davester

OK, I realize that there are a zillion posts and articles out there in internetland describing how to remove the anodizing from aluminum bike parts so that they can be buffed to a brilliant shine. However, there don't seem to be any descriptions of how to improve the look of beat up anodized parts short of removing the anodizing Is this because its impossible? My campy cranks have quite a few well-earned shoe scuff marks and plenty of derailed-chain marks, but I would rather keep the anodizing as god and Campagnolo originally intended and don't really relish the thought of trashing that original anodized finish. Any thoughts on improving the look without resorting to oven cleaner, sandpaper and the like?

DMC707

Anodizing is a sacrificial finish -- when its gone, its gone. Strip it and re-anodize it --- or strip it and polish it, but the reason anodizing came in vogue is because a polished finish needs constant attention --- OK on a show bike or a wall hanger , but a PIA for a bike in the field

Jaredn

Anodized parts are chemically/electrically treated to change the surface composition of the metal, so that it can more easily accept a dye.

So really, your choices are limited to (I'm assuming, could be wrong): strip it and polish/paint it, strip/re-anodize, try to find a paint or dye that matches it close enough so nobody notices.

verktyg 

Aluminum anodizing is an electrochemically applied layer composed of of aluminum oxide.

Anodized surfaces range from less than .0002" to over .005" thick (0.005mm to 0.127mm).

If you take virgin aluminum and expose it to air, it will immediately start to oxidize and form a layer of aluminum oxide which is what gives it a degree of corrosion resistance.

There are a number of reasons for anodizing aluminum. It provides increased corrosion resistance plus adds a measure of scratch resistance, then there's is the cosmetic factor.

There are an number of different anodizing processes and results depending on application. Chemical dyes are used to color anodizing.

A quick Google search will bring up a lot of sites where you can find out more about anodizing.

Here's a good starting point:

https://www.omwcorp.com/understandingano/anoindex.html

To answer your question:

Because the thickness of the anodizing is so thin, it's difficult to measure the surface hardness but aluminum oxide is one the hardest man made material.

There's not too much that you can do to clean up an anodized surface short of striping and re-anodizing.

verktyg

Chas.

easyupbug 

All I know to do is accept that the part has a patina that I can live with and so strip and polish or re-anodize is out of the question. Part looks just as it should after that decision.

eschlwc

not my experience.

every once in a great while, i'll need to buff a seatpost for twenty seconds that has developed a smudge. and that's it for all the polished campy components on my keepers.

davester

So no hope, eh? I wasn't thinking that I could entirely remove the patina, but I thought there might be a way of dressing up the chain marks on the crank end where it meets the spider.

smontanaro 

You could send the crank out to be re-anodized. Or do it yourself.

gaucho777 

I haven't tried this on a small spot, and doubt you'd be able to blend it in entirely, however...it is possible to introduce a satin finish to a polished alloy part by gently rubbing the polished part with a scotch-bright pad. I've done this a few times to complete parts such as Cinelli stems which usually have a nice anodized finish, but look odd to my eyes when polished to in a mirror finish. The technique is to first polish to a mirror shine, then finish by "polishing" in perpendicular strokes with a scotch-brite pad, and finally top with a layer of wax. You may try that on the spots with shoe rub, just try to avoid the areas where the anodizing remains. Not a permanent fix, or likely to blend in completely, but may be worth a try.

tashi

gaucho777 just beat me to the punch.

His approach allows you to decide if you'd prefer to stop and wax at the polished stage. I often contemplate stripping etc, then am fine once things are all cleaned and buffed. Wax is a good idea I haven't tried.

kevins08 

You can remove the anodizing with Easy-Off oven cleaner, or caustic soda. I have done the former on anything from chainrings/cranksets to Surly Large Marge Rims. Works great, takes about 15 minutes. I usually wipe it all off a bit before its ready and use a 2nd coat to finish, you dont wanna go to long or the aluminum actually disintegrates as well. Finish it up with Mothers mag polish and it looks great. Or reanodize if you prefer.

gugie 

You can remove anodizing and re-anodize, but it will probably look like crap unless you're willing to hand-polish after the anodization strip. If you just do a chemical strip and re-anodize, it'll probably look very mottled aftwards. That's been my experience at work.

verktyg 

Use the gray Scotch Brite 7448 Ultra Fine pads. XXX or XXXX steel wool will leave a satin finish too.


verktyg


Chas.

wrk101

Strip and polish. I use dollar store spray oven cleaner. Do it outdoors, wear gloves and eye protection. Its nasty stuff!!!

rootboy 

And then, apply a good paste wax.

Gaucho's idea about applying a light satin finish is a neat one. The best tip is like he said. You have to take the part up to a mirror shine, then back down with your scratch pattern.
Having worked a bit with metals, I'll say it takes a good hand to do it well though. To get all the scratch marks lined up and in the same direction, so it doesn't look random, and bad.
For this procedure I have a very fine brass wire 4 inch wheel I put on my buffer. It's made for just this sort of thing.

davester

Those are nice tips for flat surfaces, but I was mainly trying to figure out how to touch up the gouges from where my chain has landed on the inner crank arm end after overshifting. I don't think the methods described will work. Perhaps I'll post a photo later of what I'm talking about.