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Retr0Bright: Does re-yellowing occur even in the absence of UV light?

Plasma,

I have used Flat Black Dupli-Color to paint drive faces before. The results have been very good as long as you are very careful and use sparingly. However, I have noted that the plastic drive faces becomes soft under the paint and if you were to "wipe" the paint the plastic has actually dissolved a bit. Not a problem after the paint dries. Maybe it is the Dupli-Color mix - even though the can indicates it is for Vinyl and Fabrics.

Speaking of colors does anyone know how many different colors were used in the original IBM 515x/516x/517x series of equipment? I am trying to figure out if the white grill plates are the same colors across AT and XT and if it is the same color as the monitors.
 
Shadow Lord said:
However, I have noted that the plastic drive faces becomes soft under the paint and if you were to "wipe" the paint the plastic has actually dissolved a bit. Not a problem after the paint dries. Maybe it is the Dupli-Color mix - even though the can indicates it is for Vinyl and Fabrics.
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That is by design. The paint will not bond unless it "eats" the plastic surface on which you are painting. Paint that doesn't do that is the stuff you see peeling or otherwise not sticking properly.
 
Ole Juul said:
That is by design. The paint will not bond unless it "eats" the plastic surface on which you are painting. Paint that doesn't do that is the stuff you see peeling or otherwise not sticking properly.
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I though that the solvent for the paint might be part of it. The problem is that there is no second chance. You got to get it right the first time... Not something I advise on a 30 year old irreplaceable Lisa... ;)
 
I've spent the last couple of days thinking about this, as the topic was something I spent a lot of time researching into back at the beginning.

I must admit that I am dismayed and completely gutted, but not entirely surprised by this phenomenon. If you consider that the problem originates from the breakdown products of TBBP-A (Tetrabromobisphenol-A), that these breakdown products can migrate through the plastic lattice structure and that bromine is going to actively hunt for any atom that can share an electron to that the bromine's outer shell is full, then it's highly likely that migration can re-occur. You won't get 100% migration in one hit.

I did hope that the use of a clear lacquer containing a UV-blocker or up-converter might have prevented the yellowing from starting again by blocking the available oxygen that might attract the bromine, but alas this does not seem to be the case.

If the plastics masterbatchers back in the 80s and 90s had used something like Antimony Tribromide as the flame retardant this effect wouldn't have been anywhere near as bad, but TBBP-A provides more available bromine for a goven treatment level, so it may have won due to a possible cost saving at the time.

Retr0bright came about as a proof of concept that the cause of the yellowing had been identified and that (at least theoretically) the reaction was reversible. Unless you find a way to extract the available bromine that migrates to the surface of the ABS plastic, it appears that the reaction will always be reversible.

I think it would be harsh to describe Retr0bright as a total failure. As a proof of concept and demonstration of a chemistry theorem as to the cause of plastics discolouration, it was successful and magical to watch and it proved to a large extent that the effect of UV light and bromine was the root cause. It's just unfortunate that as we are dealing with a reversible reaction, it can go both ways.

At the very least, it can't be said that we didn't try hard to overcome the problem and the collaboration that it created Worldwide was awesome to watch and be a part of.


Dave (Merlin)
 
Does retrobright damage the plastic?
Does retrobright remove bromine?
Could you keep treating the plastic every few years until it no longer yellows?
 
Merlin said:
I think it would be harsh to describe Retr0bright as a total failure. As a proof of concept and demonstration of a chemistry theorem as to the cause of plastics discolouration, it was successful and magical to watch and it proved to a large extent that the effect of UV light and bromine was the root cause. It's just unfortunate that as we are dealing with a reversible reaction, it can go both ways.

At the very least, it can't be said that we didn't try hard to overcome the problem and the collaboration that it created Worldwide was awesome to watch and be a part of.
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I agree. You have no cause to feel bad about this Dave. The chemistry made sense and it was worth a shot. Retr0Bright came with no guarantees and was always an "at your own risk" procedure. One thing good about an open-source procedure is that problems and pitfalls are always discussed. It seems where ever there is oxygen, any existing bromines will continue to yellow cases. Oh well...

As to damage to plastics, that I can't answer that suffice to say that apart from the blooming effect (which is well known) my own retr0brighted (and regressed) units seem no less brittle or damaged than they were before the procedure.

Tez
 
Merlin said:
I think it would be harsh to describe Retr0bright as a total failure.
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Too right !
That would be akin to using the following flawed logic:
I have a headache. I won't take asprin, because I have found that asprin doesn't work 5% of the time. Instead, I will just suffer.
 
mnbvcxz said:
Does retrobright damage the plastic?
Does retrobright remove bromine?
Could you keep treating the plastic every few years until it no longer yellows?
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I think these are very good question and perhaps the next evolution of Retrobirght. If the tx is not harmful to the plastic (i.e. multiple applications can be used) then one should see Retrobright as maintenance regimen as opposed to a cure.

Tez,

I can't remember if you re-treated the re-yellowed pieces, but if you did: were the results as good, better, or worse then the initial treatment?
 
Shadow Lord said:
If the tx is not harmful to the plastic (i.e. multiple applications can be used) then one should see Retrobright as maintenance regimen as opposed to a cure.
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Yes, I agree.

Shadow Lord said:
Tez,

I can't remember if you re-treated the re-yellowed pieces, but if you did: were the results as good, better, or worse then the initial treatment?
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No I haven't re-treated anything yet, but probably will at some stage.

Tez
 
Failure? No way. Is furniture polish, silver polish, etc a failure because you have to do it more than once? I believe you should simply save the RetroBright for a few days before a show or exhibition, like how you'd wax your car before a show.
 
I was curious about differences in the paste vs liquid solution as well. Did anyone here do the soaking application? I guess if the bromides are in the middle of the plastic they could still come out but I'm curious if treating both sides of the plastic would make any difference.
 
billdeg said:
Failure? No way. Is furniture polish, silver polish, etc a failure because you have to do it more than once? I believe you should simply save the RetroBright for a few days before a show or exhibition, like how you'd wax your car before a show.
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I'm glad you see it that way, as this was the conclusion that the members arrived at on AmiBay after similar discussions, in that it's analogous to classic cars and getting them to concours condition before showing them off.

@ barythrin

Full immersion versus a gel coating makes no discernable difference as far as I can make out.

There was a guy in the US that came up with something he called 'Plast-Bright' about a year ago, but as far as I could make out, it was a solvent-based system and I don't think there was any way he could ship it by land post or air mail legally. Courier would have been OK, but this seemed to fade off into obacurity...
 
picking up an old thread here..
I did lot's of Retr0brighting in 2009 and 2010.
My interest for retro hardware however decreased and by February 2011 I put everything away in nice sealed boxes, stored in a dark room in my attic.
This year, I decided to go Retro again. All my treated stuff still looked brand new! I used a Commodore 128, a commodore 64C and an Amiga 500plus, each for about a month with no yellowing issues during the time of use. I then decided to use my Amiga 500 which was retr0bright treated in 2010. I took it out of the box, had a look at It (looked great) and decided that I wasn't going to use it after all and put it back in the box. Two days later I took it out of the box again as I had changed my mind and to my shocking surprise it was yellow! How could it have turned yellow in two days with the only exposure being me taking It out of the box for about 5 minutes?

The Amiga 500 was also the only hardware I treated by submerging the chassie and keys in peroxide liquid.
 
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They were treated indoors with uv light and retr0bright gel. I had another look tonight and no trace of yellowing 4 years after treatment. Im not saying that it was the method used that made the differene but it is the ony thing i could think of.
 
Haha! I live in Sweden so, no :D
To be serious, the room these parts are stored in is chilly and dark - ideal for storing retro hardware.

It could just be that having the parts soak in such a strong peroxide liquid (35%) damaged the surface allowing bromine from deeper within to re-emerge to the surface, It just needed to be fully exposed to air and normal conditions for a few minutes?

I'm currently using my C128 and 1571 diskdrive. Look at the superb condition they're still in, 4 years after retr0bright treatment.

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all the computers in the motherload have some yellowing and havent seen light in 15 years, they are not yellowed where the monitor sat on them though
 
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