More testing 
Discussion
We ran these tests at a bush bush bash with great results.
Stainless steel?
Yes, it was actually an excuse to make an asado, come over.
Those temps are not representative for house fires
I didn’t have a thermometer, but it was amongst red coals for almos 3 hours. Probably reaching 500C.
I’ve seen and been in house fires. I can tell you that if you HODL like this, you would be fine.
Having said this, feel free to put your seed phrase, written in paper, in a bank vault if you trust them more.
Assuming you are using stainless steel (316) you should be fine. Just wanted to highlight that depending the location house fires average between 600-800C (1100-1500F) but can have peaks up to 1100C (2000F).
Keeping your generational wealth on paper is just plain stupid