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The truth about Retr0brite – busting myths with science…

Jeff_Birt

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Joined
Jun 14, 2016
Messages
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Location
Rolla, MO
The truth about Retr0brite – busting myths with science…

One of the situations we are often faced with when restoring an old computer is a yellowed plastic case. You have probably heard of Retr0Brite, few things in the retro community have caused as much controversy, rampant speculation and unfounded opinions as this subject. While there has been a lot of speculation and theories passionately bandied about on this subject there has not been an effort to understand the process.

A combination of research and practical experimentation was done to try and answer the questions: What it is Retr0Brite doing and what is it doing, or not doing, to the plastic. We will discover where color comes from, what plastic is, what makes plastic yellow, and what Retr0Brite is actually doing. This video is the result of an effort to get to the bottom of the matter using a scientific approach.

I ask that you please keep an open mind and watch through to the end of the video before banging out a comment on your keyboard.

https://youtu.be/YPl356YKcVs
 
Ill give it a watch.. and Dont worry. I never leave comments.... ever..

This is the place I leave comments.
 
Ill give it a watch.. and Dont worry. I never leave comments.... ever..

This is the place I leave comments.

I love comments! Since there was a lot of technical information presented I was hoping that folks would listen to the whole presentation, get all the facts so to speak, before commenting.
 
Good video. Very informative and it puts alot of myths to rest. Like so many things. False truths get passed around by word of mouth. Enough people do it, and it becomes "truth".

The only bits I can add is I tried pure sodium percarbonate, it essentially turned the water to bleach and the end result was not to desirable. Not to mention the PH change where it is highly corrosive. I will stick to the plastic wrap, 40 or 50 % cream suspended peroxide in my UV lamp chambers. Works great and leagues better than the marbling I was getting using the Sun. Not to mention I can do it in the winter.
 
Hey Birt,

Thanks for putting together all that great info, and doing those experiments. It's a great contribution to the hobby!

One thing I would say is that I was most interested in the "makes plastic brittle" myth, and I felt like that part of the video wasn't really backed up by any experimentation. I would be interested to see how much the peroxide versus the sunlight versus the UV lights actually makes a plastic part brittle.

It wouldn't be too hard to setup. One wouldn't even need it to be yellow for the experiment, just a new sheet of ABS, cut into strips. Use a tensile strength rig (should be some stuff at the University), and get a baseline, then douse a bunch of different strips in liquids and light to see how it changes them. Maybe also an old piece of random ABS from a cheapo thrift store item would be good as well.
 
I think its the UV that makes the plastic brittle (or just their decomposition from age depending on the polymers involved). I have used UV C lights on plastic and it destroyed them.
 
You know, I dont know if you guys heard this.. Bug Eggs may be bad for you.. Thats what I heard anyway....

Who or what is Ole?
 
Hmm, cant recall posts from him since I really started using this site. I like his website and his town/village looks like a nice place. Was he into retro computers?
 
I remember him here on the forums and from work. We did business briefly.
He's my neck of the woods. Perhaps I should make a day trip and head his direction. ;)
 
Good video. Very informative and it puts alot of myths to rest. Like so many things. False truths get passed around by word of mouth. Enough people do it, and it becomes "truth".

The only bits I can add is I tried pure sodium percarbonate, it essentially turned the water to bleach and the end result was not to desirable. Not to mention the PH change where it is highly corrosive. I will stick to the plastic wrap, 40 or 50 % cream suspended peroxide in my UV lamp chambers. Works great and leagues better than the marbling I was getting using the Sun. Not to mention I can do it in the winter.

Sodium percarbonate when mixed with water makes hydrogen peroxide and the soda ash settles out. As pointed out in the video the PH value is 11, very alkaline. Corrosion could be an issue but I did not experience a problem with it in my limited test. You have to be careful and mix it in the right proportions to the concentration of H2O2 you are after.
 
Hey Birt,

Thanks for putting together all that great info, and doing those experiments. It's a great contribution to the hobby!

One thing I would say is that I was most interested in the "makes plastic brittle" myth, and I felt like that part of the video wasn't really backed up by any experimentation. I would be interested to see how much the peroxide versus the sunlight versus the UV lights actually makes a plastic part brittle.

It wouldn't be too hard to setup. One wouldn't even need it to be yellow for the experiment, just a new sheet of ABS, cut into strips. Use a tensile strength rig (should be some stuff at the University), and get a baseline, then douse a bunch of different strips in liquids and light to see how it changes them. Maybe also an old piece of random ABS from a cheapo thrift store item would be good as well.

That is a much more complicated experiment as it would require months in a light chamber to artificially age the plastic, Then some of it could be treated and you could compare the original to the yellowed to the treated. I'm not sure that you would see much of a difference on a tensile testing machine unless the plastic was severely damaged.
 
Another great contribution from Jeff Birt!

In the topic of "makes the plastic brittle" I can perhaps add a few facts. As a longtime amateur radio operator, I have always had lots of stuff on the roof, exposed to sunlight, rain, saltwater spray (I live at a few hundreds meters from the sea) and in general whatever lives in this planet's atmosphere.
Plastic stuff on the roof are usually antenna connector covers, antenna elements insulators, boxes I use to route cables or protect preamplifiers, antenna "domes", etc.
Sometimes, these plastic parts are partially covered with insulating tape or ties. After years on the roof, almost all kind of plastic gets brittle or turns into a dusty useless material, including nylon
parts. Possibly the only exception seems to be teflon, but I haven't left enough of it to make a real scientific experiment about that.
What's interesting is the plastic parts covered with insulating tape or other opaque parts, show usually no decay and no "yellowing". They remain almost as strong as they were originally.
My educated guess is that the plastic degradation is due to UV exposure.

Frank IZ8DWF
 
This jives generally with what I would assume. I've also seen antennae parts on a roof break down, and I assume UV is an issue. I suppose from that, I would say that the UV part of the process can indeed harm the plastic, and could be an issue if it is already substantially damaged.

So if UV is involved in the retrobrighting process, then it is making plastic brittle, and that's not actually a myth. I suppose from the video, it's not necessary and you can just use heat and chemicals with no lights.
 
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