[CresentSon]

Plenty of people have posted how to polish aluminum, but I really like the satin look of brushed aluminum. I have several pieces on my build that I can get a decent look with a high rev finishing sander and 400 grit, but most pieces have too complex a surface. Any suggestions on how to get the look, while keeping it uniform, on a milieu of shapes?

I know I'm a pain, but you guys need a challenge and I'm proud to be it

 

[CresentSon]

BTW, Here's what I've got to start with...

...and what do I do, once finished, to keep it from tarnishing?

 

[66Sprint]

Well, You use wire brushes..... BUT, they work best on flat stock, the compound curves and "pockets" won't come out too well.... Small parts and curves are best when "jeweled" (a series of overlapping circular brush marks)... It's a LOT of work..... If I can get the pix up, I'll show you what I did and tell how..... (I have to upload pix, so will edit them in....) Steve

 

[NE350]

Daniel,

This is what I started with

I used the following process to get the polished look. If the piece your working on is beat up you may need to use sand paper in incriments on 600, 800, 1000, 1500, 2000 to get rid of the dents, dings after step two. The black rouge acts as a tarnish/grim remover.
1. Scotch brite wheel i.e Paint/rust/grime/tarnish remover
2. Black Rouge on Sisal wheel
3. Brown Rouge on Spiral Sewn wheel
4. White Rouge on Spiral Sewn wheel
5. Liquid white rouge
6. Maas Metal Protector

As for keeping the piece from tarnishing, with out clearcoating it, it can not be done. I used in step 6 MAAS metal protector which is a advertised as a chrome polish/tarnish preventer. It does not prevent tarnish.
This is what it looked like after the above steps.

Other pieces I polished

Hope this helps and I hope you have a lot of time on your hands,

Matt

 

[CresentSon]

I thought about buying several of the "buff pads" for my rotary tool. I have used them when making knives to get a low luster tactical finish, but they're $3 - $4 a piece and I use 4 on a standard blade. More investment than I want to spend on this effect.

I have a wood lathe that I can install buffing wheels on, so I may go with polishing but I don't particularly want a high shine. Maybe I should just break down and spray 'em with aluminum paint...

Well, You use wire brushes..... BUT, they work best on flat stock, the compound curves and "pockets" won't come out too well.... Small parts and curves are best when "jeweled" (a series of overlapping circular brush marks)... It's a LOT of work..... If I can get the pix up, I'll show you what I did and tell how..... (I have to upload pix, so will edit them in....) Steve

Hey Steve, is there a particular style of brush to use. I have several textures but there all the sort that contact to the side. Should I pick up one that produces that circular pattern?

 

[jayel]

what about blasting? with the correct media it would give it a uniform look anyway

 

[kirkn]

Good question re: blasting.

I've only done sandblasting and it's too aggressive on aluminum to leave a satiny finish. It's great to use on engine cases, cylinder and heads of air-cooled motors and wheel hubs center sections, but no good on polished or brushed surfaces.

However, I've heard different stories on using other media like glass bead or better still walnut shells.

So, I've finally picked up a case of both glass beads and crushed walnut shells for my Harbor Freight blast cabinet and I'll be doing some experimenting with my various projects.

So, Watch This Space.

 

[Bird76Mojo]

I think you'll find that the glass bead does a killer job!! It did for me. We do it at work with aluminum all the time. It leaves almost a metallic sparkle finish.

I think the walnut shell would be even better.

GB :mrgreen:

 

[Henryinva]

Walnut shell, been there, done that.
Gives you a flat matte finish, not sand paper feeling that sand blasting leaves ya with.
I'd start there right off the bat!

Henry

 

[CresentSon]

Sounds like walnut blasting is the way to go, but I don't have the equipment.
One day I'll get a rig, but in the mean time I have had some success with mt lathe and a light gauge wire wheel. It was extremely slow going because I didn't know what to expect, and because I didn't want to do any damage I couldn't repair.

Here is the first piece I did. The contours turned out OK, but in some places there is a rippling texture. At first I thought I was scoring the surface, but it seems to be an underlying texture. :?

Anyway here it is...

 

[Bird76Mojo]

The rippling effect is common on a lot of bikes. It's the casting imperfections. You can sand those off, if the part is thick enough, and if it won't cause any structural issues. Then just sand progressively finer grits until you're back at your desired finish.

I've done it to a couple pieces and they polished right up.

GB :mrgreen:

 

[CresentSon]

The rippling effect is common on a lot of bikes. It's the casting imperfections. You can sand those off, if the part is thick enough, and if it won't cause any structural issues. Then just sand progressively finer grits until you're back at your desired finish.

I've done it to a couple pieces and they polished right up.

GB :mrgreen:

I figured as much. Once I sand it out is it gone like a surface imperfection, or does it run all the way through? The reason I ask is I lightly sanded with 400 grit till smooth, but the wire brushing brought out the texture... :?

 

[Bird76Mojo]

It's hard to say what that is. Contaminates in the aluminum while melting, something cooled before something else, etc.. All you can do is try to hide it or sand off the high spots and then hide it. Maybe scotch brite pads would help here? Keep us posted on what works for you.

GB :mrgreen:

 

[crazypj]

The way my father taught me to do brushed aluminium, (he was a professional metal polisher)
you use nylon wheels similar to scotchbrite, AFTER its first been linished, brushed and mopped (polished)
You can then get 'pattern' of part (brake plates look incredible if they are 'swirled' but its real hard to get even because of casting ribs, etc) Fork legs look awful if you 'spin' them, they should be polished along length
Before scotchbrite wheels were available, you used fine emery glued to sisal wheel (or cotton mop for less cut and more flexibility) roll wheel in hot glue, roll in emery powder, roll in glue, repeat until it has layers you want followed by special fine wire stainless steel brushes (brass leaves a yellow tinge which goes black)
Scotchbrite will probably be easiest as you can get pan scourers anywhere
PJ

 

[CresentSon]

(brass leaves a yellow tinge which goes black)

Yeah, I'm learning about the "tinge". I brushed the stator cover 3 times before I realized I hadn't missed a spot... :roll:

Even a brass wheel seems to aggressive, so I'm going to polish everything using the lathe and a cotton wheel and then step down to something more coarse.

Funny, I thought brushed would be easier.

 

[CresentSon]

After long hours of experimentation, polishing, sanding, wire brushing, resanding, etc..., I have settled on a finish. The main problem was no matter what I tried I ended up with a pocked orange peel surface from the wire wheel sinking into soft spots in the surface. Sanding with 150 grit would leave a matte "brushed" look, but I couldn't get into all the concaves and cracks while keeping it uniformed.

I finally decided to work with the metal, rather than against it. I allowed the pocked surface and alternated sanding and brushing until I got a uniform matte surface that minimized the size of the "pocks". By brushing as light as possible, while still affecting the finish, I was able to keep the look even no matter what angle the travel of the wheel was in relation to the piece. This allowed me to get into the crevices.

It wasn't the finish I had in mind when I set out, but it grows on you. I can't be sure without seeing an example, but I imagine it turned out similar to the results of bead blasting. I doubt I could have gotten the same effect with a drill, I mounted my brush in a lathe at medium rpm...