Achieving a 'mirror' finish on an Aluminium Frame

[90sMTB]

I have recently acquired a '93 Marin Rocky Ridge for doing up. It has a 7005 Aluminium frame but is mottled to hell with oxidation pretty much all over. In places you can see it's original shiny finish and I'd like to get back to that if possible. Any ideas how?

I used a bit of fine wet&dry on a test patch but as well as sanding off the spotting it left the frame generally 'matte' with silvery powder everywhere so I stopped in case I was causing any damage. Is this normal prior to further treatment or have I ruined it?

Any tips on how to restore to its original shine gratefully appreciated! Cheers.

 

[RickTheUncivil]

Plenty of threads on the topic, search the forum pages (near the top right of the page) and you will find plenty of useful info

 

[legrandefromage]

Its lacquered - thats what you are sanding at the moment. You need to strip it first, then polish it.

 

[90sMTB]

I've read plenty of threads on this site but none that specifically address the all-over mottling, or seem to concern frames like mine. I don't even know what needs stripping on this particular frame. I (perhaps mistakenly) assumed it was already bare metal, but just highly polished so if the horrible silvery powder is lacquer, how will I know when I'm through it and down to the metal? I'm paranoid about sanding too much of the metal and weakening the frame. Aslo do I use the wet and dry wet or dry? Is there a household product I can use to safely remove the lacquer without sanding? Guys, you're dealing with a real noob here!

 

[Thias]

I use a metal sponge (very finde) to remove the laquer and the finer scratches. For the bigger scratches I use sanding paper of different grades depending on how deep I have to go. In the end I use wadding polish (NevrDull atm) to get that shine.

Using Water with the sanding paper or not is up to you. If you use Water, that will make the grain of the sanding paper stick on the metal a bit longer, thus making for a finer grit.
You would need to do that If you were to polish laquer, not metal.

 

[PaintedDesert]

Have a look here for some good advice: viewtopic.php?f=6&t=371827

Don't worry too much about weakening the metal, if you're not using a machine with very rough paper, that won't happen.

The final step is always something like Autosol. Only then will it start to shine.

 

[90sMTB]

Thanks for your suggestions folks, I definitely have more of an idea what I should be doing now. I'm mechanically minded - good with moving parts; paint jobs/surface finishing is a new thing for me as I've normally just frankensteined bikes so they run beautifully rather than looking great... This lovely Marin frame was just begging to be brought back to life!

PaintedDesert, thanks for the link I missed that one. My frame looks EXACTLY like that one, if anything not as bad so that's encouraging!

I've heard of a few polishes, such as autosol and mothers but was wondering if the Brasso or Silvo that I have already under the sink would produce the same results?

 

[xerxes]

Re:

I've heard of a few polishes, such as autosol and mothers but was wondering if the Brasso or Silvo that I have already under the sink would produce the same results?

I've achieved some pretty good results with Brasso, you can see I've still got some marks left; I ran out of patience:

 

[90sMTB]

Re: Re:

I've achieved some pretty good results with Brasso, you can see I've still got some marks left; I ran out of patience:

Wow, that looks really nice.

 

[dongward]

My old flatmate used steel wool on his Zaskar and that came up quite nicely. If using steel wool it may remove the lacquer but shouldn't damage the frame (stripping the lacquer seems the thing to do first!). I have in the past used wet and dry on a set of cranks and gave up on them as I was doing it by hand and simply lost the will to live trying to get it polished up so beware! Though you seem more sensible than I was...

I'm in a similar scenario but with chrome and there have been mixed comments about using steel wool, brass wool or just metal polish. That's a different kettle of fish though as the chrome can be stripped off if not careful - that doesn't apply here.

I'd follow the stripping steps in one of the links above - seems like good advice!