On the internet a lot of information is found on retro computer collectors that use different techniques to clean their collectible and also us a technique called retro retrobright the plastic to match the original color as much as possible. Not really knowing what to expect I tried this on a small item a commodore mouse. So this is my first retrobright experiment.
This mouse color has turned to brown/yellow over time as you can see. Now I put the parts into a plastic container and added some waterstof peroxide and just water. I searched on the internet if their was a specific water / waterstofperoxide ratio but could nog found any I just experimented with a 60 percent waterstof peroxide and 60 percent water ratio and got good results. Just put it outside on a sunny day, the more sun the better. Also put it in warm water seems to do better. If you see small bubbles formed on the plastic the reaction is ongoing.
Just let it be for a number of hours and check when you think it is done. See result of this first experiment.
You can buy waterstofperoxide in small bottles at the beauty shop or… buy online for large container that is what I did. For example found on bol.com (Online shop in the Netherlands) see here