Vermiculite 5 gallon pail
This medium grade material is finer in "grain" size than typically found in garden supply stores. We buy this in bulk and repack it into new 5 gallon buckets.
So what do you use this for?
Normalizing forging steels. Heat your forged metal to critical temp and then bury it into the vermiculite and let it slowly cool. The insulating properties of vermiculite slow the cooling process allowing your forged metal to loose stress built up from the forging process.
You can use the bucket and vermiculite as is (careful that you don't touch hot metal to the plastic) or use a metal container for the vermiculite and use the bucket for something else.