Guys -
I decap on one day and tumble on another day. So, I have the time to pre-soak the brass overnight in detergent water. This cuts tumbling time in half, for me at least, to get the results/shine I'm after. I typically use Tide detergent to pre-soak. Works great.
A friend gave me a sample of a new laundry detergent he said was even a better cleaner. Called Persil. So, I pre-soaked using the Persil. I rinsed out all the detergent water before tumbling, as best I could, at least, using multiple rinses.
However, after tumbling this batch which was pre-soaked in Persil, both the brass and pins were covered in a dark/dank surface coating. Not what I expected, and the first time this has ever happened. I had to run the brasses and pins 3 more times to remove the coating.
Even after rinsing the brass following the pre-soak, traces of the Persil must've remained. The chemicals in Persil did not agree with the Lemi-Shine and/or the auto wash and wax that I use for wet tumbling.
Just my recent experience...
Bayou52