Summary for bright anodized aluminum Discussion
Bright anodized aluminum is the likely finish for the Jeep rocker trim moldings in question. Eric Bickel asked whether the 1970s-1980s CJ rocker moldings that looked chrome-like were chrome plated, anodized, or polished aluminum, noting that the black anodized versions faded while the bright versions did not. Ted Mooney replied that, although visual identification is usually unreliable, this is one case where the finish can be judged: the rocker trim moldings are bright anodized aluminum. He explained that chrome plating is typically brighter, bluer, and less diffuse, while even well-polished aluminum looks pasty white when compared side by side with chrome. His practical advice was to compare the part against known chrome plating if possible, since direct comparison makes the difference easier to see.
January 14, 2018
Q. I am trying determine how Jeep finished the aluminum rocker trim moldings on CJs in the 1970-1980s. We know they made two types of rockers: black anodized and a “bright” version that looks like chrome. The black anodized moldings faded quickly to just an aluminum color. The “bright” version did not fade.
I am attaching two pictures. One compares the front of two “bright” moldings (on the left) to the front of two black moldings. The second picture shows the backside of these same rockers. In this case you can see the black clearly.
What I am trying to figure out is how the “bright” ones (the two on the left) were finished. Are they chrome plated? Are they anodized? Are they polished aluminum? How can I tell?
Thank you!
Eric
Eric Bickel
– Austin, Texas, USA
Ed. note: This RFQ is outdated, but technical replies are welcome, and readers are encouraged to post their own RFQs. But no public commercial suggestions please ( huh? why?).
A. Hi Eric. Although I’m on record many times on this site as saying that visual identification is not the answer to determining what a finish is, I think we can make an exception —
Those rocker trim moldings are bright anodized aluminum. Chrome plating is brighter, bluer, less diffuse. It’s best to compare a piece of chrome plating side by side to see the difference. Find a nice Harley and it will probably have both top quality chrome plating and very nicely polished aluminum. You’ll see that even well polished aluminum looks pasty white next to chrome plating.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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January 2018
Q. Thank you, Ted! Can you please explain what bright anodized Aluminium is? How is the shine obtained? Do they polish the aluminum and then anodize it? I am sorry that this is likely a basic question. I am just confused because I thought anodize was a dye that bonded to the surface and was not bright. And, I am surprised if Jeep would polish the backside, which is not visible.
Eric Bickel
– Austin, Texas, USA
January 19, 2018
A. Please see our “Introduction to Anodizing of Aluminum” for a general understanding of what anodizing of aluminum is about. It is possible to manually polish the aluminum before anodizing, or do a nitric-phosphoric acid chemical “bright dip”, or do electropolishing. If the back of the molding is bright, it may have been bright dipped; but again, appearance is usually a pretty weak tool towards figuring out how somethinh was processed.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
January 2018