An interesting discussion... I know we've discussed some of its details before, but still worth a read:
Retrobright: The Yellow Strikes Back • deskthority (http://deskthority.net/keyboards-f2/retrobrite-the-yellow-strikes-back-t6084.html)
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The original damage from light causes degraded or free bromides throughout the case from the fire retardants. Retr0Bright only takes these away from the surface layer. However these bromides can migrate fairly freely through the polymer. They don't need light to do this. Migration is probably accelerated in hot conditions. These pre-existing bromines from the original damage migrate to the top and within a few years the surface is yellowed again. The rate of the regression depends on the inital extent of yellowing (the more yellowed, the more bromides down deep), heat exposure and the nature/quality of the plastics.
If this hypothesis is correct then a UV sealant will not protect the case. Or any sealant maybe. Unless pre-formed bromides from previous light damage can be stopped from migrating to the surface (and I don't know how you would do that) Retr0Bright is only ever going to be temporary.
Bear in mind this is just a hypothesis which fits the evidence but has not been proven. To prove or disprove it would require research. It seems a logical supposition though.
There is a long discussion about this on Amibay. However, several qualified Chemists have confirmed that it's not a hypothesis and is proven. I've been in further discussions with another Doctor of Chemistry who is looking into ways of blocking Bromine migration within the plastic, either with Chemical occupation (putting something else in the space that the Bromine would like to go), or hardening the plastics surface to make migration more difficult.
Bryce.
Ah! Anything promising?
Not yet. Or at least nothing that could be done DIY.
Bryce.
Damn, my dad was a chemist, this would've come in handy...
Changing the composition of plastic to reduce the amount of "Weichmacher" will lead to breaking of the plastic into pieces. The best thing is just: Don't put it into sunlight!
Yeah, let us hop into our time machines and tell ourselves 30 years in the past!
That kind of voyages are on sale this month, but hurry up, available only as long as supplies last!
Quote from: TFM on 18:42, 13 August 15
Changing the composition of plastic to reduce the amount of "Weichmacher" will lead to breaking of the plastic into pieces. The best thing is just: Don't put it into sunlight!
It's already been proven that it will go back yellow even if it's kept in absolute darkness. Light (or the associated heat to be exact) accelerates the process slightly but it's not the main cause. The current "research" direction isn't to reduce the plasticizer (Weichmacher), but to add additional chemicals to inhibit the Bromine migration.
Bryce.
Quote from: Bryce on 09:37, 14 August 15
It's already been proven that it will go back yellow even if it's kept in absolute darkness. Light (or the associated heat to be exact) accelerates the process slightly but it's not the main cause. The current "research" direction isn't to reduce the plasticizer (Weichmacher), but to add additional chemicals to inhibit the Bromine migration.
Bryce.
Case and point my Amiga is going yellow and it's getting no sunlight at all and covered up by deep reflective material. You cannot see through it!
Maybe it has hepatitis
Quote from: Bryce on 09:37, 14 August 15
It's already been proven that it will go back yellow even if it's kept in absolute darkness. Light (or the associated heat to be exact) accelerates the process slightly but it's not the main cause. The current "research" direction isn't to reduce the plasticizer (Weichmacher), but to add additional chemicals to inhibit the Bromine migration.
Bryce.
I was not quoting on retrobright or similar. But have you ever thought about the role the Brom plays in the plastic? I did quote about that.
Quote from: Neil79 on 13:13, 14 August 15
Case and point my Amiga is going yellow and it's getting no sunlight at all and covered up by deep reflective material. You cannot see through it!
When it was new my A1200 was on a desk where, each morning, the sun would go across it at a fairly shallow angle as it rose.
That was 20 years ago. You can see the shadows against the keys where parts of the case were never exposed. Likewise the PCMCIA port side is less yellow than the disk drive side.
Retrobrite it? Probably not. I did a test last Summer with my orange Amiga PSU case (not in use as I replaced it with a custom ATX unit) and put it in a sealed box. I want to see if it goes brittle or goes back to being orange.
There is a kickstarter campaign to make new A1200 cases so you could rehouse it if you wanted to.
Quote from: steve on 21:25, 15 August 15
There is a kickstarter campaign to make new A1200 cases so you could rehouse it if you wanted to.
Not letting one of those non original things near my A1200. A window in the top, and no Amiga logo? Yuck! These people go to all that effort and then don't bother to include an Amiga logo. Amazing.