Ok, like the noob that I am, I damaged a perfectly good set of white-on-black ABS keycaps
Here's the story (sorry its long), but it may be of benefit to some.
I bought this filthy POS keyboard for the caps (ABS white-on-black), and proceeded to remove the caps and throw them into my ultrasonic cleaner.
Not knowing anything about how to clean keycaps, I added a little chemical cleaner (had bleach in it) to the water and turned the ultrasonic on.
10 minutes later, I pulled the keycaps out and rinsed them off - yay all the grime was gone, but after letting them dry, I found that they were now slightly grey (not the original shiny black) - ARGH!!!
I do 3d printing as a hobby and print only ABS - I have a modified rice cooker used for Acetone vapor washing my parts (makes the parts smooth and shiny).
I figured what the hell, the caps are trashed anyway - might as well try it.
I proceeded to put the caps thru an acetone vapor bath - grey tone is gone, back to nice shiny black.
The keycaps no longer have any UV protection coating on them, but since they're black, i'm not concerned.
After doing that, I tried a batch of terribly UV damaged (I think PBT) keycaps that I retrobright'd, then cleaned in the same manner, and it worked for them too - still working on getting them less-UV damaged, but that's another story.
I found that an easier (and safer) method to acetone wash the keycaps is to put them legend-up on a sheet of cardboard, then line a metal baking pan with paper towels (use magnets to hold the paper towels to the inside of the baking pan), soak the paper towels with acetone, and cover the cardboard (with all the keycaps on it) with the baking pan (acetone soaked papertowels down - don't let them touch the keycaps!!!). Wait about 45 minutes and remove the baking pan.
Let the keycaps air-dry for about an hour (can be touched in about 15 minutes ~ sooner will leave fingerprints on them)
Acetone vapor is heavier than air and will sit on top of the keycaps softening/smoothing the surface.
I didn't have have any issues with legends melting off or getting distorted.
You should try this on a test batch before using on a much-loved batch of keycaps. (disclaimer #1)
Acetone (including vapor) is flamable, so do this outside away from flame sources. (disclaimer #2)
If your keycaps were textured before, they will most likely be less-textured due to the smoothing process (disclaimer #3)
Paul (HB)
Location - California