lead alloys do harden considerbly for a time after casting (spontanious hardneing is ment here not that from heat treatment. ).

How long does it take for lead to harden?

The lead will likely solidify within 2-3 minutes. For your safety and for better results, though, wait at least 10 minutes before trying to remove the lead from the mold.

Can you make lead harder?

Hard lead refers to a lead alloy that has one or more other metals added to make a metal that is harder than pure lead. ... This advantage can be offset by difficulty in molding the metal. The most common source of hard lead is used wheel or tire weights.