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The truth about Retr0brite – busting myths with science…

These are small spray cans, only 150g, but for some colors it is available in the standard size

One great thing about this paint is that there are multiple shades of cream to white just in that color spectrum, each has a specific ID number, the slightly off white color in the photo is DSTH01, the one I used for the Apple computer and my IBM5153 monitors was called "Arctic White" (cannot remember the number) but there is a similar one Alaskan White, number DSF63. A cream (Off white) color is Torquay Sand, number DSH47.

The early cans of this, available in AU were called "Holts" Dupli-color, like the photo of the can with the red top, later they were just called Dupli-Color. It says on the tin of the white one (a current product) manufactured in AU by MMP Industrial, under license from the Sherwin Williams Company, Cleveland Ohio USA.
 

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Hugo Holden said:
I'm not sure all the myths were busted with Science in the video. All good experiments have controls, and for this problem it would require much longer time frame testing and more input from materials Engineers, though specifically it would require before and after high magnification both light and Electron Microscopy of the treated surfaces. And then as mentioned the force tests for any change to how brittle the plastic is.

I would not claim to be an expert in the effects of oxidation & bleaching on plastics (either by chemical or photon treatments) but there is one thing I am fairly confident about; these are both damaging processes to a surface and they break chemical bonds, possibly creating microscopic pits, crevices & cracks. The net effect for some plastics where it is optically visible (not necessarily ABS) but certainly Acrylic, is to start microscopic cracks which can later with force lead to fracture of the material. Most people are familiar with the glistenings that appear in clear acrylic panels after chronic sunlight exposure and in this case they appear within the material as well as on the surface. Clearly the molecular bonds are breaking. Sunlight turns Nylon to powder.
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I did point out the limitations of my methods in the video. The experiments were constructed in such a way that they could be duplicated by anyone without any expensive laboratory equipment, i.e. make the methodology approachable by anyone.

Obviously the oxidation from UV exposure inflicts some damage on the plastic, as does the Retr0Brite process. The question then is not 'if' but 'how much' and is it significant w.r.t. all the other wear and tear something goes through in its life. My grandfather used to joke that some people would wear out the paint on their car by washing it so much. Washing your car does scratch the clearcoat ever so slightly but it is insignificant w.r.t. the wear and tear the paint goes though in average use. The process of polishing something is in fact inflicting many thousands of minute scratches in the surface but the result is that it looks nicer and the 'damage' caused by the polishing process is insignificant'. I would argue that using my vintage computer gear does more harm to the surface finish than Retr0Brite.

Plastics are all different, as you point out some clear plastics will get cloudy and crazed by wiping them with something as simple as alcohol while other types are unaffected. Acetone is very damaging to some plastics yet not others. The PLA key rack I used was damaged by the Hydrogen Peroxide but the polypropylene tub it was in was not. We can't really generalize such that we conclude what is damaging to one plastic is damaging to all. (In retrospect I should have known the PLA would work as last summer we were printing facemasks for the local hospital and the challenge they were having was to find a way to sterilize them with out damage and they found H2O2 was not suitable.)
 
Caluser2000 said:
I have had ABS computer case a components go yellow without any exposure to the sun stored in my garage and covered with a heavy blanket.
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The paper I reference in the video which was found by Perifractic a few years ago is about this phenonium. It seems that the initial exposure to UV can cause some types of plastic to become a bit photo/temperature reactive. They found that even plastic samples wrapped in foil and stored at -10C would continue to yellow and that bringing them out into the light would reverse the yellowing. Quite and interesting phenonium that has been observed by many over the years.
 
Is it not a fact that 'bromine', which is a flame retardant, is the principle cause of 'yellowing' in plastics when exposed to UV light. The molecules in bromine breakdown and leech to the surface cause the yellowing effect. According to sources, modern plastics do not use bromine as it was prevalent in the 80's. Thought I'd ad my 2¢.
 
If it was bromine that caused yellowing it would be able to be washed off as its water soluable. I know it's water-soluble because we used it in our desalination equipment so we can drink sea water when away on deployment.
 
VERAULT said:
If it was bromine that caused yellowing it would be able to be washed off as its water soluable. I know it's water-soluble because we used it in our desalination equipment so we can drink sea water when away on deployment.
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I don't know much about the makeup of the plastics, but from what I understand, is that the bromine was intrinsically added to the plastics upon formulation and was not simply sprayed or painted on. So, I don't think to you can simply wash or wipe it off.
 
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Again, I'd want an explanation why two pieces of identically colored plastic on a system can exhibit yellowing differences, even when adjacent to one another.

No, we're a long way from "truth"--and that word in today is particularly loaded, what with fake cures and protocols being shamelessly promoted by people in the public eye--who have no business doing so. How about the "truth" of hydroxychloroquine or Ivermectin as a cure? Various governments have bet the house on those with disastrous effect. How many needless deaths have occurred because someone claimed to have the "truth"?

We don't know the TRUTH about the causes and the retrobright "remedy". All we've got is some anecdotal evidence.

Show me mass spectrograms, photomicrographs, detailed chemistry and I think that we'll be closer to the "truth".

Until then, we're just messing around with the Phlogiston theory.

I commend Jeff for his hard work and diligent efforts, but I don't think we've got the "truth" yet.
 
Thanks for the pictures of the paint, Hugo.

Yup, that Duplicolor logo is the same as the one sold by Sherwin Williams in the US. I guess they must be largely the same.



I also think that more investigation needs to be done. The biggest issue, as Jeff pointed out, is that the exact mixtures of plastics and chemicals in each ABS mix are different. They add things like flame retardants and temperature stabilizers to plastics in order to keep them from breaking down into monomers or crumbling to powders. What additives were used is going to play a potentially huge role in the effect of hydrogen peroxide. So there is no one "Truth" about retrobrighting. It's a CASE by CASE scenario. (lol)
 
VERAULT said:
If it was bromine that caused yellowing it would be able to be washed off as its water soluable. I know it's water-soluble because we used it in our desalination equipment so we can drink sea water when away on deployment.
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Lots of things are water soluable until you mix them with plastic pellets and then melt them in an injection molding machine.

Bromine is used for killing bacteria in water and is generally used in a polymer form to slowly dissolve in water (100% liquid bromine is very bad for you and your skin).
 
Unknown_K said:
Lots of things are water soluable until you mix them with plastic pellets and then melt them in an injection molding machine.

Bromine is used for killing bacteria in water and is generally used in a polymer form to slowly dissolve in water (100% liquid bromine is very bad for you and your skin).
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Bromine is/was used as a fire retardant in plastics back in the 80's. It contributes to the discoloration when it breaks down.
 
Chuck(G) said:
If the yellowing were due to free Br ions, wouldn't treating the piece with a strong base, such as NaOH de-yellow the plastic?
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Some plastics don't like NaOH. Besides if free bromine is the issue then you will get those breaking off again over time since they are in the plastics.
 
The point is that there are other substances that readily combine with bromine (e.g. NH₄OH). My query is that if it's the free bromine that's causing yellowing, that a strong base should result in de-yellowing. I don't think that would work, just from a gut feeling.
 
If the free bromine is causing oxidation (this is why it’s good for water purification), wiping off the bromine with water or treating with something that reacts with the bromine won’t reverse the yellowing (removing a catalyst doesn’t undo the reaction). You’d still need some kind of bleaching action as indicated in Jeff’s video. Point is that the yellowing could be from the action of the bromine without negating the need for a bleaching action to reverse it.
 
I'll add that when the retrobright thing came out, I experimented with other reagents to see if the yellowing could be reversed without the bleaching effect. A couple that I tried were sodium bisulfite (Na₂SO₃) and oxalic acid (C₂H₂O₄); both are used as mild bleaches, mostly for rust stains and the like. Bupkus, as far as I could determine.

This got me wondering if the effect was due to the dye, more than the ABS itself.

Unpigmented ABS is slightly yellow:

Plastic-ABS-Grains-300x267.jpg


Do other ABS/Dye combinations yellow? For example does a red case yellow to orange? It would be hard to tell if a black case yellowed, but a blue case might go green. It seems that the yellowing effect is confined to the light shades of buff or beige or gray (which has a certain amount of white pigment in it).

You see where I'm going here, right?
 
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vol.2 said:
According to Birt's video, the Bromine thing is a myth, and it's actually the result of flame retardants that are often mixed into the bromine added to the plastics. https://www.youtube.com/watch?v=YPl356YKcVs&t=615s
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He certainly made that assertion but, at least in my view, did not provide any evidence of that. I think his conclusion about bleaching is valid, but as I said, it does not preclude (at least one of) the catalyst being the added bromine.
 
p.s. there are academic papers that talk about the accelerating oxidation effect of bromine on plastics it is added to
 
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