Since we were talking about how to heat threat an anvil, it reminded me that I also would like to hear ideas about how people heat treat hammers. I've modified a couple of hammers and had to heat treat them, but it was just random guessing on my part how to best do it. I'm talking 2 to 3 lb blacksmith hammers of different types.
The last one as a 2 lb harbor freight sledge that I turned into a rounding hammer. I simply heated the whole thing past non-magnetic and quenched it in vegetable oil. I don't believe I made any attempt to temper it after quench. Can't really remember. It doesn't seem to be as hard as it should be, It marks fairly easy if I hit anything other than hot steel.
I've heard one person once talk about running a stream of water down on the face with the idea of making the center of the face harder than the edges. I don't know how much water he was thinking, nor do I understand how you would heat treat the other end if you tried that technique.
Anyone have any experience or suggestions on how to heat treat a hammer?