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enter image description hereI'm not sure if a lot of people do this, but I want to remove scratches from my Shimano Dura-Ace crank (caused by a slipped chain). The way I want to do it is to repaint the crank (just the chipped part) in multiple layers, sand the part and apply polish just like how people deal with chips in cars. Here are some main questions:

  1. Is that an viable solution and are there other way?
  2. What's the color/color code for the black crankset?
  3. Can I sand the whole crank? Will it cause an issue for the logo? I want to reduce the difference between the part I painted and the original paint.
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  • Welcome to the site - Can you add some photos of your cranks for context? Use edit
    – Criggie
    Jul 31, 2023 at 18:27

1 Answer 1

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One problem is that the crankset is anodized black. Strictly speaking, anodization is when we use electric current to change the thickness of the oxide layer at the surface of a metal like aluminum. When we talk about anodizing aluminum, we can also impregnate the oxide layer with dyes - basically the dye sits in the pores in the oxide layer. It’s then clear coated. By comparison, with paint, you have a primer layer and then one or more layers of paint on the metal surface, then a clear coat.

Thus, if you just paint the area round the scratches, I believe you won't match the thickness of the anodizing layer in the area. When you sand/buff it to finish, as you would with wet paint on cars, you'd risk sanding through the clear coat on the anodized portion.

Back to the crank, I don’t think you could replicate the color by just painting. You could use drain cleaner to remove the anodization, or at least the dye layer. I think this is preferable to sanding the top layer off. You’d then be left with a silver crank. You could smooth the scratches with sandpaper, then decide what to do with it. A shop called Cycloeretro in Australia does this to various metal groupset parts and it polishes them, old school style. This sounds like an immense amount of effort, though.

Basically, I am skeptical that you would achieve great results. Dura Ace is a racing group, and it is not the worst fate for it to have some signs of heavy use.

Side note: titanium can also be anodized. However, color is generated by an interference effect. No dyes are involved in ti anodizing, and you can only get a limited range of colors.

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    Good answer. As you pointed out, anodization leaves a translucent layer over the metal--opaque black paint isn't going to look the same. Also, I would not recommend applying drain cleaner to strip the ano. There is a risk of damaging the adhesive which holds the cranks together. We've all seen photos of what happens after that. I would imagine the Australian shop only does this polished finish to solid metal parts.
    – MaplePanda
    Aug 1, 2023 at 19:55
  • ahh thanks for the reply, I guess ill just train harder with my bike with slightly less concern for scratches haha
    – Jas0n
    Aug 2, 2023 at 14:25

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