Yellowing

[Anding]

Hi,

Does anyone have experience of dealing with yellowing?   Can it be cleaned up, for example with JIF or computer cleaning foam?  Or is it UV damage within the polymer matrix that's there to stay?

How come some machines are yellow and others look great for the same age?  Is it mainly sunlight?

Regards

[EnyGmaTiK]

It's there to stay I'm afraid  :cry:

And yes, sunlight it's the cause of it all  :pissed:

[AJCopland]

Thats a shame, most of my Amigas are fine but one (an A500+) i was given looks like it's spent a month soaking in custard :-D

Edited when i found this url:-
Not as bad as this at least!

[Legerdemain]

Doesn't heat also quicken the process of yellowing the plastic?

[Lando]

You just need to remove the top few molecules of plastic using a mild abrasive like iPod scratch remover.  Then it wil look good as new again.

[tonyvdb]

Unfortunatly the type of plastic used to make all the Amigas yelloed to some extent over time if it was in the sun it will be quite bad. UV rays seem to discolour the plastic the most. As stated in the above post the only option is to remove a small portion of the plastic surface and it will look like new or you can buy some Krylon plastic spray paint and repaint it.

[smiley1635]

Something like this?

[JaXanim]

@smiley1635

No, that's for polishing display screens. To recover original plastic surface, you need to buff away a few microns of the oxidised/yellowed surface using a polymer abrasive such as T-Cut. Any of the abrasives sold for cutting back car finishes should work. I suspect it will be very hard work to completely recover a yellowed case. Far easier to give it a respray job using an acrylic paint.
Cheers, JaX

[cv643d]

Someone used bleach bath to dip the Amiga shell into.

[LoadWB]

I have run into two other sources of yellowing: storage boxes and fluorescent lighting.

I had my Commodore and some Amiga stuff stored in boxes I took from the Taco Bell where I worked.  Anywhere the box touched the plastic turned VERY yellow.  I'm thinking it was an acid content issue.

Then in a room with NO direct sunlight but using a mini-fluorescent twist lamp, I watched some of my equipment yellow rather rapidly over the course of six to eight months.  Normally one would attribute the discoloration more to age, however the patterns exactly matched how light fell on the units.  So, I'm back to incandescent lamps.

[JaXanim]

It's clear that the plastic used for the A500/600/1200 cases is of low quality and deteriorates (goes yellow, and probably embrittles) when exposed to light for a sufficient period of time. Good grade plastics contain inhibitors to absorb the photons which would otherwise accelerate oxidation of the polymer. Any light will do. Sunlight (the most intense and includes lots of UV) causes the most rapid breakdown, but fluorescent and incandescent lights are quite capable given enough time. A candle would yellow an a1200 case given 20 or 30 years. It's all about the chemical reaction rate. The only way to prevent this is to keep the Amiga in total darkness but not in a cheap cardboard box it seems.

Cheers, JaX

[EDIT: The main culprit in the Amiga case is probably the pigment used to color the plastic. Cheap pigments simply change color when exposed to light. So the original buff color turns yellow.]

[recidivist]

 Darn,I was hoping for a "Magic" formula to make my Amigas look like new again.
Is there a paint brand  or cleaner that is better than the rest?
  My C64s and C128 have also yellowed. I thought it was because the former owner smoked..

[Heinz]

recidivist wrote:
 Darn,I was hoping for a "Magic" formula to make my Amigas look like new again.
Is there a paint brand  or cleaner that is better than the rest?
  My C64s and C128 have also yellowed. I thought it was because the former owner smoked..

The people at http://a1k.org/forum/
had some kind of "magic formula" for this problem.
The Photos looked pretty well.

Just ask them.

[Anding]

Idea for people in the UK .   Try JIF (plain, not lemon) on a small corner, and see how that works.  I haven't tried this myself but it used to work wonders for taking the scuffs off my motorcycle fairings when I had a scrape.  :idea:

[MigaMan]

I spray painted mine with white Krylon Fusion Spray Paint.  Dries completely in an hour and keeps the texture of the case and looks great.