hp 28s yellowed keys.

[Maximilian Hohmann]

Hello!

(05-30-2024 06:39 AM)Rafa Wrote:  Is there a safe way to brighten up the keys and restore them to their original tint without having to dismantle the calculator?

Maybe with ozone, but who knows what this will do with the rest of your calculator. From your picture (taken with a phone?) it is not really obviuos to me what wrong colours you see in your calculator. The purple shift key looks perfectly normal to me, the bright red ones shown in some photographs are not what the calculator really looks like!

Right now I only have an HP-28C on my desk for comparison, but its white keys are not really white either, rather something between beige and light grey. I will attach a photo of that calculator below that I took on a white sheet of paper for white-balancing in a graphics program.

Regards
Max