach another name for hydrogen peroxide?
    – Mirror318
    Commented Oct 11, 2019 at 20:33
  • 1
    While hydrogen peroxide is a bleaching agent, what is sold as household bleach is typically sodium hypochlorite. Commented Oct 12, 2019 at 3:10

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