Varmint Al, and some others seem to think vibratory media brass polishers ding up and work harden case mouths.
I spend a lot of time trimming, polishing mouths. We don't need no steekin' dings.
So I wash the brass. Recipes online all over for the water / dish detergent / vinegar / salt / lemon juice mix. They're all different, and it's not "rocket fuel" -- No secret "right" mix.
Salt turns the brass pinkish. Leave it out.
Vinegar and lemon juice are both acidic. Vinegar is cheap. Skip the lemon unless there's a compelling reason you need your brass to "smell lemon fresh." I see mixes from about 1:5 to 1:1. I don't think it's crucial. Couple "glugs" in the mix works for me.
Dish detergent -- It's detergent and water. I just eyeball a "squirt" just like I do for the dishes. HOT water!
NO AMMONIA! You knew that, right?
Health concerns here --
Don't wash brass in the same gear you cook and eat out of! Get a proprietary dish pan! I found a desk organizer basket with the right size holes at a thrift shop (50 cents) that fits in the wash tub and moves the brass from wash to rinse. Cheap plastic collander works too.
Same thrift shop had a nice metal pan for laying out brass and drying in the oven, cookie sheet or bread/cake pans -- about 250 F for 20 min depending on what you have. I set the pan out in the garage to cool.
Thrift shop beats commercial "media separators" to death on price! It's not rocket science either.
No nicks, no media dust. When I'm done sizing I wash off the case lube in the dish pan too. My brass is sparkle clean, just like my dishes! NOT "lemon fresh" but that works for me.