Work the dish with soda ash and your torch to clean it. Sometimes you will find small steel springs and other metal items in the slag. Pour the molten slag off as you work the dish clean.
I would not use the 'cleaned' dish for melting refined metals for obvious reasons, but it will still suffice for inquarting operations until it is finally cracked and destroyed from the repeated heating. The brown clay dishes have a limited life of three to five cycles of use, depending on how well you baby them by slowly heating them up to remove the water before applying full heat. Once a dish cracks all the way across it's surface it is no longer safe to use with out risking total failure under full heat and possible metal spills.
These dishes are also brittle and subject to mechanical shock so avoid dropping them and store them in a safe area where they will not be subject to other mechanical stresses.
Lastly, avoid heating the dish to red heat and rapidly cooling it to get the most life out of each dish. Using the dish in the insulating bottom of the mini-firebrick oven helps heat and cool the dish evenly during and after use.
Steve
