Hi Paul,

You are right about quenching for ferrous alloys.

Copper alloys, however, are more fully anealed by quenching from a higher temperature which preserves the larger grain growth.

Probably doesn't make much difference for our purposes, but not having any control over temperature, I heat enough for the neck to glow in a dimly lit room and then quench to reduce oxidation at such a high temperatures.

Oxide colours vary with the precise alloy (mostly zinc content) and takes some practice to read. However, it does reduce oxidation by heating to a lower temperature.

Cheers,

Rob