Here’s what happened Richard -
The bit of Dawn isn’t enough to clean the work. - Use something
intended for the job - there are many - my favorite is Rios sunsheen
burnishing compound liquid. Mix up a gallon so you get the
proportions correct - liquids are easy to measure. then put your shot
in a clean tumbler with clean shot. put in just enough of the
prepared liquid that you can see it just below the surface of the
shot. Run for 30 to 45 minutes - no more.
Anything longer damages the surface of your silver.
You could have put in dirty work, or have a barrel that is
deteriorating to cause the slime. Use a can of regular coke, no
bubbles, to clean the shot, barrel and work. Run for 30 to 45
minutes. Rinse and you are good to go.
If you feel it necessary (and I don’t know why) to run for a long
time, stop every hour, open the barrel, rinse, clean, add new liquid
and run for another hour.
Your silver looked dirty because you beat the dirt into the surface
of the silver. Don’t run without checking what’s happening. Check
your barrel - if it is slimy or developing scale or surface marks on
the interior - you need a new one.
And the book on Tumble Finishing Handmade Jewelry available from
Frei, Rio and Gesswein might be a good investment. Then you will have
some notion what’s going on.