Ah! That explains my lack of results. I soaked the
keys for five or six
hours. They got clean, but didn't change color very much. Sounds like I
pulled them out too soon. Several days, you say?
Has anyone tried a glass/plexi-glass bath w/ UV lights? It might get expensive if you want
UV lights that are dimmable (to control strength) but UV lights and ballasts are not that
expensive. A simple timer and maybe a reflective surface on the enclosure and you are good
to go. Then real experiments can be done by varying exposure time and concentration of the
solution to see if there is a happy medium. Problem is you need someone with lots of
yellowed parts that they don't mind experimenting on/ruining in the process.
-Ali