Media to mirror polish Aluminum in vibratory tumbler

[hrothgar]

What kind of media can I use to get a mirror polish on aluminum in a vibratory tumbler? Also what kind of chemicals would I need (if any)?

[rarebyte]

I am new to polishing but I have had some success with alum. I used a three step process to get a mirror finish in a short time. The product was 1/4" 6061 t-6 rd alum 3" to 6" long in a rd table top vib. tumbler 50- 100 pcs at a time.

1 plastic cone media 1 hr
2 3/16" oval steel balls 2 hrs
3 walnut shells and rouge 6 hrs

I have tried substituing corn cob for walnut shells and the process totally failed.
No shine after 12-16 hours. I don.t know why the corn didn't work. I wanted to use it because the walnut plugs the 4-40 threaded holes in the ends of the rods and by experiment I discovered that corn cob does not.