Aluminium - how long does it last?

[aberal]

As per the topic title - how long does aluminium last? I'm thinking of frames here and asking specifically because my 10 year old Cannondale has developed small bubbles of apparent corrosion on the seat stays. But aluminium doesn't corrode. Does it?

 

[Norm]

If it's good enough for aeroplanes...

Aluminium does corrode but it is very resistant to corrosion, much more than steel and the aluminium oxide which forms when it corrodes is actually a pretty good barrier against further corrosion. That means you might get a thin (measured in nanometres) layer of the oxide on the surface of exposed (unpainted) metal but that layer acts as a barrier to stop it going any deeper.

 

[tyred]

As Norm says, exposed aluminium develops a coat of protective oxide very, very quickly and it is nothing to worry about.

If it forms into scaly, powedery corrosion after contact with salt or something, then it may be a bit more serious.

 

[GrumpyGregry]

DC-3/C-47's from the 30's & 40's are still in aviation service around the world.

Your frame may well have a lacquer coating. It may be the lacquer that is bubbling, moisture (and hopefully not the dreaded salt) may have got under the coat.

 

[aberal]

Thanks, guys. The frame does have a lacquer coating so that would make sense if it is that bubbling up.

 

[henshaw11]

I've had a 3 Cracknfail frames (ok, only one of them actually did that), the road frame seemed to do this a lot more more than the original (cracked) mtb frame or it's replacement (FWIW paint then - late 80's/early 90's - was Imron..fell off chainstays that got any chain-slap :/ ).
I *think* it's just the result of some impurity left on surface - a bit like road salt on unfinished motorcycle engine blocks tends to send them furry.

Not sure what the best thing is, but something like: remove blown lacquer; take some metal polish to ally with a cotton-bud to remove impurity (or mebbe a scotchbrite pad - aka green sink scrubbie - depending on the existing finish); clean with meths, leave overnight (the ally should reoxidise, dunno how long that really takes tho) and spot back in with lacquer.

I imagine it actually looks far worse than it is - istr removing the paint bubbles and finding not a fat lot of difference between that and the surrounding ally.

 

[battered]

Ally does corrode but normal painting will fix it. Scrub off the powdery corrosion (as with rust), apply a primer and a topcoat. Alternatively do what I did, get the frame blasted and coated, £30, looks fab and is good for another 10 years if I don't break it.

 

[snailracer]

As Norm says, exposed aluminium develops a coat of protective oxide very, very quickly and it is nothing to worry about.

If it forms into scaly, powedery corrosion after contact with salt or something, then it may be a bit more serious.

Unfortunately, that is only true of pure aluminium. The aluminium alloys used for bike frames or aircraft corrode and weaken quite readily when exposed to road salt, forming the powdery stuff you mention - keep the lacquer or paint intact to stop the frame from being seriously damaged.

 

[silva]

As long as a ladder probably.
Never looked it up, but I consider it likely that same aluminium containing materials are used.
I have a ladder outside exposed to all weather since almost 40 years. Can't see any material degradation.
10 years ago I used a worn chainring for an application in the garden. Same.
Aluminium powder means material dissolved, galvanic corrosion. Happens when electrical contact with bigger amount / much more noble material (alike stainless steel). Can't see how a bike frame could suffer that, since the amount aluminium in a frame is far more than any stainless/more noble part alike a bolt or screw. Also, the corrosion detaches/removes aluminium, resulting in play, less electrical contact, so it should decrease/stop over time, and the play should have noticable bike behaviour change results.

 

[cyberknight]

my 2011 boardman developed bubbling around the bottle cage holes on the down tube , i chipped the bubbled paint off and the metal was fine .In the end i got the frame resprayed and its still one of my favourite bikes .

 

[Ajax Bay]

Well done @silva - you found a thread over ten years old.
Anyone want to identify a lengthier resurrection?
@tyred is still around.

 

[classic33]

Well done @silva - you found a thread over ten years old.
Anyone want to identify a lengthier resurrection?
@tyred is still around.

Check the first similar thread at the base of the page, then see what the first similar thread is on that one.

 

[Seevio]

Nothing like thread necromancy. As the OP is no longer around, we have to conclude that bubbling on an aluminium frame may be fatal.

 

[ColinJ]

Sorry - I misread the title... I thought it was "Aluminium - how long does this [thread] last?"!

 

[classic33]

Sorry - I misread the title... I thought it was "Aluminium - how long does this [thread] last?"!

Longer than a used tyre, now carried as a spare.