Since I'm sorting all my bricks, I discovered a lot of my original white bricks are yellowed.
There's a thread discussing de-yellowing using bleach and one using Hydrogen Peroxide.
However, for my experiment I'm using chloor (NatriumHypochloriet) with is a strong anti-oxidant.
And since yellowing of Lego is caused by oxidization (photodegradation) of the plastic, this seems like a useful experiment to do.
--> Try this at your own risk! NatriumHypochloriet is a dangerous product !!!
This experiment started today (18/11 - 4pm):
Two very yellowed wings from my old airplane will be used
One goes into the chloor, the other stays out and will be use to compare afterwards.
I'll post updates with the result.
Day 2 (after 24 hours):
I switched to another fluid after 4 hours because I was uncertain what effect the NatriumHypochloriet would have on the Lego.
I'll try again later with NatriumHypochloriet on a less important part than my airplane wings.
Now I'm using this: :-D
And here is a first result after 24 hours of de-yellowing:
This is going in the right direction!
Day 19:
This is certainly taking a long time. Here's an update after 19 days.