Patching aluminium frame corrosion

[Peugeotrider]

Use etch primer over aluminium.
When it dries,apply a high build primer then prep and paint after that stage.
Car painter 30+ years so I know these things lol

 

[ColinJ]

Am I right in my belief that this kind of corrosion is merely a cosmetic issue?

My aluminium singlespeed bike has similar corrosion, though not as bad as that. The bike was built from a donated frame/fork and from odds and sods of other old bikes and I would rather not spend money on it as long as it is safe to ride.

 

[Peugeotrider]

Am I right in my belief that this kind of corrosion is merely a cosmetic issue?

My aluminium singlespeed bike has similar corrosion, though not as bad as that. The bike was built from a donated frame/fork and from odds and sods of other old bikes and I would rather not spend money on it as long as it is safe to ride.

I would try and push a screwdriver through the corroded area.
If the screwdriver goes through it....chuck it

 

[ColinJ]

I would try and push a screwdriver through the corroded area.
If the screwdriver goes through it....chuck it

It won't do!

I'm just wondering if aluminium corrosion limits itself to the surface or eventually eats its way through the metal the way that rust does to steel? (I think I remember reading that Al corrosion forms a protective layer?)

 

[Peugeotrider]

It won't do!

I'm just wondering if aluminium corrosion limits itself to the surface or eventually eats its way through the metal the way that rust does to steel? (I think I remember reading that Al corrosion forms a protective layer?)

I have worked on cars and vans with corroded aluminium panels but never come across a holed one.
Yes,very badly corroded and weakened but never holed

 

[ColinJ]

I have worked on cars and vans with corroded aluminium panels but never come across a holed one.
Yes,very badly corroded and weakened but never holed

Well, strictly speaking it only has to last one more winter. I will be able to afford a replacement next year.

I'll take a closer look at it and see if it looks worth trying to improve.

 

[keithmac]

I've seen aluminium parts corroded through on motorcycles, if it's continually being attacked by salt it will eventually turn to dust!.

I'd get that cleaned up with wet and dry and a wire brush and see how deep the pitting is.

If not too bad you could smoth it flat with JB Weld or similar then a paint repair I suppose.

 

[davidphilips]

Try using a wire brush attachment (very cheap on ebay a few pounds including delivery) to rub it down first these wire brushes are very quick for cleaning up metal just make sure to wear eye protection. then either diy paint or get it painted or powder coated?

 

[rogerzilla]

I think you were extremely lucky that was the colour of car they were painting that week.

Looks very nice.

 

[Punkawallah]

Oh! Gods! Allegro beige! Nurse, the ‘comforter’! :-)

 

[Illaveago]

I would give it good going over with a wire brush in a drill before finishing it with wet or dry paper. You might be able to get some metal pre treatment acid which will remove some of the corrosion, it contains phosphoric acid. Wash it off and dry it and then apply an etch primer . Upol do an etch primer in an aerosol .
Aluminium oxide does form a protective layer, your frame probably has a higher percentage of magnesium in the alloy . Using Gunk on aluminium makes it corrode like crazy !

 

[Tribansman]

Hijacking slightly...I've got an aluminium framed bike near the end of its life and have a lot of chips and mild corrosion. I have absolutely no clue about all things chemical/material/paint related, but I was thinking of covering them up with clear nail varnish. Is that a ridiculous idea or worth doing as it would prevent further corrosion?

 

[davidphilips]

Yes Tribansman well worth doing just wire brush or sand down the corrosion before applying a coating of paint or nail varnish, know the old saying a stitch in time saves nine.

 

[Mr Celine]

After some further internet research I've found a place in Edinburgh that can bead blast and powder coat my frame for a reasonable price.

I hacked off the worst of the flaky paint and had a good dig at what was underneath with a bradawl. Some bits were very powdery but the underlying alloy is sound enough.

The only problem I had dismantling the bike was with the bottle cage bolts on the underside of the downtube. I don't remember ever having used them. Despite a liberal soaking in plusgas they weren't for turning except in conjuction with the rivnuts. I tried several fixes recommended in youtube videos, but just like Haynes manuals these fixers only seem to work on new machinery.

Some of the suggested fixes recommended cutting the bolt heads off with a dremel, which is what I did. The rest of the processes proved to be superfluous, as the rivnuts were so corroded themselves that the outer half disintegrated once the bolt head had been removed.

There's no way that was ever going to unscrew.

 

[davidphilips]

Easy to fit new rivnuts now you have the old ones removed but if you dont use them maybe just fit blanking plugs after the frames painted?