As the lead melts most of the dross or dirt will come to the top and
float. When all the pieces are melted stir the lead with the ladle and
then skim off all the dirt.
To help the cleaning process a piece of paraffin can be dropped into the
pot. After it has burned, the dross is more easily skimmed off.
Another method of cleaning is to add to every ten pounds of metal, one
teaspoonful of equal parts of powdered rosin, borax and flour of
sulphur. Stir this compound in a little and when the lead is at the
proper temperature there will be a flare, flash or a little burning. A
sort of tinfoil popcorn effect will be noticed floating on top of the
metal. Continue stirring until this melts down and then skim off the
soft particles.
An easy way to test the temperature of the melted lead is to insert the
end of a pine stick for a moment. When the wood blackens or burns, the
lead is hot enough to pour.
Whenever the lead is in melted form and exposed to the air, as in the
iron pot, there will be a slight oxidation take place which appears as a
yellowish-red scum. Do not confuse this with the dross and dirt which is
to be skimmed off, but if the scum gets thick, then skim it off before
pouring any of the metal.