Luger paint color

[ithacaartist]

Originally Posted by Olle

I believe they use a hot dip process, much like hot dip galvanizing (simply put: you dip it in molten metal). An automotive engineer told me that it often replaces zink on parts where the temperature varies a lot (like on exhaust systems), as the thermal expansion of aluminum is more similar to steel. The hot dip method is a bit "sloppy" and not really suited for gun parts where close tolerances are needed.

Ollie,

Yes, that figures. That would mean that one could aluminize a steel piece first, to establish an aluminum outer surface which could, in turn, be worked carefully down to a desired smoothness, and then anodized purple!

An explanation for why Al is used rather than Zn for repeatedly heated and cooled components may lie in aluminum's higher ductility than zinc. Aluminum is generally softer than zinc, more ductile/less brittle. It would tend to hang on during dimensional fluctuations of the steel below, whereas zinc would tend more to crack off.