# Bubbling under paint on aluminum frame



## armstrong (Jul 9, 2013)

Hi folks

I've googled around a bit for info, and although there is some info on this topic, there is not a lot, so I ask here.

I bought this bike used last summer. I believe it's a 2006 frame. I spent the last week doing paint touch-ups on the frame for small nicks, when I noticed the bubbling. I didn't notice this bubbling before so I don't know if it was there when I got it, or if it developed since I acquired it last summer. It basically hasn't been ridden since I bought it and it's been stored indoors, both by me and the previous owner. The cable stop is under the top tube towards the front of the bike, so it would be beneath the head/torso of the rider - presumably would be an area to get hit by a rider's sweat.

Anyhoos - what should I do? Will the affected area grow? It's aluminum corrosion right? Should I remove the affected area and re-paint it? What if I just leave it?

Thanks in advance.


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## mikerp (Jul 24, 2011)

Looks like oxidation under the paint.
So yes to your question. (in simple terms Steel oxidation is called rust).
Chances are it will keep growing, it may start to pop up in more areas.


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## PlatyPius (Feb 1, 2009)

Corrosion from water entry or galvanic reaction with the pop-rivet. If you scrape the bubbled paint off, you'll probably find white powder. Eventually, the cable stops will fall off when the corrosion makes the holes big enough for the pop-rivets to fall out.


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## armstrong (Jul 9, 2013)

So is the aluminum frame corroding or the pop rivets or both? What material are pop rivets made of?


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## Oxtox (Aug 16, 2006)

had a 7000-series Al frame once...

had similar, but much larger paint cancers...a couple of pieces the size of a quarter flaked completely off and the tubing had a nice thick layer of powdery white oxidation on it.

sanded and re-painted a few of the more obnoxious parts, but the repaired areas bubbled up after a year or so.


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## PlatyPius (Feb 1, 2009)

armstrong said:


> So is the aluminum frame corroding or the pop rivets or both? What material are pop rivets made of?




The frame is corroding.
Pop rivets are either steel or aluminum, but usually with a steel center (mandrel).


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