metallurgy question

[Anonymous]

Does anyone know what term would describe the coloration of many auto and bike parts where they look gold/purple etc depending on light? For example the carb connectiong rails on GS bikes, and the metal insides of some seatbelts.

For extra credit you can tell me how this effect is achieved.

Thanks much!

[Anonymous]

Your description sounds like cadmium plating. Many fasteners are plated this way as well. It is a plating process same as anodizing, chrome, nickel, etc. As far as I know, it is only for use on steel and you need to find a coating/plating business that has the process available if you want to get some pieces done.


Mark

[Robert Corrie]

And be prepaird to pay through the nose. The process is major league toxic to everything.

[bwringer]

Lots of info on various coating processes and playing with expensive evil chemicals are available here:

http://www.caswellplating.com

[Anonymous]

It's commonly called "galvanizing", although I think that refers specifically to zinc plating. Can't remember for sure. Anyway, you can easily find galvanized nails.

[Paul]

Bright zinc plate, then the parts are dipped in a water solution (or passivated) whilst still hot to produce the yellow or gold color. If they are not passivated they remain silver.
Galvanising is a different process altogether. This is when the parts are dipped into molten zinc.

[Nerobro]

Um.. Annodization doesn't belong in that list. Anno isn't plating. It's an electrochemical process that forms crystals of the base metal on the outside of the part.

With aluminum, the cruystals generated are large enough to contain dye. And by covering the metal in dye, when you annodize it, you retain the color inside the crystals.

It can also be done with titanium, but it's colors are much more limited.

The question asked.. it does sound like cadmium plating.

Plating is the deposition of a metal on another peice of material. (you can chrome plate plastic if you feel like it... it's delicate, but it "can" be done)