A little backstory:  I got invited to a review program a while back and get various products in exchange for leaving reviews.  When I saw I could get an ultrasonic cleaner, I grabbed it.  It's fairly small in size, and the indented usage is for cleaning dental related products and hence why is has UV LEDs for sanitation.  

I decided to see how well it does at removing flux on a PCB, so I placed a small PCB with some detergent 8 and let it run.  After its 5 minute timer expired I checked it and it was far from done.  After running it again, again, and again (there's no longer runtime timers for it) it got cleaned.  

Later on I noticed something looked "off." I compared an unused PCB from the same batch with one that I put in the ultrasonic cleaner and saw a stark difference:

Yup, those UV LEDs apparently faded the soldermask.  Looks like using the little ultrasonic in this manner isn't feasible without either modifying the cleaner by cutting power to those LEDs or by using something to block out the light from them.