Polished Alu frame weatherproofing

[duncan]

The paint on my aluminium mountainbike frame was starting to bubble up quite badly, so I stripped all the paint off.
Water & roadsalt gets under the the paint where it's scratched and oxidises the metal.

I'd like to polish the frame, and wondered how I could treat it afterwards to preserve the finish.
I know some of you have polished PK Rippers, and I'd like the same finish, but don't want to have to buff it every week to stop it dulling - it's a very big frame

Will it hold its shine for a decent length of time, or will I need to lacquer/clearcoat it?
I read on a biking forum that you can use wax. Sounds messy, but anyone tried it?

I went as far as buying a can of acrylic spray lacquer, but maybe someone may recommend a proper professional lacquer spray.
I also have the same problem with the forks (though they're cr-mo). Thanks.

[rsdan25]

  it would be better 2 put a clear coat i would have fort may b worth gettin sum 1 2 paint it  in a 2k type clear coat  pop it down 2 yr local paint shop

[duncan]

Yes, less maintenance in the future.
Just checked the local Yellow Pages and there are a couple of companies nearby that may do this. Powdercoaters anyway.
I'm tempted to try it myself, but by the time I've bought all the rattle-cans I'd be approaching the cost of a proper job.
Plus a homemade finish would wear or chip almost immediately.
If I thought I'd get a few months out of a polished finish I might just leave it bare. The forks will definitely need coated though.

[rsdan25]

if u get the frame wet  when its bear and leave it . this will stain and thats a pain in the arse 2 pollish out
 

[theRuler]

i polished my ripper months ago. months and months. i cant remember when it was! christmas time maybe

anyway i havent touched it since

if you are riding through mud and shit give the bare ali a good waxing. then keep it clean. and thats it.

[duncan]

Thanks for the info,

Will give it a try with the wax (any car wax/polish?) but as the bike often has to sit out in the rain I may go for a clearcoat if the price is reasonable.

[sawzall]

i wouldnt clear coat it,alloy oxidises and will lift it after a period of time like it does to chrome plate on alloy

[duncan]

I did spot a few areas of bubbling where there was no external paint damage,
No idea how this happens, maybe the paint's thinner, or not stuck to the frame properly.
As you say, it oxidises from underneath and pushes the paint up.

There's always anodising, but for a frame that size.. Might cost more than the frame's worth?

[theRuler]

any wax or polish will do.

brasso it!

[duncan]

Ah, Brasso! Not used that in decades, but I can still remember the smell

I've spent most of today (and most of my spare time over the past week) sanding and polishing the frame.
Never again. Ever. I'd no idea how much time & effort would be involved. Hands so sore I can barely hold a beercan.

The frame had paint keying scratches on all the tubes, they took an age to remove. I had to use 80 grit aluminium oxide paper (no power tools here I'm afraid..)
Then it was onto 120 grit to start smoothing off the tubes. There was a fair bit of white powdering (oxidation) and some minor pitting.
I didn't seem to be making good progress, and decided to concentrate on one area at a time, going through the grits.
Strangely I found the 240 was taking off more surface metal than the 120, I could see smooth metal underneath now!

Best purchase by far was foam rubber aluminium oxide sanding blocks, ideal for sanding & polishing round the tube junctions, also great for rubbing away scratches round awkward points like brake mounts where you haven't got the access to apply any pressure using normal wet & dry. They worked so well I almost won't need to use the finer grit papers.

Will sand the frame wet tomorrow using 800 then 1200 paper, and if I've time I might get it polished too. I got some stickers to put on from Ebay - 'brushed aluminium' stickers on a polished alu frame, I'm hoping for the same effect as one of the bikes in the museum.

[sawzall]

do you mean this one,i polished it in feb and not touched it since,still as shiney

[duncan]

That's the one!
Gorgeous welds on that Ripper frame.

The Cannondale frame I'm working on blends the weld into the tubes, the frame looks almost as if it was cast as a whole unit.
So no nice beading to polish up, but I hope it'll still look good.

My Dad reminded me that the Cannondale lifetime guarantee for the frame probably just went out the window. Never thought of that before I started.
I've almost finished the wet & dry now, may get it polished tonight.

[duncan]

Finished the polishing. Still needs waxed, but I wanted to see how it looks built up first. Hope I can wax over the rub-on decals without lifting them.
In this state, the frame gets marked extremely easily, and as someone else remarked it's very difficult to polish out any grease smudges.

I decided to put on some black decals instead of the silver, I could change them at a later date.
The forks are Cr-Mo, stripped, de-rusted, polished then lacquered. The Simonez acrylic lacquer from a can looks fine, not sure how durable it will be.
I coated another Cr-Mo stem (not shown here) in Plasticote clear lacquer, and it has crazed, no idea why, sudden temperature change?

Put on some GT bars and a Redline Forklifter, it remains to be seen whether the bars will be too high when the wheels are on. Might have problems fitting the brake levers and gear shifters too.
Just for fun, but if it works I might keep it like this for a while

[sawzall]

nice job mate