hp 28s yellowed keys.

[Rafa]

(05-31-2024 06:32 AM)Bernd Grubert Wrote:  Hello,
There was an article in German on heise.de about the restoration of vintage computer housings and keyboards. It describes the reason for plastics becoming yellowish (UV-light) and compares the different methods for bleaching. Unfortunately it is behind a paywall. But if you're interested, here is the link:

https://www.heise.de/ratgeber/Aus-Gelb-w...?seite=all

Hi Bernd,

thanks for the link. from what i read elsewhere, in old plastic, a flame retardant chemical called Bromine was added to the mixture. Over time and with long exposure to UV the molecules of this chemical broke down and escaped to the surface of the plastic causing the yellow tint. some people discovered that hydrogen peroxide in 12% concentration found in a cosmetic product can de-yellow the plastic by applying hydrogen peroxide onto the plastic and, ironically, exposing it to sun light for a day or two!

i'm not sure if that's the same method the german article describe. i will see if it's worth paying to read it.

thanks for the tip.