When melting the lead to make the ingots, my Dad laughed when I used a section of plywood and held it between me and the pot on the turkey fryer stand when I was feeding old lead pipes in. Never had an explosion, but when doing the rough led into ingots, that is the most dangerous time to me. I have the pot wired very tight to the fryer also so it 'taint going anywhere.
Any one here ever skim off the slag, then toss a very small piece of white candle wax into the pot to burn off even more impurities? Seen several people do it, and it does bring more stuff up.
On a side note, got some of that lead sheeting from the dentist the other day, that stuff is thin! Just have to make sure they pulled all the paper "pull tabs" off before melting.