I have several buckets of COWWs.
Many years ago I had WWs and for convenience smelted into 1# ingots and marked them with a magic marker. As time went on, the lead oxidized and the marker faded to the point that I couldn't differentiate the WW ingots from the other ingots so I ended up simply putting all my unknown lead into the pot and casting boolits til it was all gone.
Bcuz of my experience in the past I have hesitated to melt my WWs.
How do you guys mark your 'specialty' ingots in order to be able to ID them several years down the road ?
I've toyed with the idea of making a fairly large stamp of the letter W and heat it with a torch to 'brand' those ingots.
I don't have (haven't built it yet) a hardness tester.