ok - so - zero chemists in this bunch to be sure.....
Acid removes tarnish and oxidation and, if left to soak too long, removes zinc which can leave you with color more towards copper - this means you have softer cases because the metal alloy has changed. not good - remember to take your brass out on time and rinse.
Dish soap and stuff like carb cleaner removes oil & grime and bubbles up to lift dirt off the metal - it is a base - so if you mix dish soap with your typical tarnish remover, citric acid, lemi shine, etc, you neutralize both - don't mix.
so if you have a dirty grimy batch of dark range brass - dish soap & warm water first to get as much gunk off as possible - I use a large mouth plastic bottle for this and shake vigorously - then dump & wash - then go for tarnish removal w/ SS media in a light acid solution for 2 to 3 hour tumble - less so for clean range brass.
Some pointers on tumbling wet -
Every 5th or 6th load put in dish soap or degreaser and a piece of cloth to pick up the gunk and oil residue that has built up in your tumbler along with the dirty brass and ss media - the cloth will likely come out black - pitch it. then do a short tumble with your typical weak acid to polish and shine.
When doing a detergent run, shake by hand first, then reopen the tumbler to let off some pressure from the detergent expanding, then tumble. This will reduce leaks and extend the life of your seal gasket.
Use hot water - this will cool down during the tumble and help keep the tumbler seal tight.
Make sure to take care of the rubber seal - it should be wet and clean of any debris or media when you seal it. Hand tighten so as never to crush the seal.
The #1 reason for clean brass is it is the BEST way to enable you to see any cracks or flaws in the brass, especially inside the bottom of the shell and in the clean primer pocket.
#2 is clean brass is less wear & tear on your weapon's chamber and your reloading dies. One grain of sand held on a case by a spot of case lube or bullet lube can scratch your steel. Do it enough and you'll wear more than if you'd always used cleaned brass.
And lastly - aesthetics
