When smelting lead the clarifying agent is Beeswax.
When the lead is molten a small knob of beeswax thrown into the pot and stirred in will bring all the dross to the surface where it can be spooned off. The lead pot should then be stirred occasionally as you wait to cast your moulds.
Th size of the beeswax knob should be about the size of a hazel nut, the dross is possibly poisonous and should be discarded accordingly.
Lead acid batteries, the lead plates have arsenic in them to keep them hard so do not use lead acid battery plates.
Printers type is good for high detail casting as it has Antimony in it.
Some wheel wieghts are a composition of resin and lead so should be discarded.
Precision moulds (Bullet moulds and other metal moulds) should be at the same temperature as the lead when casting.
Crayon the insides of metal moulds with a very soft lead pencil which helps to stop sticking.
melted lead can be cast into ingots for storage by casting into the 'Frog' of a house brick. Make sure the brick is completely dry as any moisture will cause a lead explosion.
You do not want to be blinded by the splatter so eye protection is needed. casting should be done in a well ventilated place as the fumes from the beeswax and the lead can be nasty.
Clive