Polishing Alloy to a high gloss with Sand Paper

[Dave_B]

I’ve got covid, I can’t ride and I’m bored. So I’m going to try and bring my raw frame up to a higher polish.

I’ll them coat with Ceramic before the oxidation sets in and ruins the gloss finish.

I’ve got paper from 800 grit all the way up to 5000 grit and a soft interface pad for the orbital polisher.

What lubricant should I use? Just water or something like MO94 or bike protect or something else?

I watched a YT vid of an Mercian doing some alloy polishing and he used an Allu Cut spray.

 

[jimbob]

Personally I think you'll struggle to get all the top coat off of that with sandpaper and you may end up with quite a mess on your hands... Will ceramic work as a top coat? I'd have thought you'd need a clear coat to work. Either way, you'll need to use a cutting compound once sanded to polish it up.

Perhaps just wet and dry it with a a fine grit to get rid of any orange peel and then polish the existing top coat?

Either way, please take lots of photos and post them up whatever you do!

 

[Hattori-Hanzo]

When you say "higher polish" are you talking about buffing the pre-existing top coat or sanding back to bare aluminium and polishing from there?

 

[jimbob]

I'd suggest just buffing the existing top coat. I recon you'll regret trying to get it back to bare aluminium and trying to polish it. Unless you have a LOT of time on your hands!

 

[Dave_B]

The pics I posted are of my bike. I have already stripped it to bare alloy and polished it. I think I can get a better level of finish if I use fine sand paper, to get the imperfections out and then a liquid polishing compound (which I ready have).

So simply asking what’s best to use as a lube when using 2000+ grit on alloy?

 

[Doomanic]

Does it need much more sanding? Surely getting stuck in with a mop and polishing compound is the way to go now?

I once mirror polished some motorcycle brake callipers with a sisal wheel and a mop on a bench grinder after using Nitromors (when was still good) to get the paint off first.

 

[Hattori-Hanzo]

Fair play to you, that must have taken some work! did you strip the bike apart?

From the pics it looks like you've achieved a good finish. If you want to refine it then as you've suggest wet sanding up to 5000 grit and then buff with a fine compound will have it looking like a mirror.

water alone is fine for wet sanding.

 

[Dave_B]

I stripped the bike and then had the frame dipped over night in a hot dip tank by a local alloy wheel refurber

 

[Dave_B]

Does it need much more sanding? Surely getting stuck in with a mop and polishing compound is the way to go now?

I once mirror polished some motorcycle brake callipers with a sisal wheel and a mop on a bench grinder after using Nitromors (when was still good) to get the paint off first.

Yeah. Up close, it has lots of lines and imperfection. I only used a cutting paste when I originally did it.

 

[steve_sordy]

I too believe that water with some fine wet & dry abrasive will do the job.

When I was an apprentice, back in the late 60's, we used paraffin when machining aluminium. But that was before Health & Safety! Do not try this at home!

I just found this on Google:
Is WD40 good for cutting aluminum?

Almost anything that cools the cutting edge and provides some kind of lubrication will work. You can use WD40, vegetable oil, engine oil, Vaseline, KY jelly, etc. One thing that does not do very well is plain water.

And this: "How to polish Aluminium"

How To Polish Aluminum: The Full Guide

 

[RustyIron]

What lubricant should I use? Just water or something like MO94 or bike protect or something else?

Water is good, but add just a little dish soap to make it a little wetter. Addition of alcohol will have a similar effect, but soap is cheaper.

 

[Doomanic]

Just watched this;

I'm surprised at the finish achieved with the sanding pads; every day is a school day.

 

[jimbob]

The pics I posted are of my bike. I have already stripped it to bare alloy and polished it. I think I can get a better level of finish if I use fine sand paper, to get the imperfections out and then a liquid polishing compound (which I ready have).

So simply asking what’s best to use as a lube when using 2000+ grit on alloy?

Ah, fair enough then! Sounded like you were about to sit down with some sand paper and have a go!

Water and washing up liquid should work. That's what I've always used anyway.

 

[Dave_B]

Just watched this;

I'm surprised at the finish achieved with the sanding pads; every day is a school day.

That’s what I watched.

 

[Ou812]

I polished my old GSXR frame just using sandpaper. I started wet sanding with water once I got up to the 1000 grit and finished off at 5000 grit. It looked like chrome once it was finished but took forever! I also used Meguiars NXT polish afterwards to keep it shiny and somewhat protected, otherwise it would water spot really bad anytime a drop of water hit it.

 

[A06]

I use to do this to all of my dirtbike swing arms, always had great luck with the 3M green and red scouring pads on an angle grinder. FWIW as a machinist we used toothpaste and denim for high polish finish on lathe work. I had mixed results using toothpaste with the red 3m pads, seems to work better with a buffing surface vs a scouring surface.

 

[Dave_B]

I polished my old GSXR frame just using sandpaper. I started wet sanding with water once I got up to the 1000 grit and finished off at 5000 grit. It looked like chrome once it was finished but took forever! I also used Meguiars NXT polish afterwards to keep it shiny and somewhat protected, otherwise it would water spot really bad anytime a drop of water hit it.

That’s why Im going to ceramic coat it.

 

[A06]

Are you using a DIY product such as cerrocoat? Thought about doing this in gloss black but would need to build a curing oven to get entire frame done.

 

[dobbyhasfriends]

The pics I posted are of my bike. I have already stripped it to bare alloy and polished it. I think I can get a better level of finish if I use fine sand paper, to get the imperfections out and then a liquid polishing compound (which I ready have).

So simply asking what’s best to use as a lube when using 2000+ grit on alloy?

done it loads, I usually use water with a very very small amount of fairy liquid in it. go up to 2000 grit paper before going onto polishing compounds

 

[Dave_B]

Are you using a DIY product such as cerrocoat? Thought about doing this in gloss black but would need to build a curing oven to get entire frame done.

I have Gtechnique bike ceramic

 

[Dave_B]

Bike Ceramic - Gtechniq

Bike Ceramic has been formulated to minimise adhesion of foreign objects such as brake dust, road grime and mud. Offers up to 24 months protection.

www.gtechniq.co.uk

 

[Dave_B]

Experimenting with bike polishing today. Took the seat stay off to see how easy it is to machine sand it up to 5000 grit and then polish. Wasn’t too bad. The hardest bit is the final buff, I don’t have a good enough buffer.

I then did the other side to see what a brushed finish would look like. Brushing takes a lot longer and would never be perfect. I used 800 grit paper to brush but will also be trying a scotch pad.

Not sure which would be easier to ‘refresh’ when the time was needed.

Ceramic coating would b applied to either finish option.

There are still lines on the polished finish. Not sure I would ever get it 100% right (with either finish).

 

[Bomble]

I used to mess around trying to mirror polish motorbike parts years ago, I then found a local professional polishing company. The finish they achieved was incredible and pretty cheap really for the work involved.

 

[EMTBSEAN]

I’ve polished aluminium rocker covers years ago but found that for best results I couldn’t find any better than using power tools, well in fact I used a wood turning lathe with a swivelling headstock, later on I used a drill with all different kinds of mops and compounds, for hard to reach areas I used cone polishing mops in flexible drill chucks and the results were amazing, I’m talking mirror finish

 

[Suns_PSD]

I use to polish my sport bike frames.

You just start with rough sand paper, go finer & finer, then move to polishing rouges. You can make them look like a mirror, unless it's a real low grade of Al.

GL.

 

[Alexbn921]

Go for the mirror polish. It will really pop and set the bike apart.

 

[Zimmerframe]

You could send it for bright dipping if you get fed up .. though I suppose this is an exercise in Covid Bordom Removal ..

Or go for something totally different and get Sublimation.

Can't be many people with a "Woody" levo for example ..

 

[2WheelsNot4]

The only difference between a highly polished metal surface and a scratched to hell metal surface is the size of the scratches. Mirror are really really tiny scratches.
3200 wet and dry will give you a mirror finsh, but you can go higher for a deeper mirror.

I've redone several retro cranks, first using a standard woodworking belt sander to take off deep scores before working through the grits. 200, 400,800 etc etc until i get to 0000 wire wool and autosol. Which results in a lovely mirror finish.
But thats half the battle, especially with alloy where no matter how shiny you make it, the surface will suffer from oxidization undoing much of your hard work. So you need to finish with some sort of lacquer.

 

[Suns_PSD]

I don't recommend coating the finished product but instead just have some basic metal polish around for a quick touch up after washing the bike.

 

[Ou812]

I don't recommend coating the finished product but instead just have some basic metal polish around for a quick touch up after washing the bike.

Anytime I’ve seen anybody try to coat polished aluminum with anything it always dulled it out. I used meguiars polish or this other stuff that I can’t remember the name of, it was a container of cotton like material. You would buff the aluminum with it and it would turn black then buff the black off and it was like a mirror again.