hp 28s yellowed keys.

[Maximilian Hohmann]

Hello,

(05-30-2024 06:31 PM)Rafa Wrote:  i definitely am not so bothered that i'd try some risky chemical sorcery. I thought that if this was an easy rub with something that one can buy in Rossmann and does not seep into the electronics then i might consider it.

The only substance that comes to mind, apart from ozone which I already mentioned (*), is hydrogen peroxide cream oxydant. Rossmann probably does not have it, but you can mail order it from Amazon. I have seen it recommended for whitening computer keyboards that have turned yellow over time. It is a gel that can be applied to the keys with a cotton swab and which won't seep into the calculator. But you might want to try it out with another, possibly non-functioning, calculator first!

Regards
Max

(*) Applying ozone is not as scary as it sounds. I have been using a little ozone generator since years for variuos purposes. They can be found on eBay/Aliexpress for very little money but the cheap ones are probably not compliant with European standards regarding electrical safety. Put it in a plastic box together with the object you want to treat, place it somewhere outside of your appartment (ozone is good for the stratosphere but not for our lungs) and let it run for some minutes. The only thing I ever ruined with ozone was a pair of sport shoes of my son. They were not as white any more as he wanted them to be. The ozone restored the colour, but the plastic or rubber of the sole turned so brittle that it broke into pieces when he tried to put them on.