Theres a polish called MAAS and works real good to polish different
metals ,I have polished aluminum with it and it works great and it even
works on other metals as well including tarnished brass ,I have polished
a brass kick pad on a door that was black and after I got done it shined
like a mirror ,you can find it in automotive sores and in the cleaner
section in walmarts around tarnex ,you can use paper towels to use it
but I find white cotton rags works best ,you just keep rubbing it in til
it turns black and keep going till it completely disappears .
The buffing wheels, speed, and technique are more important than the
compound used. Mothers polish reminds me of Brasso, and I never had good
luck with it because it loads the wheels and leaves black residue. I
usually cut aluminum with tripoli and finish with white rouge. Unless
you're going to do a lot of this type of work or just want to learn, let
a pro do it for you.
I wouldn't have envisioned the OP would use a buffing wheel on a 1½x2' plate.
Sure, that would turn a buffing wheel black. Mother's is not a product to be
used with a buffing wheel at all, rather it, like Brasso (which works just
great, I use it every 3-4 weeks on my brass belt buckles) is designed to be used
with a rag and your Armstrong polishing machine.