How to clean the cleaner? Media tumbler.

I give my tumbler a wipe down with a damp towel after every use, so it doesn't build up. I keep two batches of media going:
#1 is 'dirty' and gets polish and all the brass straight from the range. (Gets replenished from #2)
#2 is 'clean' and gets no polish at all, I use it as almost a rinse step. (Gets replenished from a bag of new media.)

My process
Step 1: Resize brass. (Trim/chamfer/deburr or flare as necessary)
Step 2: Brass goes for a ride in media #1 for 30-90 minutes or so. Sometimes overnight if I forget!
Step 3: Pour #1 media into holding container, wipe down tumbler.
Step 4: Brass goes for a ride in media #2 for 10-15 minutes or so. (Just long enough to remove any case lube if present.)

Steps 1 and 2 are usually reversed for rifle brass, but not always.

WayWatcher,
Thanks for the tips. As for me,

1) I just tumble the brass once it accumulates to around a thousand or so, maybe every couple of days hahahaha (hardly) then tumble in walnut with polish
2) Go for a ride through the Blue 550B
3) finished case has a short trip through corn cob field.
4) shoot repeat
5) Note: wipe out tumbler between walnut grove and fields of corn

Mineral spirits and a scotchbrite scrubby pad- the green plastic kind works great, our dish sponges have this on one side. I will take the old one from the sink for cleaning the tumbler and put a new one out for the dishes. I tumble -a lot- of brass and keep 2 tumblers going pretty much 24-7 for months at a time. If you add a torn-in-half USED dryer sheet to your tumbler with your dirty brass, the dryer sheet pieces will trap the dirt and tarry gunk and can be easily thrown in the trash when you dump out your brass.

I had the same trouble with the black gunk on the brass. I think I had too many cases being tumbled at a time, and/or not enough walnut media in the bowl. Had to scrub out the bowl with scotchbrite, a real PITA. I was told by Thumler's Tumblers to run the tumbler about 2/3 full of media. Haven't had the problem since.

Also, a major part of your problems is you're using to much polish. You are depositing dirty polish and polish loaded with fine media dust onto the sides of the tumbler and in an extream case onto the cases.

When using polish, less is more or plenty depending on how you wish to put it.

Toss it out the old media, clean the inside of the tumbler, refill with new media and a TEASPOON no more of polish.

Should solve all your problems.

Use a used dryer sheet now and then to p/u dirt and dust to help extent the usefullness of your media, if needing more polish add 1/2 teaspoon.

This is just like the polish one gets when waxing their cars finish when they have balls of wax clogging up the polishing rag/cloth/towel.

Make sense?

I've taken to prewashing my brass in dish soap and water. It dries off pretty quick if you rinse with hot water. This removes a lot of the dust from the cases - dust which gets in the media and stays on your brass, no matter how shiny it looks.

Then put the still damp cases in the tumbler with normal media and a dryer sheet tacked over the center bolt of the bowl.

Windex will also soften it enough that you can wipe it out. Another way is to put a small amount of mineral spirits in the media and run it for awhile. The mineral spirits will cut the gunk and the media will carry it away. Then change the media and put in clean.

Hope this helps.

Fred