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I have an old aluminium framed mountain bike which has developed some 'oxidation / corrosion' underneath the lacquer -- it kind of looks like little white worms!

The frame as original has a nice smooth, ball-burnished finish (it looks like brushed steel but on aluminium), so whilst I could have the frame sand-blasted this would leave it with a dull finish.

Does anyone please know of a way I can treat the frame such that it will strip the existing lacquer, decals and oxidation marks but leave the original smooth finish intact?

Failing that is there an 'easy' way to restore the polished finish after sand-blasting?

I realise that the simplest solution would be to blast the frame and then paint it, the dull finish from sand-blasting proving a good surface for paint to key to.

++ Thanks ++

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There's a few approaches you could take...

I'd say that getting it blasted should be the first step no matter what as chemical strippers can damage alloy frames are very messy and really bad for the environment.

Give it a polish with some very fine grit wet/dry paper to polish up the alloy.

Then you could use one or a combination of the methods below to get the kind of brushed look that you are after. Whichever gives the desired finish the best.

Tip Get a scrap piece of alloy to test brushing technique on before commiting to attacking your frame. (if you mess up badly you could always reblast or repolish the brush out of it.)

Option 1. (carefully) use a wire wheel drill bit go over your frame

Option 2. by hand with a scotchbrite / scouring pad to go over your frame to get the desired brushed look

Option 3. 000 or 0000 grade Wire Wool then carefully do long straight strokes down the frame.

Once happy with your finish don't get fingerprints anywhere on the finish or they will show through the lacquer.

Clear lacquer the frame locking in the brushed finish. Thin laquer = no drips

Depending how shiny/durable you want the lacquer increase the amount of coats and let it completely dry. Polish with a clean microfiber cloth between each coat. repeat until happy.

Hope that helps.

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The solution is to sandblast it. Then polish the aluminum with a metal polishing compound before repainting it with a clear finish.

This is easy, if detailed and time consuming work.

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  • 1
    John Allen suggests not to do sandblasting: sheldonbrown.com/paint-prep.html
    – Batman
    May 18, 2016 at 17:49
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    There are other options for blasting - a competent blaster may recommend something other than sand, like nylon beads, sawdust or even walnut shell. Blasters who specialise in vintage car parts will have expertise in this area.
    – Criggie ♦
    May 19, 2016 at 2:41

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