Before we start on the process of forming sinkers, a couple of warnings won't hurt. In the main these come from the wives and assistants of practising sinker makers. The melting point of lead is around 330 degrees Celsius. A rough translation of that is bloody hot so a rag or gloves should be kept close to the working area. Assistants also need to be warned that moulds look the same whether hot or cold.
Lead sometimes has impurities alloyed with it or coating it.
These may be more toxic than the lead itself which is dangerous enough. However the real problem in your kitchen is nasty fumes especially as you melt battery lead. Unless the working area is well ventilated it may be wise to avoid batteries altogether. Saucepans and ladles at this temperature will not damage stove enamel or metal surfaces but all other types of table or bench tops should be avoided or covered with thick rags. Procedure Wipe petroleum jelly over the straight length of wire and lay it in the groove that passes through the centre of the mould.