28 October 2011, 12:47 | #1 |
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Preventing amigas from getting yellow with time
I was talking to my friend jVIDIA and we were wondering how can we protect our amigas from becoming yellow with time.
We need to protect them from UV and several doubts came up. For example those amiga dust covers from Vesalia prevent that from happening? Are they light proof? I would like to heard opinions about this matter from the guys here. |
28 October 2011, 14:23 | #2 |
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It's quite simple. You need to seal oxygen away from the ABS plastic, as this is what is coupling to the brominated flame retardants in the plastic, making it go yellow.
It's all in here:- http://www.retr0bright.wikispaces.com Clear coating the case with a satin-finish acrylic spray lacquer should do the job perfectly. No oxygen = no yellowing.... If you can get one with a UV filter chemical in it, so much the better. |
28 October 2011, 14:54 | #3 |
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Perfect is nerdy room - no oxygen, no light...
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28 October 2011, 15:09 | #4 | |
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Quote:
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25 June 2015, 16:39 | #5 |
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So that includes the keys too right,how about painting it the same colour is was before yellowing,does anyone know the name of the colour of the A500 and A1200.(well the A1200 is white..lol)
I was just thinking of the yellowing of the ABS plastic,It happens to white gloss paint too,it goes yellow in time. |
25 June 2015, 16:47 | #6 |
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Paint it black, black is the new white
<------ |
25 June 2015, 16:49 | #7 |
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"Color #0000 please."
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25 June 2015, 17:50 | #8 | |
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Quote:
acrylic spray (clear) doesn't work ,I tested it, my A1200 end up yellowed for the 3rd time light and oxygen and cigarrete smoke : still penetrate or the yellowing process is caused by the bad plastic (degrades itself) this is my A1200 after bleaching 2 times ,the last one the spry acrylic process was included |
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26 June 2015, 08:57 | #9 |
Puttymoon inhabitant
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So: after you removed yellowing with peroxide, how long did it take the yellow plague to cover your Amiga again?
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26 June 2015, 10:24 | #10 |
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It starts yellowing immediately, but it can take from ½-2 years to become apparent again. The ones I did 2 years ago are still not as yellow as they were before I treated them. I used 3% peroxide so it was a weak solution. Although I don't have any merits to say so, it seems intuitive that the weaker solution with longer reaction time would reach a bit deeper into the plastic, making it last longer. A high concentration in a short time will only affect a very thin layer on top.
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26 June 2015, 12:17 | #11 |
Puttymoon inhabitant
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And dont you have a feeling that the plastics became fragile then? The structure of the surface remained the same?
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26 June 2015, 12:46 | #12 |
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All the things I have treated does not seem any more or less fragile. It just changed color. The texture of the surface also feels the same.
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26 June 2015, 19:53 | #13 |
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There are special cosmetics for cars to protect plastic parts against UV (and discoloration) - it should work well for Amiga also.
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26 June 2015, 21:38 | #14 |
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Sure, but then you'd have to use it when it is new and before it starts yellowing. It is too late if it has already yellowed, even if you retrobright it first.
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26 June 2015, 23:02 | #15 | |
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once the plastic is yellowed is over, you can do retrobright but the yellow plague will come faster because the plastic is weakened this is like removing oxide to a piece of metal using sulfuric acid or phosphoric acid the rust and oxide disappear fast but the oxide appears faster once you remove the piece of metal of the acid, the piece of metal end up weakened by the acid then enter in contact with oxygen,the oxide attacks faster the problem is the lame plastic the Amiga computers were done: is unstable in the normal ambient ( atmosphere) personally I do not bother anymore doing retrobright, my A1200 will remain yellowed forever |
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26 June 2015, 23:14 | #16 |
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My first A1200 (bought around 5 years ago) had a LOT of yellowing. I retrobrighted it and yellow returned after a year and a half or so, but not so much. I retrobrighted it again after another year and a half, now it has passed maybe the same time but it's only a bit yellow...
I think I will have to retrobright it from now and then, maybe only every two years or more in a near future. |
27 June 2015, 00:09 | #17 |
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I don't think that is why. The normal yellowing which takes years top happen, penetrates much deeper into the plastic since the molecules had time to move through it. When you retrobright, since it is done so fast, you only whiten a very thin top layer, and afterwards that top layer relatively quickly gets polluted again from what's underneath. Not because it is weakened.
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27 June 2015, 00:31 | #18 | |
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so according to this you must do retrobright for a month or so to make enough time the liquid penetrate deeper , so the yellowing process this tiime will be slower anyways I still think that the plastic is unstable in the atmosphere so unless you use the Amiga in the outer space it will become yellowed again |
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27 June 2015, 00:44 | #19 | |
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What I think is best is to use a weak retrobright solution to deyellow a piece, and keep doing it every year or so when it becomes too yellow again. The yellowing will be slower and slower for every time, but yes it will continue to yellow forever unless you seal it in a black box with nitrogen. If you want a one-shot solution, spray paint it, or find the moulds and cast some new ones without brominated flame retardants.. |
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28 June 2015, 16:17 | #20 | |
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As i understand main problem with yellowing of plastic is UV catalytic reaction with bromine in plastic - preventing UV to work is very important. Side to this such cosmetics create thin layer that works like fluid seal preventing plastic to react on air. Such layer can be permanent (ok semi) if painted with UV blocking transparent lacquer or temporary with some cosmetics (so from time to time you need to reapply it). See how it looks in UV light - good movie to demonstrate sunscreen lotion in action: [ Show youtube player ] |
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