I have been cleaning watches, as long as I have been collecting.
Ultrasonics loosten screws in mechanicals and their soapy, vibrating,
fluid can get through anything.
I buy a bottle of cheap liquid dish soap, Joy, at the dollar store.
The cheap ones are very simple, no scents, no abrasives, no additives.
I wet the watch under a stream of room temp water, and squeeze the
liquid directly on the watch from the bottle, Be Strong !.
Then brush every square micron of the watch with a VERY soft artists,
real bristle, brush. rinse a little and brush thoroughly !
VERY IMPORTANT !!!
1. I have never washed a watch this way that is not in good condition
Re. water resistance and at least 30m rated, No, NOT a Tissot T-Touch.
2. Rinse Thouroughly !!!!!!, for 5-10 minutes. If it is not completely rinsed ,
a slight amount of residue will remain and get into crown threads
This will brighten SS, esp. brushed, asnd give a resin G new life.
My whites stay white and my colors are still strong.
You must evaluate each watch, yourself, I have several mechanicals
that I have been washing for 40+ years, and a Gaussman for 12.
Sorry to be so long winded, I am always pleasently supprised
at how great my watches look after.
Clean up your Act !! LL