How to shine up old anodized aluminum?

[robot.hebobo]

Polish a anodised finish?

I’d like to hear the theory behind how that would work.

I know you're being sarcastic but... from what I can tell, 90% of the anodized finish (yes, I know it's a microns thick layer of deliberately created aluminum oxide) is intact, but there are blotches of darker, rougher (?) surface, where I assume further corrosion has happened. Lightly abrading the surface seems to even out the appearance pretty well.

I will try scotchbrite next.

 

[d8mok]

I know you're being sarcastic but... from what I can tell, 90% of the anodized finish (yes, I know it's a microns thick layer of deliberately created aluminum oxide) is intact, but there are blotches of darker, rougher (?) surface, where I assume further corrosion has happened. Lightly abrading the surface seems to even out the appearance pretty well.

I will try scotchbrite next.

Corrosion on top of an anodised finish?

 

[baron von greenback]

Does it look like rain splashes were the anodise just looks darker but looks like a water splash( sounds mad but you know what i mean when you look at it ) but theres no corrosion or damage

 

[robot.hebobo]

Corrosion on top of an anodised finish?

What's your guess then?

 

[robot.hebobo]

Does it look like rain splashes were the anodise just looks darker but looks like a water splash( sounds mad but you know what i mean when you look at it ) but theres no corrosion or damage

Yes, pretty much.

 

[baron von greenback]

I got the same thing on a set of scott matheures hydrostop brakes thought something had been spilt on them i was going to try cleaning products starting hot soapy water and work my way up is there anything under it when you sanded it may be i was wrong but thats was my thought rather than corrosion or rust because mine have no chips scratches so cant see how anything got in

 

[baron von greenback]

Also i was looking at anodising polish them who make autosol have one its in a tube and metallique thats a liquid if i right

 

[d8mok]

What's your guess then?

Without inspecting or seeing them it’s hard to say.

But purely by the nature of anodised alloy it cant be either option you’ve said.

Are they clear anodised over a polished or bare base? If so , remove the ano , and polish and get reanodised.

 

[robot.hebobo]

Without inspecting or seeing them it’s hard to say.

But purely by the nature of anodised alloy it cant be either option you’ve said.

Are they clear anodised over a polished or bare base? If so , remove the ano , and polish and get reanodised.

I'm not sure, I'm new to trying to restore an older bike like this. I tried to take some clear photos.

The parts are all 1991 Deore XT, so the original finish is probably familiar to everyone here.

Here's an example of the blotchiness:


This brake arm was lightly rubbed with the '0' grade wire wool, and the the finish is duller but more consistent. If you don't look super close, it looks reasonably like the original finish, that I remember:


The front derailleur clamp was polished with Simichrome. It's extremely shiny (shinier than new, IIRC), but the blotches are obvious:

 

[robot.hebobo]

For what it's worth, I've no intention for this bike to look brand new - the overall condition of all of it is too rough anyway, and I'm going to ride it. I'm definitely not getting parts re-anodized. I'd like it to look as true as possible to how it looked in the early 90's, but that will include looking like it's been ridden