an old timer back in the 70's and a book he referred me too suggested fluxing lead with canning parafin. Drop a teaspoon sized chunk on to the melted lead . Be careful it can flame up.
Gently stire the pot.
Keep skimming the the dross to get all the impurities out. Cast into an ingot and test.
I usually just tested with the fingernail as he showed me,
Back in the day I would use nothing but the stick on wheeleweights as back then they were almost pure lead.
As we now know this isn't true today.
I got a scrap yard that sorts the pure soft lead from other leads.
They sell at the going market rate for the day. Last week 95 cents a pound.
Going to start stocking up.