Anodized panels

[unrealmach1]

I have found a few posts talking about anodizing the aluminum panels on a roadster, but I have not seen any pictures of anyone that has done it yet. Has anyone done this and how did it hold up? I really like the anodized look on aluminum, so I am really considering it instead of powdercoating.

[cChrisM]

I had some part anodized and the piece has to be perfectly polished as it shows every imperfection. They can also scratch. Here is an old tread, there are many others. http://www.ffcars.com/forums/40-2003...ry-awards.html

[cChrisM]

Here is another tread with good info. http://www.ffcars.com/forums/17-fact...pros-cons.html

[mikeinatlanta]

Never quite understood the logic of installing a finish that is basically unrepairable on a car that gets driven.

[2FAST4U]

^I agree. Over time, rocks and debris will chip the panels rendering them ugly

[progmgr1]

Looking at this and other threads, there seems to be some confusion out there on the topic of anodizing. That probably is because there are 3 different processes all falling under the general heading of "anodizing".

Type I is commonly called "chromate conversion coating" and is a thin, fragile coating that provides corrosion protection. It's mainly used as a primer under other coatings.

Most anodized parts in military and commercial applications are Type II (sulfuric) coated. This is a relatively soft, thin surface coating (0.0001" - 0.0004" thick) that provides corrosion protection, is somewhat electrically conductive and mildly abrasion / impact resistant. This is a surface coating that can easily be drilled through, but can be scratched or chipped by an errant screwdriver / X-acto knife / stone impact. I would suggest that soft anodizing only be used for cosmetic purposes, maybe on interior panels or trim pieces. Soft anodizing can be dyed in many colors, but can be difficult to color match in paint for touch-ups. Also, the acid etching portion of the process tends to emphasize scratches and dings in the surface that don't get covered by this thin coating, so we would usually ScotchBrite or polish parts to give a uniform appearance.

Type III (hard) anodizing is an entirely different thing. This process actually converts the surface of the aluminum into a very hard and tough ceramic material. The parts will get 0.002" - 0.0025" bigger, and the ceramic conversion extends below the surface a similar amount. A hard anodized surface is VERY hard and will be impervious to tool strikes, stone chips, etc. However, you will need special drill bits or have to grind off the coating locally in order to drill a hole. Also, any holes in the parts - especially threads - will need to be masked before anodizing (most anodize shops will have rubber plugs for this). If not masked, the holes will close down and it's very difficult to chase threads with a standard tap after hard anodizing. Another issue is that hard anodizing is a very good electrical insulator, which can be useful in some applications. Don't plan on using a hard anodized part for your chassis ground though, unless you want to do a whole lot of grinding in the lead clamping area. The hard anodized coating is also somewhat brittle and may crack if the part underneath flexes too much. Hard anodizing can also be dyed, and tends to hide minor surface flaws due to the thick coating.

HTH
Keith

[cChrisM]

Great Info keith, thanks.

[unrealmach1]

Great info Keith.

I really like the aluminum look, so that is why I was thinking of anodizing. Really wondering how it holds up over time.

Good point about touching up coating. Can powder coating be touched up?

[2FAST4U]

No, powder coating can't be touched up with new powder coating. Touch up with paint is the only solution.

[unrealmach1]

I didn't think powder coat could be touched up, but I really have no experience with it so had to ask.