Autobot032 wrote:HP might be great for the here and now, but we have no idea what the long term effects are. It's literally changing the chemical makeup of the plastics to create that recoloring effect. Same with dye, but it's not nearly as harsh as HP. Though you have to be careful not to get the water too hot, otherwise you'll warp the plastic.
Well... It's not as if sunlight had such a great effect on the plastic. Let's be honest, HP is almost always only used on those toys (out of box) whose display (and monetary) value has already gone down significantly due to the discoloration. Even if, in a couple of years time, it might turn out that HP has a brittling effect on all plastics comparable to GPS, I do believe that restoring those toys by using HP is doing them a favor, even if it's only for a couple of extra years.
The most useful AND scientific stuff I have been able to find regarding the use of HP is on this site.
Anyhow, seeing as UV damage doesn't actually seem to be the problem of the topic starter, it might be time to get back on topic...