The way I understand it a properly fired earthenware pot (which is only fired to about 500*c) when done over an open fire) will go fine over an open flame for cooking, boiling, etc. This is not like ceramic coffee cups in the cubbord at home (fired at around 1000*c) which would in fact crack when in contact with any uneven heat like cooking or boiling over an open flame. This is based on what I read at BCUK... I have not test it yet. We'll know for sure soon enough. Hopefully I will find the time to try this experiment this Sunday but if I dont, I have a camping trip planned for May 30th through June 3rd and will certainly have the time to try this then.