*sorry, the nickel solder melts at 1250F, not 800F as I previously stated.
These donuts offers reliable temperature control, and lab tests have found no off-gassing at standard temperatures. However they are no good for dabbing on directly because the ceramic is impossible to clean afterwards. Heat cannot be used to burn off residue because the solder melts at 800F. So it is going to need that bucket on, in order to keep it from ever getting dirty in the first place.