Tumbling cases doesn't fully clean them, why?

[Oldbloke]

500 grams hot or warm water
125 grams vinegar
1tea spoon dish washing liquid
1 heaped tea spoon salt.

Soak for about 1 or 2 hours giving a good shake in a plastic container occasionally.

Come out fairly clean, about 90% carbon removed. But no bling.

Rinse well after to remove all acid and soap.

[Mulder030]

I tried out a cap of nufinish in vibration tumbler I borrowed the other day came up good. Was mentioned on a few yank forums so tried it out.
Need to run it for half hour with the Polish and media before adding brass though or it clumps in cases I found on 1st try.

Cheers Mate, The Mrs has already brought be me home the critic acid which i am going to give a whirl. But i will definitely jot down the NuFinish for next time.