How hot is too hot?

[EricC]

I've been reading here about fire damage caused by people trying to remove old seasoning by putting it in a fire.

On this forum's "Damage & Defects" page, there is the statement:

"If the fire burns too hot, however, the molecular structure of the iron can be irreparably changed."

Does anybody know what that temperature is, where it starts to affect the molecular structure?

 

[W. Hilditch]

Normal cooking in the 400 to 600° F range does not have a noticeable effect on cast iron. Seasoning does not like 600°. There seems to be changes around 1,000° making the CI more brittle which is why the self cleaning oven is chancy. Between 1,000° and 2,000° there is an increase in red color and more glass type crystals form in the iron which can cause warpage and cracking. Depending on the ore used red staining can occur around 1,500°. Cherry red about 1,800° and by 2,200 it is liquid.

Most of this is a process, not a point. The crystals will start to form about 1,000°

Hilditch

 

[EricC]

Thanks. Yes this was in reference to using a self-cleaning oven, which I've been doing with much success before finding the advice, and warnings, on this forum.

My oven self-cleans at 800°, according to the manufacturer, so those temps line up with why I haven't had any problems with heat damage (I realize other ovens clean at higher temps so YMMV).

Heat warping is another risk, I guess, but I've lucked out so far.