Having trouble getting great shine from aluminum

[A2Carat]

I read through the handbook from Caswell three times, and went through the posts here.

This is what I am using.
80,120,180,240,400 grit greaseless compounds
Black compound
Brown compound
High-lustre compound for aluminum.

I use a separate sprial sewn wheel (4")for each of the compounds, then a loose cotton wheel (6") for the high lustre compound.

Problem is, I went through the process and the wheel isn't as shiny as it is suppose to be. The aluminum is smooth and reflective, but the reflections in the metal are 'blurred' .. so not the mirror finish I am looking for.

I use my pneumatic die grinder and an arbor to mount the different wheels. I do get a little burning when I am using the greaseless compounds, so I should go lighter on the pressure ..

My question is, what am I doing wrong to not have the aluminum shining like a mirror? Am I missing something? Or do I need to practice?

.. I can't polish in more than one direction (polishing just the lip of a wheel) as I don't have much room to play ..

If anyone can offer my some advice, I would very much greatly appreciate it!

[mpierich]

Originally Posted by A2Carat

I read through the handbook from Caswell three times, and went through the posts here.

This is what I am using.
80,120,180,240,400 grit greaseless compounds
Black compound
Brown compound
High-lustre compound for aluminum.

I use a separate sprial sewn wheel (4")for each of the compounds, then a loose cotton wheel (6") for the high lustre compound.

Problem is, I went through the process and the wheel isn't as shiny as it is suppose to be. The aluminum is smooth and reflective, but the reflections in the metal are 'blurred' .. so not the mirror finish I am looking for.

I use my pneumatic die grinder and an arbor to mount the different wheels. I do get a little burning when I am using the greaseless compounds, so I should go lighter on the pressure ..

My question is, what am I doing wrong to not have the aluminum shining like a mirror? Am I missing something? Or do I need to practice?

.. I can't polish in more than one direction (polishing just the lip of a wheel) as I don't have much room to play ..

If anyone can offer my some advice, I would very much greatly appreciate it!

Things to try:
- Skip the 80-grit if you can - it'll just leave more scratches to clean up.
- Try going from emery (black) compound straight to white - the tripoli (brown) seems to leave a haze sometimes.
- What's your wheel speed? Die grinder seems too fast to me for 4" and 6" wheels, plus I would think it would throw off the greaseless a lot faster. I believe too-high speeds can induce haze and phantom scratches. Try going to a lower-speed drill, at least for the buffing.
- Hopefully you are using different wheels for the different buffing compounds.

[A2Carat]

Thanks for the info. I think you are right about the die grinder. I think it is spinning too fast. I will try the drill and see what happens.

You don't need too much compound on the wheels when you are cutting, right? I am using a different wheel for a different compound.. of course.

What about technique .. is there a 'pattern' to follow?

I will try the process again with lower speeds ..
Do you have any experience with the high-lustre aluminum compound? It's hard to get the compound into the loose cotton wheel.

Also, after the black, I use the brown, but when using the brown after the black, the wheel turns black .. and makes the brown compound turn black when I apply more to the wheel .. is this normal?

[mpierich]

Originally Posted by A2Carat

Thanks for the info. I think you are right about the die grinder. I think it is spinning too fast. I will try the drill and see what happens.

You don't need too much compound on the wheels when you are cutting, right? I am using a different wheel for a different compound.. of course.

What about technique .. is there a 'pattern' to follow?

I will try the process again with lower speeds ..
Do you have any experience with the high-lustre aluminum compound? It's hard to get the compound into the loose cotton wheel.

Also, after the black, I use the brown, but when using the brown after the black, the wheel turns black .. and makes the brown compound turn black when I apply more to the wheel .. is this normal?

You only need a one-second burst to apply compound to the wheels. Any more will be wasted. Rake the wheel frequently. Reapply when you see it not working any more.

No pattern I know of other than against wheel rotation to cut, with rotation to polish. When you go with rotation it'll do a better job of lifting excess compound off the surface. If you see a lot of compound sticking to the surface, apply more to the buffing wheel (contrary to what some people think).

I use regular white bar compound, don't know anything about any other.

Don't know about the wheel turning black...I assume you are cleaning the surface thoroughly between compounds. In any case rake the wheel every few minutes.

Variables are speed, pressure and heat. Try varying any of them with a given compound. It's a learning curve and seems to be different for everybody.

[jrow]

A2Carat,

Just a suggestion, you may want to try some felt buffs on a Dremel tool. They are small enough to get into the wheel lip. If you get the mandrel with them you can mount them in your drill motor, or Dremel! This should give you an opposite direction for buffing the lip. Some places, hardware stores, you can purchase mounted buffs of different diameters that will fit a Dremel or a drill motor.
Also when you clean the buffing compound off your aluminum wheel I would suggest that you use spray cans of brake cleaner then Dawn dish washing liquid. That may eliminate some of the haze you see!

John

[68commando]

A2Carat,

I too am new to this polishing. Several things you may try, polishing a wheel poses different problmes than bike castings too, you have issues getting in the lip and other tight places I don't have to deal with. I am using a rotary orbital sander I got and start out with 220 paper, the finest they make for it. That seems to get out all my old file marks and most of the imperfections of the castings. If you have a really rough casting you will have to start out with a coarser paper. Then I go right to hand sanding with 360 and at this point, I see low spots come out after the 220 scratches go away, I don't seem to be able to get out all these low spots, if I get them out in one direction, others come back while sanding in the other direction, so I leave it to just getting out the 220 marks. Then of course I go on to the 400 or 600 wet and dry. You will probably see 220 marks coming back out you missed with the 600, just go back to the 360 and get out the 220 marks, you get the gist. Then I go to 1000. I didn't get any 1200 and am not sure it would do any better, my castings are not such good material. Then I buff with black compound using an 8" wheel on an old oil burner motor I mounted an adaptor on. It doesn't have a lot of HP (1/12) but it turns plenty fast (3600) and it is not much of a job to get a shine to come right up. I use the black, brown and then the white compounds on different wheels, but to tell the truth, I don't see that the white does that much. Look at the "Sandpaper vs Greasless compounds" thread and you will see pictures of what I have done and recommendations from others that was quite helpful. You can see that I do not get a true mirror finish, but I do get a good reflection if a bit blurry, see my pictures in the other thread. I don't think it is possible to get a true mirror shine with my castings unless I plate them which I don't want to do. I have shown it to others and they are impressed, they are really impressed when I tell them it is almuminum, they think it is polished stainless right off. The work looks plenty good from 3 feet or farther away, but who is going to get up to my bike and look at it from 3 inches with a magnifying glass to see the imperfections.

If you are only going to 400 with the compounds, you may have to go to a finer grit (sandpaper) before polishing. I would try at least to 1000, try a section and see if it makes it up to your standards. See the top thread about the Motorcycle polishing 101, which is a good reference too.

Dave