Retrobright Version 2 'Sunbrighting' a sample Part 2

[s8n]

hi guys , here are the photos and info that is Sunbrighting. It is the complete project/experiment from start to end , quite simply i worked on this for about a month. I got a UV Index of 1 2 and 3 but mostly 2's , also the length of time per day was around 7 hours. The Saturn Controller took 14 days , the Saturn Shell 21 days and the Dreamcast shell 20.

the 2 photos below are taken in the kitchen and the last of the 3 is taken in the lounge room under better light........

 

[FamilyGuy]

So... You just let them sit in the sun? Wouldn't that simply yellow them more?

 

[1]

So... You just let them sit in the sun? Wouldn't that simply yellow them more?

You just asked what has bugged me from the start, the logic doesn't seem to add up but from the results seen it does? it's confusing I have a few yellowed systems myself and if this works I should really try it.

 

[FamilyGuy]

You just asked what has bugged me from the start, the logic doesn't seem to add up but from the results seen it does? it's confusing I have a few yellowed systems myself and if this works I should really try it.

Be careful, it might make it worse on the long term or render the plastic very brittle.

 

[1]

Be careful, it might make it worse on the long term or render the plastic very brittle.

Yup again this is the bit that confuses me triple ? as you'd assume it would do more damage but idk I have some broken PS1's I could try this on at some stage.

 

[FamilyGuy]

Yup again this is the bit that confuses me triple ? as you'd assume it would do more damage but idk I have some broken PS1's I could try this on at some stage.

Maybe it's like that old *legend* about resurfacing CDs with toothpaste, which, IIRC, was basically a troll joke so people would ruin their CD collection.

 

[1]

Maybe it's like that old *legend* about resurfacing CDs with toothpaste, which, IIRC, was basically a troll joke so people would ruin their CD collection.

Yeah, I almost fell for that once ? being blonde sucks at times ?‍

 

[s8n]

i saw this Youtube below and thought i would try it out , and yes i just left the pieces in the sun on the decking no more no less. The thought of becoming brittle has crossed my mind but what i have done is note the date i finished the project and i will check the pieces from time to time. I think a year is a good time to call it safe , i won't be doing any more Sunbrighting till the other pieces come up good.

i would like to mention that i did try a Dreamcast Controller Port part and it helped but didn't restore it back to it's grey self , the part is still a bit yellow so it seems this is only going to work on white plastics.

 

[RunWhiteboyRun]

Maybe it's like that old *legend* about resurfacing CDs with toothpaste, which, IIRC, was basically a troll joke so people would ruin their CD collection.

Except the toothpaste trick can work. I had an Outkast ATLiens CD, a Dr. Dre CD and another CD that were scratched to shit and barely played. Using some plain ass tooth paste and all the discs would play again. Maybe with a non music CD it doesn't work.

 

[FamilyGuy]

Except the toothpaste trick can work. I had an Outkast ATLiens CD, a Dr. Dre CD and another CD that were scratched to shit and barely played. Using some plain ass tooth paste and all the discs would play again. Maybe with a non music CD it doesn't work.

There's a part of logic to it, as lots of even and small scratches are better than a few big ones overall, but it was really not the best way to go about it. Polishing with cotton pads or a baking soda dilution would've been better and just as simple.

Or, you know, find a resurfacing service near you.

 

[Anthony817]

I live in hot ass Texas, and I might just leave one of my super yellowed Dreamcast shells out in the sun. Can't hurt as it is a parts DC for if my daily driver ever goes kaput. But hey if that doesn't look good I will just paint it eventually. I figure since I am in the subtropics it should take no more than a day or so to achieve maximal results.

I saw a person in Australia do this to his Dreamcast and the results were pretty nice. I also recall 8-Bit Guy who is also from my area doing a video on this. Since it is summer time maybe I will have better results.

 

[Greg2600]

This is quite amazing. So what's the chemical explanation for why this works?

 

[Mord.Fustang]

I don't remember the 8 Bit Guy doing retrobrite with JUST the sun. This is probably the video you're referring to.

 

[FamilyGuy]

This is quite amazing. So what's the chemical explanation for why this works?

Here's the literal research paper on the subject:


The general answer to your question is at the beginning.

It seems the technique was devised to reverse the yellowing that parts acquired in the dark after initial accelerated aging.

It seems like re-exposing the plastic to the UV as a short burst can undo some of the decoloration induced by an initial exposition to UV, specifically the part that accrued in the dark, once the expedition was stopped.

I've never had any plastic yellow while stored in the dark personally, but I'm from the great white North, so maybe the plastic doesn't really age in the chill temperatures and weak sun of my home.

The only yellowed plastic I can think of is my parent's old landline phone from the 70s, and that was right in the sun for decades and is very brittle. My Model M is still grey!

 

[Anthony817]

I don't remember the 8 Bit Guy doing retrobrite with JUST the sun. This is probably the video you're referring to.

Yep that looks like the one I saw. I must be confusing for another video I seen recently.

 

[Greg2600]

Well the only explanation would be what, that just leaving it in the sun reacts with ozone in the air? Obviously the OP had great results but they took many days vs. the common hydrogen peroxide methods which work in just hours.

 

[FamilyGuy]

Well the only explanation would be what, that just leaving it in the sun reacts with ozone in the air? Obviously the OP had great results but they took many days vs. the common hydrogen peroxide methods which work in just hours.

Quoting the abstract of the paper as it's the more accurate source:

The commonly observed effect of weathered polymer samples continuing to change color in the dark was studied in some detail
for polycarbonate, styrene-acrylonitrile copolymer (SAN), and various combinations with SAN-polybutadiene rubber graft
(SRG) copolymer. All of the formulations became more yellow upon storage in the dark after accelerated weathering, and all
behaved very similarly. There was a fairly rapid shift of 1-2b units (as defined in CIELAB color space) over the first two weeks
followed by a slower, linear shift that continued for many months. This amount of color shift is enough to be visible to the eye in
side-by-side comparisons. Most of the additional color generated in the dark could be bleached by exposing the samples to sunlight
through a south-facing window. The samples usually reached the original color after 2-4 days of window exposure. Putting the
samples back in the dark caused the yellowing to start up again, although the rapid yellowing often was not as much as the first time.
Samples aged under natural conditions outdoors also underwent a small color shift upon storage for 5 months and substantial color
shifts after two years. The results are consistent with the photo-thermal equilibrium between Z-E isomers as suggested in the
literature, although some aspects remain unexplained.

tl;dr: Light and heat change the equilibrium (proportion) between some plastic isomers (same chemical formula; different structure) and that in turn changes the colour of the plastic. The plastic has to be discoloured to begin with for that to have some impact, and the restoration basically undo the part that was accrued in the dark after the initial weathering/damage. The colour restoration might not completely persists afterwards, but it might start back slower.

 

[bond.san]

+1 Sunlight;
console / computer case plastics in UK summer sunlight for roughly thirty+ days
resulted in bleaching / finished chemical aging yellowing by at least fifty percent.
BUT still gonna airbrush the plastics as UK sunlight alone is not enough too complete
the process.

 

[DeChief]

No idea how you guys are getting these results. Me, along with others I know who live in Australia, have tried this to no avail. And you know how strong the Australian sun is...

 

[s8n]

hi Chief i'm also from Oz and when i did my project it ended pretty much on Winter starting. If you've been trying during Winter that's probably part of the problem , also i was getting a UV Index of 1-2 and 3's and direct sunlight on the parts there were some overcast days in my experiment as well.