Karl, the technique is straightforward but tricky. First the part must be absolutely squeeky clean. The heat source must be oxygen poor, fuel rich. A charcoal fire with very low air draft or a gas burner with low air and a "smoky" burn or an acetylene torch, same conditions. Heat the piece slowly and keep it at the blue temperature for at least 10 minutes, without overheating (therin lies the tricky part). Low oxy levels cause the blue to form slowly and bind better to the surface. Immeadiately quench in oil when removing from the heat. I suggest highly polished ten penny nails as a learning tool. You do the polishing so you learn two things.
Heinz
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