Can't get a good polish on aluminum

[mkriegs]

I normally use these forums for anodizing but I just today had some trouble with some polishing work so I figured I'd ask in this forum.

Anyway, I'm having some trouble getting these two parts to get a good polished finish, no matter what I do there's little scratches in the finished product. The weird thing is that these are the only two parts that I've had trouble with. I've polished parts in worse starting conditions to better results in half the time. Also, I did three other polished parts in the same batch and they all came out perfect.

I used a sisal wheel with emery compound followed by spiral sewn cotton wheel with tripoli compound followed by loose cotton wheel with white rouge. I even tried the corn starch and water trick mentioned in the pamphlet that came with the 1/3 HP buffing machine kit.

The scratches aren't terribly bad and I doubt the owner will complain, but I'd still like to send these parts back in flawless condition. here's a picture:

http://i204.photobucket.com/albums/b...7/DSC00417.jpg

note - I had to get the lighting just right in order to get that picture, so they aren't that apparent in real life.

[baz]

Originally Posted by mkriegs

I normally use these forums for anodizing but I just today had some trouble with some polishing work so I figured I'd ask in this forum.

Anyway, I'm having some trouble getting these two parts to get a good polished finish, no matter what I do there's little scratches in the finished product. The weird thing is that these are the only two parts that I've had trouble with. I've polished parts in worse starting conditions to better results in half the time. Also, I did three other polished parts in the same batch and they all came out perfect.

I used a sisal wheel with emery compound followed by spiral sewn cotton wheel with tripoli compound followed by loose cotton wheel with white rouge. I even tried the corn starch and water trick mentioned in the pamphlet that came with the 1/3 HP buffing machine kit.

The scratches aren't terribly bad and I doubt the owner will complain, but I'd still like to send these parts back in flawless condition. here's a picture:

http://i204.photobucket.com/albums/b...7/DSC00417.jpg

note - I had to get the lighting just right in order to get that picture, so they aren't that apparent in real life.

if you would do your buffing in different directions like the sisal in one directio n and the spiral 45 degree from that one and the loose 90 degree as a test you would see from wich step the lines come from .
also you could have some contaminant on one of your wheels . make sure you rake them before use , if they are from the ast polishing step you cn alo try flanel buffs that are available on this site , they are about the softest wheels you can find

[mkriegs]

When I was polishing I noticed the sisal wheel was being more aggressive on these parts than usual so I think that might be the culprit. I'll try cleaning it and see if that helps.

[mkriegs]

I swapped out each wheel for a less used one and cleaned the new ones in lacquer thinner followed by soap & water followed by a wheel rake and I still got the same result. I also did that experiment baz mentioned and it seems like no wheel/compound is standing out in particular. I'm thinking that maybe doing my regular polishing followed by 2000 grit wetsanding might be worth a shot but I've never polished via high grit sand paper so I really don't know.

[mpierich]

Originally Posted by mkriegs

When I was polishing I noticed the sisal wheel was being more aggressive on these parts than usual so I think that might be the culprit. I'll try cleaning it and see if that helps.

I wouldn't use the sisal at all in this case.

You'll still have to buff after the 2000.

[jrow]

mkriegs,

On my monitor the aluminum piece you're trying to polish looks green! Is that my imagination? Are these anodized pieces?

John

[mkriegs]

yes, these pieces are being anodized after they are polished.



So, I think I'm going to skip sisal and then end with a flannel wheel and if that doesn't do it I'll just have to work something out with the customer.

Also, I only use white rouge on my loose cotton wheel yet the surface of the wheel is black, is this normal? If I remember right it turned black even when I first added white rouge to it.

[jrow]

Originally Posted by mkriegs

yes, these pieces are being anodized after they are polished.
Also, I only use white rouge on my loose cotton wheel yet the surface of the wheel is black, is this normal? If I remember right it turned black even when I first added white rouge to it.

If your using the white on loose BEFORE you anodize, yes the black is normal. The black is the aluminum you are buffing off. Rub your finger across the aluminum and see if you doesn't get black!
If your aluminum is smooth you can start with Emory on a sewn buff and work your way up to White on a loose.

John

[mpierich]

Originally Posted by mkriegs

yes, these pieces are being anodized after they are polished.



So, I think I'm going to skip sisal and then end with a flannel wheel and if that doesn't do it I'll just have to work something out with the customer.

Also, I only use white rouge on my loose cotton wheel yet the surface of the wheel is black, is this normal? If I remember right it turned black even when I first added white rouge to it.

You'll get black stuff even if you only use Flitz or Mother's by hand. You could do the same piece 24 hours a day for a year and it would still make your cloth black. It's removing a microscopic layer of aluminum.

[snoop]

stop at maximum 600wet, then go emery/sewn, white/sewn or loose, then blue/loose or canton. but before you do the last stage with the blue, go over it with some kind of very fine polish stuff. completely clean it, and then hit it with your blue. thats what worked best for me. hope that helps