Topic: Why are magnesium auto and bike parts always that dark brown color?

[fastbroshi]

I was wondering this, as everything I've seen on the web says that magnesium is truly a silvery white color:



Is it just a traditional coloring to identify the metal?  I've seen a few parts painted black, but for the most part wheels, hubs, etc are always that same color.  What gives?

[MasterChief750]

may not be the best answer but i have a metal match which is essentially a hunk of magnesium and a flint. it used to be shiny when i bought it but now its all crummy and oxidised.

[754]

 Magnesium oxidized fairly quickly to a grey-black colour.
 Often painted to prevent corrosion..

[fastbroshi]

Looks like it's a coating applied to the metal to keep it from oxidizing:

http://www.ptiindustries.com/index.cfm/page/Dow-17-Magnesium-Anodize/pid/10265

[scottly]

Freshly machined mag looks like aluminum, but slightly darker. As Frank said, it quickly oxidizes to a dull grey-black, while aluminum will retain the silver color much, much longer.

[jpd748]

Its a coating to prevent the Mg from oxidising. If you take off the coating by cleaning or whatever, you need to get it recoated

[lordmoonpie]

The oxidation of magnesium happens much faster then with aluminium so race parts are often surface coated to slow the process. That is why you should be very careful buying old mag parts, especially wheels to make sure they are structurally safe. If you have mag wheels and chip the paint - stone chips or fitting tyres, you should paint over the spot immediately to prevent oxidation. I saw some old mag CR750 cases/covers on ebay a few years back and structurally they looked totally shot. Nice for the coffee table but no use on a working bike.

Some companies paint magnesium in different colours - most mag parts on a Ducati for instance will be a flat sage green colour.

[754]

 They are dark brown, becaise they are made out of the        ...ExPeNsIvE sH!t

[kayaker43]

Here's a thread from another forum discussing the color of bare magnesium. Also talks about refinishing mag wheels http://2stroker.createforumhosting.com/what-type-of-coating-t4853.html

[BLUE71TURBO]

They are dark brown, becaise they are made out of the        ...ExPeNsIvE sH!t