I'm redoing an old BMX-style handlebar, but its been treated badly and there is rust under a lot of the chrome. Its not saveable, so what is the best way to remove the chrome so I can treat the rust?

Ideally I'd get it shotblasted, but what else can I try first ? I have tried:

  • Manually scraping with a knife - the bars are round and curved so a flat blade only clears a very narrow line.

  • Spinning wire wheel/wire cup on a drill - works but slow and tedious, and makes a mess of little slivers of chrome.

Is there a liquid soak I could use to get under the chrome?

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  • The flakes of chrome are thick- equivalent to 3 layers of paint. A big piece might be 25-50mm /1-2 inches long and 5-6mm/quarter-inch wide, but most of the flakes are under a millimetre wide and at most 2-3mm long. Its mostly caused by weathering and poor storage, the chrome under the grips is perfect. – Criggie Oct 23 '16 at 20:13
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    Chrome is applied to steel using an electric current. In essence the chrome is "welded" to the steel. There is no chemical that will remove it. However, oxalic acid (sold as "wood bleach" in paint stores) will dissolve rust and might loosen up the chrome which is undercut by rust. – Daniel R Hicks Oct 23 '16 at 21:35
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    Naval Jelly (phosphoric acid) is another option, even though its not intended for chrome. Oxalic acid is also sold as Barkeeper's friend in the grocery store. – Batman Oct 23 '16 at 21:48
  • @Batman I tried phosphoric acid - I had "Rustbuster" on hand which converts red/brown rust into stable black iron oxide. This didn't do anything to the chrome, so I suspect its back to mechanical means to strip any loose chrome, and to key the chrome that is still firmly attached. – Criggie Oct 24 '16 at 6:14
  • The chrome that remains well adhered doesn't want to scratch so any paint I might apply will simply run off like raindrops on glass. Looks like its a stripper wheel or whittle it off with a sharp knife over a bin. – Criggie Oct 25 '16 at 6:37

In the end I had success using a grinding wheel and a 100mm / 4" grinder to remove all the slightly loose chrome. The good chrome under the grips simply wouldn't move, so ended up being ground off by the grinder wheel.

This left a terrible surface, with many small flattened patches and diagonal scoring. It was no longer round. I spent a half-hour with 80 grit sandpaper, then 160 grit then 400 grit paper.

It was a slow process, and ultimately finished, it was no fun at all.

Then I immediately primed the bare steel to prevent any further rust from developing on the virgin steel surface. On top of that I will put several coats of black spraypaint, and then a couple of clear topcoats.

I didn't get a photo of it before painting, but here's one showing one coat of primer. Looks like its been peeled with a vegetable peeler, then zoom in to see the scratches in the "around" direction.

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Final edit - here's the finished bars on the scooter. That's two coats of primer, two top coats, and one clear coat on top.

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Check out the zoom on this one: enter image description here

The Stem Cap is alloy and it had white aluminium oxide "rust" , so the same treatment has left a different look. I left the four offset stem bolts chromed and unpainted, because in my experience painting nuts and bolts is a waste of time.

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    It'd be good to see the finished article when it's done then. – Chris Oct 29 '16 at 8:18
  • The grinding wheel made dust instead of flakes of chrome, which was good. However holding it for extended duration made my right arm muscles ache. Not a limb that cyclists tend to develop muscles in! – Criggie Oct 30 '16 at 9:02
  • @chris Done. The rest of the frame is not particularly good, but its a work in progress. – Criggie Nov 4 '16 at 7:35
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    I am a little curious as to why you put so much work into this. There's a pile of handlebars of that style out behind the place where I rehab bikes. They're a dime a dozen (almost literally). – Daniel R Hicks Nov 4 '16 at 11:36
  • @DanielRHicks Reasons - Its a tall set of bars, the ones at icecycles were comparatively low-rise from kids bikes. The scooter is an adult one, so I didn't want to loose height. Also, I have a similar de-rusting task next for a button panel from an arcade games cabinet, and wanted to practice some techniques (learned that grinding would be bad!) Finally I work on-call one week in four - I have to be at home all week and have time to burn. Minor: reuse is better than replacing, from an environmental perspective. Plus its kinda fun, and rationalises owning many tools (and buying more !!) – Criggie Nov 4 '16 at 22:59

The second comment above is correct. This is something that needs to be done in a shop that plates chrome. This is often done for old car parts. I've never done it, so I don't know what it costs. It wouldn't make sense unless the part you are replacing is an original bar on a classic (or dear to you) bike. Otherwise you should just get a new bar that's as equivalent as possible.

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    Yeah if I cared about originality then I'd pay for it to be done properly. But this is rehabbing stuff, so while its worth investing time, its not something to pour money into. – Criggie Oct 24 '16 at 6:12

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