Earthenware pottery is made up of baked clay and calls for further care in terms of maintenance. I have cleaned mine in a gas self-cleaning oven, and have apparently been lucky, but considering the fact that I use cast iron for a majority of the time I have not had to repeat cleaning drastically in that way. In other words, if the cast iron is modern and you can easily acquire yet another identical piece, use the oven. I’ve been told the self cleaning cycle on electric ovens can go from 800 degrees F to over 1200 degrees F. 1200 degrees F doesn’t hurt cast iron but going from 1200 to 70 degrees as well promptly causes the thermal shock that does the harm. If you are lucky sufficient to inherit some cast iron this may be comparable to what you receive.