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A little notice about RetroBright !

Vifa

Experienced Member
Joined
Dec 30, 2007
Messages
85
Hi,

I hate to be the guy that brings bad news, but I stumbled across something I thought I had to share with you guys.

http://aktuelbevaring.natmus.dk/afrensning-af-plast-med-retrobright.html

It is from the National Museum in Denmark, they have tested RetroBright and will not recommend it because of structural changes in the plastic. I wrote them an e-mail aksing for further information about the test they performed. Obviously, since RetroBright consist of peroxid it will make structural changes to any plastic. They will not use it to preservation since it has a non-reversible effect.


Any thoughts ?

Vifa
 
Just that I'm not sure what is new about that.
Peroxides in general work because they provide free radicals, and those break polymer bonds.

Like everything, it's a trade-off. TANSTAAFL.
 
I was always concerned about the long term effects of using it, now I know not to use it, I haven't actually read the article, but get the message.
 
And I've always been puzzled about wanting to remove the real age characteristics of something anyway. If it's yellowed, it did so on its own. Leave it. Take your meds instead.
 
As someone who has used retrobright quite a lot, I'm pretty relaxed about it too. After all, Ambient UV (and O2?) exposure over time causes structural damage anyway; plastics become not only yellowed but also brittle.

My retrobrighted machines certainly look better. It is possible to overcook the process and cause visible damage but with most of the machines I've processed the plastic looks and feels fine.

I think the the important point here is to let people know that a computer has had the retrobright treatment if you go to sell it. Then they can assess whether or not it's important to them and negotiate or bid accordlingly.

Tez
 
Well, I don't know how many of you read Danish or how well Google translate mangles the article, but this is what it says:

On ABS plastic, the Retr0Bright process is not recommended because they so far don't know about the long term effects.

On other types of plastic, like PVC, PMMA, polyetylene, polystyrene and cellulose acetate, they observed visual changes on the surface and thus can't recommend the process at all.

Basically, they're saying that a process developed to treat symptom A is not a good idea to use to treat symptom B. Like taking cough medicine against gastric ulcer.
 
I knew I would get unpopular by stating this. I started this thread to inform people about the work the National Museum of Denmark is going through to find a preservative for plastic, and found it interesting that they actually tested RetroBright, which I also have used.

As mentioned in my first post I did contact them to get further information, as ABS was not mentioned in the article as one of the test materials.

This is the answer i received from Yvonne Shashoua, who works at the project:

"Retr0bright contains peroxide and are therefore likely to react with all types of plastic also ABS. I do not recommend Retr0bright as a preservative because it alter surfaces and is therefore a non-reversible treatment."


There are two pictures in the article showing a before and after picture of the structural changes, I guess, even though old plastic gets brittle, this is not helping any further ?


Thought you guys would like to know about this before using it.
 
I do not think you are unpopular for posting about this, we appreciate your reporting the results of someone who has done the testing, even if it was in a language that most of us cannot understand:D.
Thank you.
 
The other big thing to remember is that, as a museum, they are concerned more about exact preservation, not purely physical appearance restoration. I would venture that most vintage computer collectors are concerned more about physical appearance restoration than absolute perfect preservation. (Yes, there are some, and here, probably quite a few...) Their main concern was that it "changed" the structure, not that it "harmed" the structure. (Although they also say they don't know for sure the long term "harm" potential.)

It's like the difference between "restoring" a painting and "preserving" it. A museum cares more about preserving exactly what it is, and will clean it in completely non-changing ways. An art appreciant may care more about restoring it, and so may be willing to remove trace amounts of the original paint in an effort to clean it, where the museum wouldn't.

Personally, I care more about restoration of appearance. I'm willing to trade off the non-originality and potential for longer-term damage - since these type of things are already prone to longer-term environmental damage.
 
I work in a Museum on a piece of equipment called the Hartree Differential Analyzer. If you have a browser other than IE you can see a video here:-

http://www.cs.man.ac.uk/~chl/hartree.html

What we are and are not allowed to do is vey odd. The machine was delivered to the Museum when it was about 60 years old. We have to preseve it in that state. This is a big problem it was delivered in a half restored. it was left untouched for another 15 years before anything was done. So we can't undo bodges done in the original restoration. We can replace or missing or broken bits but we have to paint these pale blue. (there was no blue on the original machine). Of course we log every change but the Museum doesn't really like restoring things. It destroys their originallity. So I can see why they don't like retrobite. It changes somthing in a non-reversible way. For many enthusiasts yellow plastic is hated, for others its part of the items history. Personally I can see both sides, but its better that painting over...
 
I knew I would get unpopular by stating this.

Not at all. Any reports on research are very welcome, especially when they relate to what a lot of people are doing. Only thing is if it's not in the "common tongue" (i.e. English) it's hard for most people to read the original source. Google translate is a kludge when it comes to these kind of things so a good translation is needed.

Tez
 
I knew I would get unpopular by stating this.
As mentioned in my first post I did contact them to get further information, as ABS was not mentioned in the article as one of the test materials.

This is the answer i received from Yvonne Shashoua, who works at the project:

" I do not recommend Retr0bright as a preservative because it alter surfaces and is therefore a non-reversible treatment."


There are two pictures in the article showing a before and after picture of the structural changes, I guess, even though old plastic gets brittle, this is not helping any further ?


Yeah, don't be getting all sensitive - you're no less popular now. ;-)
In fact, maybe you're even more popular. :D

"I do not recommend Retr0bright as a preservative"
Yvonne is obviously trying to do something that I believe most of us using Retr0Brite aren't trying to do.
When I'm using Retr0Brite, I'm trying to get the appearance back to its original state, not preserve what it looks like now.
I'll be dead and buried before some of my pieces have got back to the yellow they were.
But if someone wants to go into a museum in 100 years and see a real old yellow/brown computer then they should be able to - I just hope they have a non-yellowed brochure of what they originally looked like as well, so people don't think we were crazy making them that color.

And if the structural changes need a microscope see the differences, I'm not worried about it at all.

That was a good article to point out - it makes us realize that we're not all after the same result.
 
I think to fully be able to tell about long term effects, one needs some sort of accelerator lab in which the treated and untouched plastic can age faster. I've never used Retr0Brite myself, but have friends who have. Indeed I have a few personal cautions, but wouldn't write it off as destructive quite yet.

What I really objected about the Danish museum is when they try to apply the same process to other kinds of related materials. It sounds just as random as when people were asking Merlin etc about which other catalysators and funny stuff you can add to the H2O2, TAED and xanthan gum to get additional results. This is a result of theoretical chemestry put into practise, not a guesswork of let's mix a couple of leftover chemicals and see what we get.

It also reminds me about a computer magazine in the early 1980's who published a small machine code routine for creating white noise on the ZX Spectrum beeper. One reader posted a question whether the routine could be used for anything else than producing white noise, like it wasn't enough...
 
When we came up with Retr0bright, the inportant bit that a lot of people miss is that I spent a lot of time with some knowledgable friends who work with plastics trying to figure out why this happens. We all know the what, but there were only a few tentative stabs in the dark as to why.

We identified TBBP-A (tetrabromobisphenol A) as the most likely chemical that Commodore used in their masterbatch, as compared to other fire retardants such as Antimony Tribromide. TBBP-A degrades significantly under UV light and we believe that it is the degradation products of TBBP-A that migrate through the plastic matrix and latch onto oxygen from the air.

All the Retr0bright process does is remove the oxygen and substitute a hydrogen, if the concentration of peroxide is kept low enough or the exposure period is short enough.

If you over-expose the plastic then you do risk degrading the ABS to the peroxide and this causes the 'bloom' that people see if they overdo it.

What I'd really like to happen is for someone to take our theory as to how this happens and peer review it on a scientific basis and maybe postulate other theories as to what causes the discolouration, rather then descend into trolling the process with no rationale behind it.

As for long term effects, I have always advised using a clear-coat acrylic lacquer, to seal off the surface from the air and hopefully prevent the discolouration from occurring again. If our theory is sound as to the mechanism involved, then the plastic should not discolour again. Trying to test this with an accelerated test (for example, a Xenotest machine) may not prove anything, as this would not allow for migration effects and would almost certainly degrade the plastic by over-exposure.

All I can do is wait until another scientific mind comes along, to discuss this in more depth...
 
Well, there are some reasons based on the chemical structure of ABS why one could expect that this polymer could easier 'handle' free radicals as opposed to some of the 'other polymers' mentioned in that list where it would more quickly lead to chain scission.
But ok, I'm here for my hobby..
 
As for long term effects, I have always advised using a clear-coat acrylic lacquer, to seal off the surface from the air and hopefully prevent the discolouration from occurring again. If our theory is sound as to the mechanism involved, then the plastic should not discolour again.

I'm not at all sure that a solvent based coating would be advisable from a conservation point of view, but might nevertheless be a way to strengthen the surface and achieve what a "restorer" would like. The quoted article concludes with a concern for the apparent degradation of the integrity of the surface which they observed and that would seemingly corroborate your idea. Being more conservation than hobby or restoration oriented, my thought would be that perhaps a compromise would be to use something like renaissance wax, which is a micro-crystalline wax blend developed by the British Museum for preservation. I asked that question in the comments on the article and await a reply.
 
One of our members on Amibay came across this and it's very interesting; I'd really like to find out what he is using.


There are tests being done on the Yo Joe! toy forums with this solution and it appears that the guy is applying for a patent for it. This method also has no pedigree for how long the results last for.

When he starts selling it, I'm going to get hold of some.
 
Wow! That video reminds me of "delta" turbo battery chargers that can recharge your NiMH batteries at 1/10 of regular time. In that field, my experience is that the batteries only can take charge for a couple of times, then goes flat. I hope his de-yellowing process isn't analogue, meaning it would cause the plastic to go very brittle afterwards.
 
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