So I had my grinder out and experimented with the cotton wheels I had on the other side, attempting to compare that method with my hand-applied Mothers Polish method.

My problem is the black film left on the alloy part and the buffer wheels. It comes off the part with a little WD40, but how do I clean the cotton wheels or, better yet, prevent it from happening.

(Admittedly, I used to polish Petoskey stones, so I had some ZAM wax on the buffers, so that might have contributed to my problem.)

I used a wire brush and that seemed to clean up the pads somewhat, as well as giving me some shiny tips on the wire brush, but I'm wondering about a better strategy.

67T,
I think that the wax used was not appropriate for the speed on the grinder.....grinders typically have a higher RPM than buffers thus the wax buildup on the pad.....I would not use that pad again because there might be minute particles of grit left from using the wire brush to clean it....grit and polishing/buffing are not great for a finish.
JM2C's Ben

OK, thanks. I figured that the existing wax on the wheels was not the best idea...

So now, if I buy new cloth wheels, would I buff parts by just passing them lightly across the buffing wheels?
Is it significantly easier than using Mother's Polish?

You are always going to have some polishing compound left on your parts, but if you are getting thick globs left you are using too much compound or not enough pressure (or both). Also look into a "wheel rake" to clean your wheels if you have them gummed up.

Actually, hand polishing with Mothers, Simichrome, etc. is a good way to remove the leftover compound from machine polishing.

This is a good starting point.
Plating Kits Electroplating Kits Aluminum Anodizing Kits Gas Tank Sealer Metal Polishing And Buffing Supplies - Caswell Inc

They have a buffing guide.

How To Buff And Polish - Caswell Inc

I use a stainless steel dinner knife on the wheel while it is spinning to clean the wheel from build up. Hold it firmly with both hands on an angle.

I have an Eastwood high speed buffer and get these black marks pretty often. They clean right off with a rag when the part is still warm or with glass cleaner if the part is cool. It happens more often when:

1) I've waited too long to apply more compound (white rouge)

2) The wheel needs cleaning. Eastwood sells a nice rake for cleaning the wheel.

Buff Rake

And yes, buffing machine much more effective than Mothers on dull or oxidized parts. But beware, buffing will produce chrome-like finish where Mothers will give you a more satiny finish on an already clean part. Sometimes one more desired than the other.

Mothers also good for final step when hand sanding/polishing a part not safe to do with buffer... Think crank spider.

Have fun!

Put the Mothers polish away and buy some Blue Magic polish. I've used Mother's and it doesn't compare, not even close. And IMO wetsanding is more effective than a buffer.

As effective, maybe. More effective, please explain.

I've done my fair share of both. The buffer is certainly quicker. Do a multi-stage wet sand and hand polish on an old set of Super Champions and you're in for a 2 hour project. Buffer gets this done in <10 mins per wheel and IMO is a much better for getting in/around/under the eyelets. Hubs also no comparison with the various recesses and grooves.

i still wet sand but only on parts I don't feel I could safely use on the buffing wheel. Drive side crank arms and derailleurs are about it.

Finish wise, I think both approaches can produce the same results depending on technique. I've "over-buffed" with the machine where the edges get softened and pantos smear. I've had wet-sanding that was splotchy and uneven. Either one had more to do with my technique than the approach.