hp 28s yellowed keys.

[Rafa]

(05-30-2024 08:58 PM)Maximilian Hohmann Wrote:  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!

i've looked up the hydrogen peroxide and saw a video with impressive results! probably the gel form will be less messy than the cream version, there was just the issue of applying it thoroughly and in generous amount on the surface of the plastic otherwise there is a risk of streaky result, by which i understood an inconsistent de-yellowing.
and since i can't take the keys out i'm a bit nervous about the "generous amount" of the stuff that needs to be somehow "rinsed" away afterwards and dabbing might push the stuff inside through the gaps around the keys... but yeah i could try it on a cheap old calculator first.

that disintegrating shoes must have supplied your son and his friends with some amusement : ) luckily shoes are very much replaceable!

have a nice weekend!