The simplest and cheapest retrobright technique (but not the fastest)

I've seen quite a few YouTube videos about retrobrighting and most recommend using hydrogen peroxide and UV light.

But I've also seen a few where they say you can just leave the item out in direct sunlight and the yellowing will eventually disappear or at least significantly improve.

This doesn't appear to make sense... Didn't the sun cause the damage in the first place? I'm not convinced, but apparently not because people have found that plastic items can go yellow even when stored away from light. And directly light is meant to have a bleaching effect that can lighten plastics.

The other day I came across an old telephone in my collection of electronics that had suffered badly and was a dark shade of yellow instead of it's original white, so I decided to give this a go myself.

I didn't take a before picture (oops) but my first photo is of the underside of the phone, which shows its' original white colour and the yellowing around around the more exposed surfaces. Didn't I say that it wasn't sunlight that caused the problem? Then why is the underside not yellowed?



Anyway, it was a reasonably hot spring day here in Sydney with lots of sunlight, and I was able to leave the phone in direct sunlight for somewhere around 8 hours. I covered a small yellowed section with some electrical tape so that I could see what if any difference the sun made.

At the end of the day it still looked very yellow and I didn't think there was any difference until I removed the electrical tape. This showed that there was actually a huge difference!



Further updates coming soon...