there seems to be (at least in my testing) one variable in it. That's tin. Alloys like 20-1 that get there hardness just from tin don't seen to make an across the board exchange with alloys using antimony for hardness. If I have 20-1 (lead/tin) that lets call 10bhn and add it 5050 with an alloy that is say 20 bhn and youd think youd end up with a 15 bhn alloy but usually it will run around 13. Also if you don't have a lead hardness tester you cant count on your alloy being a set bhn. Ive seen what people call pure go from 6 bhn to 8 bhn and have seen wws go from 9 to 13 and what people call linotype, Ive seen anywhere from 17 to 30. But for most of us plain math is close enough. Even hardness testers can goof you up. Ive got a cabin tree and an lbt and had a Seaco. Each one of them read slightly different. So what your getting is a reading + or - about 3bhn. I use my testers more to compare alloys I have then to put a wrote in stone bhn number on an alloy.
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