I have melted cappings in my microwave in a glass cup. I use a minute or two,
depending on the amount, and watch it to be sure it is completely melted.
 
When all is melted, you will have a layer of wax at the top and honey below.
It is very easy, then, to let the wax cool and solidify for removal in one
piece (it is much easier to remove when warm than when completely cold).  Of
course, the impurities will have risen to the top of the honey layer, and will
be stuck into the underside of the solidified wax.  I brush much of this off
under running water, and the rest I remove by skimming when I melt the wax
again for molding.
 
Kate R.
Pennsylvania