Aluminium Corrosion questions

chamelion said:

I was giving my Giant a polish up the other day and I noticed what looked like a couple of "rust bubbles" in the paintwork, on the seat tube and more on the top tube. I was able to scratch off the paint easily and along with it the white corroded aluminium. The corrosion wasn't deep, doesn't look critical, but makes me wonder how it occured and how I should treat the bare metal now?

Is this an electrostactic thing? Electrolisis? What do you people think I should do to treat the bare metal?

Aluminium does oxidise, but the oxide it forms acts as a protective layer not allowing anny oxygen to get to the aluminium underneath. Apart from looking nasty, it should be ok.

chamelion said:

I was giving my Giant a polish up the other day and I noticed what looked like a couple of "rust bubbles" in the paintwork, on the seat tube and more on the top tube. I was able to scratch off the paint easily and along with it the white corroded aluminium. The corrosion wasn't deep, doesn't look critical, but makes me wonder how it occured and how I should treat the bare metal now? ...Is this an electrostactic thing? Electrolisis? What do you people think I should do to treat the bare metal?

How it happened is a mystery; there could have been a contaminant before the paint was applied, or the paint could have had a defect (a broken bubble or a crack or scratch) that collected sweat (salt + water will corrode aluminum).

How you treat it is--you put on some rubber gloves, wash the area off with warm water and dishwashing detergent, rinse well with warm clean water, dry it with a hair dryer or very brief use of a heat gun until the metal is dry and warm, and then paint over the bare metal with your chosen enamel as it cools.
~

Thanks for the replies 🙂

The frame is yellow so I think I'll use green paint, I like green, and if it keeps corroding I will get a tree snake out of it in the end 😉