Need some advice from the vintage computer community at large....

[VERAULT]

I believe it fair to say that light or UV accelerates the process.

I dont think you have the facts to say anything like that.Thats a ridiculous statement to make. And passing on the same things spit out all over the internet is just as bad. Just admit WE DONT HAVE ALL THE FACTS.

In the past year or two we have discovered Airbrighting in direct sunlight WHITENS plastic. And Anyone who has owned an old car knows how a bleaching effect cna happen to things inside thr car.

If UV exposure causes yellowing then why do all my UV lamps work so well at retrobrighting?

The only thing I can say with utmost certainty is HEAT yellows plastic. I have heat welded (hot air) some badly broken plastic and although it repaired it, at the same time it almost instantly became much more yellowed. The strangest thing was when I tried sanding some of this newly yellowed plastic The yellowing was so deep sanding wouldnt remove it.

So if you want to keep regurgitating what others say without any more understanding of the process you might as well start giving the CRT discharge disclaimer every post you make.. If you want to be a quacking duck.. might as well do it right.

 

[stepleton]

This seems like an extreme reaction --- PhilipA said "I believe", which is different to stating something as fact.

It's possible that your own utmost certainty could do with some qualification, too. For example, if "HEAT yellows plastic", then why do lots of retrobrighting procedures advise raising temperatures to accelerate the process? Note that this is the exact same question you asked about UV, just with "heat" instead of "UV".

 

[Gary C]

It's a fact that some cases suffer differential yellowing and it appears to be stark differences between parts exposed to light and parts that are not. I think we have all seen cases where the monitor has stood.

But we don't know why some do and some don't. There is a great article from an organic chemist somewhere but even they agree they don't know what's actually happening.

Too many different types of plastic I imagine to make definite statements.