Black streaks, scratchs & Haze...

[bling88]

My latest project was to polish a set of aluminum wheels.. (first attempt)After the wheel was all sanded up to 400 grid. I started polishing with the Black/6" Spiral sawn buff wheel, then brown/6" Spiral sawn and then white/6" loose sewn wheel.

The polishing was going good before the white, as I notice the haze after the white. So I went back to the brown, cause it was actually clearer (less haze). then the black streaks started to form. (see pic below) it actually marks up and scratches the aluminum. I have raked the buff wheel and redressed it and tried it again, and it was only fine for a short while then the black streak started to form again.

I'm looking for a mirror like shine without the haze and streak marks. but its doesn't look too good right now.


Any tips or suggestions will be appreciated.

[bling88]

Here's the pic of the haze... Its much more noticeble in direct sunlight.

[jrow]

bling88,

Looks like a T-Bird wheel! 88?

To me it seems that you still have scratches left from the 400 grit sandpaper! You also may have some PITS in the wheel that your buffing wheel is catching on causing the streaks! Some of the pits you can sand out others you can't, just the nature of cast aluminum!
I would try wet sanding a portion of the wheel with some 800 grit sand paper, then try re-polishing that area and see how that works. You need to remove all the scratch marks from the 400 grit sanding. When you use the white, make sure that you just barely touch it to your buffing wheel. The temperature of the aluminum your polishing has a lot to do with the shine that you get. Polish in different directions also, instead of polishing across the spoke, polish with the spoke, and alternate. Clean the aluminum wheel with brake cleaner or acetone after each polishing compound that you use. Also rake your buffing wheel often. Don't use the same buffing wheel for different buffing compounds.

John

[bling88]

^ actually you're half right..... the wheels are off of a 93-95 T-bird SC, and the centercap is from a 88 Turbocoupe.

Thanks for the advice. looks like I'm going to have to redo the wheel again..... About the temperature, would you say around 65-70 degree is too cold?

Would you know why some people are using the green and blue. I thought the green is for stainless steel, and blue is for plastic.

BTW: I'm using a 3/8 6.5amp drill for the polishing with max speed of 2500rpm. Is that not fast enough for the 6" loose sawn wheel?


Joe

[pickleboy]

Originally Posted by bling88

BTW: I'm using a 3/8 6.5amp drill for the polishing with max speed of 2500rpm. Is that not fast enough for the 6" loose sawn wheel?


Joe

that give about 3750 sfm and you should be closer to 6000 for ideal polishing

[Rasper]

I have found it best, if at all possible, to use bench mounted polishing wheels: they are cheap and simple, and you have much greater control, but holding a wheel up to one of those may be asking too much. For portable work I buy cheap, (throw away), sanders/polishers. $15 max. I attach my polishing buffs however I can and go at it. My favorite is a Black and Decker polisher I bought on e bay. I'm talking cheap. Home handyman stuff. It's weighs almost nothing and turns about 3500 rpm. It's so cheap, instead of a threaded shaft, it has a threaded hole in the end of the shaft for a #12 machine screw, and it's so worn out the bearings squeal like crazy whenever I start it up. Keeps polishing though. I'm looking for another one just like it.

Aluminum is a bit difficult sometimes. I guess it's because it's so soft. I find I have to experiment a little and just find what works.

The most important thing in polishing is: you absolutely have to completely sand out the scratches left by your previous grit of sandpaper. The 240 has to sand out all of the 120 grit scratches; the 400 has to sand out all of the 240 grit scratches, or you will not have a flawless finish. It would make you ill to hear about all of the times I have had to go back and sand my jobs all over again because I didn't. It's hard to make yourself do it; (it's hard work), but it always gets you if you don't.

Richard

[jimcarry]

Originally Posted by bling88

^ actually you're half right..... the wheels are off of a 93-95 T-bird SC, and the centercap is from a 88 Turbocoupe.

Thanks for the advice. looks like I'm going to have to redo the wheel again..... About the temperature, would you say around 65-70 degree is too cold?

Would you know why some people are using the green and blue. I thought the green is for stainless steel, and blue is for plastic.

BTW: I'm using a 3/8 6.5amp drill for the polishing with max speed of 2500rpm. Is that not fast enough for the 6" loose sawn wheel?


Joe

Jrow has given some excellent advise here the reason for the different compounds is that each compound has different cutting power on most items I start with black this is the most abrasive
and will leave its own scratches then brown which will remove the scratches from the black but again will leave its own then white to remove the scratches from the brown then blue the different directions are explained very well in the Caswells polishing book here http://www.caswellplating.com/buffs/buffman.htm

[jrow]

Originally Posted by bling88. :smile:

About the temperature, would you say around 65-70 degree is too cold?
Joe

When I talked about temperature, I was talking about the temperature that is generated during the buffing process of the metal that you are buffing. If it gets to hot it will leave brown burn marks on the Aluminum, if the temperature is just right it will leave the shine that you want. Not a big consideration but something that you should be aware of!

John

[bling88]

Originally Posted by pickleboy

that give about 3750 sfm and you should be closer to 6000 for ideal polishing

How about going with a 8" wheel? I know they don't recommend it.. but it is only for finishing, and it'll be the loose sawn type only.

[bling88]

Originally Posted by Rasper

For portable work I buy cheap, (throw away), sanders/polishers. $15 max. I attach my polishing buffs however I can and go at it. My favorite is a Black and Decker polisher I bought on e bay.

Would you know what model of the B&D sander is? All the cheap sander I have seen spins at 10.000rpm. and the ones that has variable speed are not cheap.


Joe