different grades of aluminum?

[horsewriter]

I am currently having a problem trying to get a mirror type high luster on a custom fender we fabricated, I have a dull haze that doesn't seem to polish out. I have had previous success on many other aluminum pieces, like my gas tank, but this rolled sheet fender just won't take that final shine.

I spent a lot of time on it, it always looks like the next pass will finish it off, but hours later, still the same haze. I tried several test methods on different sections, all to no avail, it still looks whitish next to my aluminum tank which now matches the factory chrome-like polish job on my engine parts

it started as a rolled blank, kinda like a big saucer, which was cut in half then welded into a fender. The roll marks were sanded out with 100 grit on a palm sander, then worked up through 150,220,320, 400, 600,1500.

polishing went through tripoli on a hard then medium spiral sewn, working at 90 degree pass's from each other, then to white compound on a loose section buff, passing both directions. cleaned thoughoughly between steps, and everything is seperated, even the gloves i use.

has anybody run into different aluminum grades having different levels of luster capability?
or any other ideas I can try? although the fender is smooth and shiny, it is hazy next to everything else.

Thanks,
MattD

[horsewriter]

I think I may have found the answer. I tried a test piece that was cut from the rest of the initial fender, did one 4 x 4 spot, same way, same results.

but while I was registering and typing the previous post, I douched it with a easy-off oven cleaner. a couple of quick passes under the buff, and I have a mirror spot like my tank.

I guess it had a sort of anodized surface. that somehow I hadn't broke through, even with all the sanding?

MattD

[Rasper]

Best to get your metal from a known source. I get dinged like that too sometimes, when I get cheap and use scrap yard metal. I know better, but I still do it sometimes. Works just often enough to keep me doing it.

Richard

[mpierich]

Originally Posted by horsewriter

I think I may have found the answer. I tried a test piece that was cut from the rest of the initial fender, did one 4 x 4 spot, same way, same results.

but while I was registering and typing the previous post, I douched it with a easy-off oven cleaner. a couple of quick passes under the buff, and I have a mirror spot like my tank.

I guess it had a sort of anodized surface. that somehow I hadn't broke through, even with all the sanding?

MattD

Guess it could be...if you were cleaning well between compounds (before you tried the easy-off), can't think of any other cause.

Lookin' at your nickname...do you write for "The Horse"? Just a guess...

[horsewriter]

yeah, I write simple tech articles for The Horse, actually did one on a few polishing basice when I rebuilt a wide glide for a previous project.

here's a link to the current endeavor, not fully polished yet, and I may change the frame color:
http://www.network54.com/Forum/45491...2C+tip%2C+link

I sprayed the fender down with easy-off last night, took less than a half hour to bring up an almost mirror shine on the buffer with tripoli...now I have to go back and redo the tank.

MattD

[mpierich]

Originally Posted by horsewriter

yeah, I write simple tech articles for The Horse, actually did one on a few polishing basice when I rebuilt a wide glide for a previous project.

here's a link to the current endeavor, not fully polished yet, and I may change the frame color:
http://www.network54.com/Forum/45491...2C+tip%2C+link

I sprayed the fender down with easy-off last night, took less than a half hour to bring up an almost mirror shine on the buffer with tripoli...now I have to go back and redo the tank.

MattD

Cool. That's a good mag, although I take issue with some of the guys cutting up antique frames when there are so many aftermarket choices now (perhaps you were in on that discussion...I got flamed so bad I never went back, LOL).

Actually 'twas an article in the Horse got me started polishing professionally - was one a few years ago when the fella got his tranny polished and told the price...I said "hey I can do that", and so I am...

Do you stop with the tripoli? Some of us have been using emery (I don't go past 400 or so with the sanding) then going straight to white compound. You oughta try the white after the tripoli for the finishing touch.

Good luck...bike looks good

[horsewriter]

The tripoli wokrs great, mirror shine, but leaves a sort of 'grain' in the direction of buffing. I tried the white with a loose buff, it cleared up the grain, but also hazed everything over to that normal "i need to buff it again" look.

I redid the fender with the tripoli, one pass real quick to bring up the mirror again, and now trying hand-rubbing with mothers to clean up the grain.

I also did my moon oil tank, same thing there, clear anodize on the raw material had to be chemically stripped of to get the mirror shine.

MattD

[mpierich]

Whatever works...I have a feeling that slightly different alloys need slightly different techniques.