A10001986 wrote:Bleaching never brings back the original color. The plastic gets rougher, some say it gets brittle. If you add temperature to support the bleaching process (as some youtube videos suggest), the plastic loses its shape, develops waves and looks awful in the end. Speaking from experience, I ruined a A1000 keyboard case that way.
To say RetroBright never brings back the original color is not entirely accurate as it most certainly can. I have used it on several Amiga, Commodore and Macintosh gear where it did work very well and the color afterward was indistinguishable from the color on the inside of the case that was original. I am thankful to have a C64c, C128 and an Amiga 500 that never ever yellowed even slightly. The C128 was sealed in the original box up until 2013 when I opened it for the first time. So I have some reference.
That said, it is not perfect and I share your opinion that there is potential for damage. Myself I have only ever used the cheap diluted 3% peroxide that you can buy anywhere and have had very good results, except for things that were darker in color like C64/VIC-20 (brown) keycaps. I have ruined a set by trying to whiten the letters.
If you don't mind the risk, you can get good results if you are patient with the very diluted peroxide. It takes way longer than the 12% or even 40% that many people use.