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-   -   The truth about Retr0brite – busting myths with science… (http://eab.abime.net/showthread.php?t=107519)

Jeff_Birt 03 July 2021 16:08

The truth about Retr0brite – busting myths with science…
 
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

tygre 04 July 2021 02:37

Hi Jeff and thank you!

What a cool and interesting video! Well done on the experiments and research :)

Cheers!

Damion 04 July 2021 05:04

Thanks for sharing the results of your effort and expertise, that was great!

I've been using Plexus and 210 Plastic Cleaner on my computers for ~15 years now (the latter also advertises UV inhibitors), and none of those items have yellowed. I've also had great luck with 303 in other use cases, will have to give it a shot on the computers now as well. :great

Jeff_Birt 04 July 2021 14:11

Quote:

Originally Posted by Damion (Post 1493976)
Thanks for sharing the results of your effort and expertise, that was great!

I've been using Plexus and 210 Plastic Cleaner on my computers for ~15 years now (the latter also advertises UV inhibitors), and none of those items have yellowed. I've also had great luck with 303 in other use cases, will have to give it a shot on the computers now as well. :great

One thing I should have made more clear in the video is that some plastics that have already yellowed may continue to yellow after you whiten them. Even if they are in the dark and even if you apply a UV protectant to them. This phenomenon was the subject of the paper Perifractic found and it seems it is caused by a different chemical process.

bni 04 July 2021 14:31

I also share the negative off hand reaction to sun-brighting, but what do I know.

Is sun-brighting a good option for keycaps?

And by the way, awesome video!

Nobby_UK 04 July 2021 15:12

303 'Soak in' ???

Jeff_Birt 05 July 2021 04:46

Quote:

Originally Posted by Nobby_UK (Post 1494053)
303 'Soak in' ???

Using the term more colloquially in this case, however plastic actually absorbs liquid to a limited degree. This is why you must 'dry' 3D printer filament. In an hour not much of the 303 is going to 'soak' in as happens with atmospheric moisture does to 3D printer filament but it will wet out the entire surface making sure you don't miss a spot.

Jeff_Birt 05 July 2021 04:48

Quote:

Originally Posted by bni (Post 1494044)
I also share the negative off hand reaction to sun-brighting, but what do I know.

Is sun-brighting a good option for keycaps?

And by the way, awesome video!

I think it is worth doing an experiment with the brown over white plastic keycaps that tend to splotch with Retr0Brite.

BSzili 07 July 2021 21:27

Interesting and well researched video, although maybe a bit drawn out. The main takeaways:
  1. plastic yellowing is an oxidation process
  2. retr0briting is bleaching the plastic
At first sunbrighting came as a surprise to me, but I can recall instances of direct sunlight bleaching things, I just never made the connection.

Damion 10 July 2021 21:14

Quote:

Originally Posted by Jeff_Birt (Post 1494039)
One thing I should have made more clear in the video is that some plastics that have already yellowed may continue to yellow after you whiten them. Even if they are in the dark and even if you apply a UV protectant to them. This phenomenon was the subject of the paper Perifractic found and it seems it is caused by a different chemical process.

Good point! Fortunately this doesn't seem as common, though I experienced it with a NOS 1541 (early grey type) stored in its box for about 3 months in a dark hot garage--just the top half of the case unevenly yellowed. Clearly, the heat accelerated whatever reaction was already brewing (or was prone to brew). Atari 1200XL's often yellow very slightly only at the top right side of the case, directly above a cluster of heat generating components on the motherboard.

I've been meaning to experiment with Parasol's "Varibond" product, which seems like a good permanent solution. However, it's a time suck and also expensive, not to mention a bit risky sending non-yellowed items through the post for color/sheen matching.


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