sqlbullet
12-17-2012, 10:28 AM
I was melting down the last of the latest haul of isotope lead on Saturday morning. In this batch I had a couple of lead rings about 12" in diameter the interlocked, about 20 lbs each. Normally I just seperate pure and alloy and make two big batches, but these were VERY hard. I knew they had been sitting for years, so I had hope that maybe they were some kind of custom shield cast way back from linotype or monotype. So, I saved them to the end and melted them seperately.
Late yesterday afternoon I tested a couple of the ingots. BHN of 10.5 average according to my Lee tester. Before I melted them, in a "knock" test a bhn 10.5 ingot would not even mar the surface. I can only guess that the rings had been quenched at some point to increase hardness. This is the first time I have encountered scrap isotope lead that was significantly harder before melting than after.
Just letting you guys know that when looking at isotope scrap, all that is really hard isn't high-antimony and high-tin.
Late yesterday afternoon I tested a couple of the ingots. BHN of 10.5 average according to my Lee tester. Before I melted them, in a "knock" test a bhn 10.5 ingot would not even mar the surface. I can only guess that the rings had been quenched at some point to increase hardness. This is the first time I have encountered scrap isotope lead that was significantly harder before melting than after.
Just letting you guys know that when looking at isotope scrap, all that is really hard isn't high-antimony and high-tin.