I need some advice.
I am taking stamped metal parts (nickel silver) and heating them up to about 450 - 500 degrees. Many of them change color from a shiney silver to a bluish color. This is the effect I want.
Lately, many of the parts are not changing color. When stamped, we use a light coating of kerosene for die lube. Sometimes we run fairly dry.
IS the color change a result of the light kerosene? Is it a function of temperature? What can I do to ensure that all the parts turn bluish?
Thank You,
Wayne