I've recently done quite a bit of retrobrighting using only the Salon 40 vol 12% creme solution. Some of us might remember the old Castrol GTX ads from years ago,
"Oils ain't Oils". When it comes to retrobrighting "Plastics ain't plastics".
For the most part My retrobrighting has been successful. Amongst the successes are my Amiga 500, Vic 20 case, Front of my 486 AT case, also my beige AT keyboard.
All those have now got a mostly even whitening and look really good.
What didn't work well was that I tried this on my Vic-20 keyboard that has the PET Style keys and it has wrecked them by turning them a lot grayer. The same happened
to the top of my c64 keyboard. Also my Beige ATX case from 2000 has got a streaked look now. I think if the plastic is more porous this doesn't work very well.
The best bit of advice might be to NEVER try this on keyboard keys that aren't beige or white coloured. Also only leave some items in the Sun a few hours. In Brisbane here
the Winter sun is powerful enough, in the Summer the plastic will likely melt.
The writing on the top of the keys was yellowed which was why I tried it. The good news though is that I have found Creme Cleanser will get the colour back, but it's a lot of hard work
and it is very hard to keep the printing that is on the front of the keys, although I can redo that with a White on clear printing cartridge and a Brother label printer.
The N and M keys have new petscii characters on the front from a brother label printer.
Atari 2600, TI994a, Vic20, c64, ZX Spectrum 128, Amstrad CPC464, Atari 65XE, Commodore Plus/4, Amiga 500
PC's from XT 8088, 486, Pentium MMX, K6, Athlon, P3, P4, 775, to current Ryzen 5600x.