thouht id post this up as i read a few years ago about a solution to fix yellowing toys
well i had a go this week and these are my results
the solution is hydrogen peroxide, you need the 35% food grade stuff and can be bought off ebay
i used a transformer which i had so thought id give it ago
heres some pics of before and after
all stripped down
once at this stage give each part a clean with some soapy water and tooth brush
also you dont have to take the item completly to bits i left the arms intact
next put in a glass jar and fill with solution
this needs to be put into direct sunlight, and you will start to see air bubbles in the solution, if in direct sunlight for a couple of hours then the process will be quicker, unfortuantly for me i didnt have much sunlight so had to leave it in solution for 4 days
now just be carefull, with coloured plastic as it can be turned white, so you need to keep an eye on it, and also some softer plastics, as the softer plastics on this, mainly joints have blistered so i need to replace these, but the rest are perfectly intact, no softeness in the plastics at all, if you do different colours, use different jars i just tested it all in one jar as it was a junker