Scratched Aluminium Frame

General cycling advice ( NOT technical ! )
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gbarton24
Posts: 4
Joined: 29 Jun 2018, 10:16pm

Scratched Aluminium Frame

Post by gbarton24 »

I noticed a small scratch on the top tube of my Cannondale CAADX 105. Any tips on repairing it? You can see the aluminium now
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tim-b
Posts: 2091
Joined: 10 Oct 2009, 8:20am

Re: Scratched Aluminium Frame

Post by tim-b »

Hi
I'd leave it. Aluminium oxidises almost immediately and protects itself; the oxide is hard and doesn't dissolve in water
Aluminium is difficult to paint because you paint onto oxide, even if you paint quickly after cleaning back to bare metal. This makes a special paint system necessary
Regards
tim-b
~~~~¯\(ツ)/¯~~~~
gbarton24
Posts: 4
Joined: 29 Jun 2018, 10:16pm

Re: Scratched Aluminium Frame

Post by gbarton24 »

Ok thanks, i’ve seen recommendations to leave like you said or use nail varnish or auto paint. My main worry is weather damage to the frame more than anything. Aesthetically it’s annoying but I’ll get over that
tim-b
Posts: 2091
Joined: 10 Oct 2009, 8:20am

Re: Scratched Aluminium Frame

Post by tim-b »

Hi
Keep an eye on it but I wouldn't worry. Rinse salt away (seaside? gritted roads?) from the whole bike and it should be fine
Anodising is a controlled oxidising process that incorporates colour into the oxide structure
Regards
tim-b
~~~~¯\(ツ)/¯~~~~
the_twin
Posts: 70
Joined: 11 Mar 2018, 9:01pm

Re: Scratched Aluminium Frame

Post by the_twin »

Get a Sharpie of a similar colour and draw over it.
Mud-Plugger
Posts: 24
Joined: 18 Jul 2018, 9:03am

Re: Scratched Aluminium Frame

Post by Mud-Plugger »

If you look at scratched alloy car wheels, the corrosion tends to creep along under the clear coat and eventually form 'white worms'. It takes a while though.

I use clear nail polish or clear car touch-up paint on scratched alloy frames. A cocktail stick makes a better 'brush' than an er, brush.

You can also get a reasonable paint match for most silver colours from the racks of touch-up sticks in Halfords etc.
Vorpal
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Re: Scratched Aluminium Frame

Post by Vorpal »

Nail polish is a good way to touch it up. I'm sure that with a little effort, you can match your frame paint, or near enough.
“In some ways, it is easier to be a dissident, for then one is without responsibility.”
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rmurphy195
Posts: 2199
Joined: 20 May 2011, 11:23am
Location: South Birmingham

Re: Scratched Aluminium Frame

Post by rmurphy195 »

Humbrol enamel paint? (Cheaper for a little tin of this than car paint!)

Or even a bit of clear lacquer
Brompton, Condor Heritage, creaky joints and thinning white (formerly grey) hair
""You know you're getting old when it's easier to ride a bike than to get on and off it" - quote from observant jogger !
gxaustin
Posts: 890
Joined: 23 Sep 2015, 12:07pm

Re: Scratched Aluminium Frame

Post by gxaustin »

My wife is great at finding nail varnish to match. Sometimes I've had to mix two but the quantities are so small that's not a problem.
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