Retr0bright - a cautionary tale

[XMIT]

Retr0bright (retrobright) is an oxidizing treatement designed to reverse bromine yellowing in ABS plastics. For more information see http://www.retr0bright.com/ .

This week I used Retr0bright successfully to remove yellowing from a keyboard case. However, Retr0bright *will* lighten some black dyes and therefore must be used carefully! I managed to ruin some very nice double shot keys.

I started with this beautiful keyboard:

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It is, I think, a Sperry Univac F39W-00? As you can clearly see the outside of the case is very yellow compared to the inside:

DSC_3466.jpg (209.95 KiB) Viewed 19699 times

So retr0bright to the rescue! My first attempt differed from the "official" recommendation in several ways:
- peroxide strength: I only had 3-5%, when 10%+ is recommended;
- UV strength: I did this on a cloudy day;
- temperature: I left the setup outside where it was 3 C. Room temperature (20-25 C) is recommended.

I also decided to Retr0bright the key caps to pull yellowing out of the legends. In retrospect I should have tried the entire process on *one* key before proceeding. Though, even this would not have saved me necessarily, as there were different plastics used on the same keys.

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This attempt was not successful. The case got a tiny bit lighter, but it was barely noticeable.

So I made some process improvements to better align with the Retr0bright website's recommendations:
- peroxide strength: 10%, using a "volume 40 clear developer" from the local beauty supply;
- UV strength: I purchased a 20W UV bulb and placed the setup at point-blank distance;
- temperature: I did this indoors, where the temperature was a controlled 20 C.

I let this go for 12 hours. I misted the setup with reverse osmosis water a couple of times to help prevent the paste from drying.

Here is the UV setup in action:

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...success! The case is lighter! Not 100% lighter but it is noticeable!

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Now here is the bad news. It looks like two different batches of plastics and/or dyes were used for the double shot key caps. Some, but not all, of the black, blue and red plastics were irreversibly bleached. This was not present after the first round of Retr0bright, but was very clear after the second round once the keys were washed and dried.

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The good news is that the legends did lighten. The bad news is that so did everything else. The beautiful deep red of the XMIT key is gone, and the remaining keys are inconsistently lightened.

So, my cautionary tale: I cannot recommend Retr0bright for double shot keycaps at all.

A friend of mine is a PhD student in chemical engineering and they understood the process pretty well at a molecular level. After some discussion we agreed that there is no good way to either selectively dye the black parts of the keys or selectively lighten the legends. In theory you could maybe coat the keycap with wax and carefully carve wax to serve as a mask but that is tedious and may not be effective.

So, even though it got lighter, I can't help but be disappointed in that I damaged a rare item. Failure is a cruel but effective instructor.

(Or I can call it "art".)

[seebart]

Thanks for the tips, I have several retrobright candidates. This will help me avoid some mistakes. I have understood that retrobright is never a 100% solution. And there are variables in the procedure of course leading to different results.

BTW your beautiful double shots still look nice![emoji6]

[Muirium]

The deeper lesson: ask the forum. I'm proud of my absence of craftsman's pride and will open threads before doing anything irreversible that I don't like the look of. They can then be a good place to document a project, like my AT thread, still in progress:

http://deskthority.net/workshop-f7/open ... t9791.html

I still haven't tried retrobright, for many reasons including the expense of H2O2 and the shocking lack of sunlight up here, but I certainly have read up about it and don't like everything I've found. The official website you mentioned likes to wax evangelical about its magic. Whenever I hear a one sided story like that, I know there's a missing half to the tale:

http://deskthority.net/keyboards-f2/ret ... t6084.html

Sorry to see your black doubleshots all messed up. Bleach can do that to many a black plastic (I've had coffee maker bits go wrong in the wash). The whole point of doubleshots is their amazing contrast, which yellowed legends can't even really undermine. I'd keep retrobright's magic strictly to beige monochromatic stuff, and take it slowly even with the inconvenience.

[seebart]

Good thing I a few "low end" yellowed keyboards like a Dell AT 102 that I will use as test runs when I get into retrobrighting.

[Muirium]

That's the essential problem with it: it's a technique better suited to experiments and low value stuff you don't mind ruining either in the process (or with serious dark sunburn a year or two later). I'm highly skeptical about its longterm good on something nice.

Yellow ABS is a great way to gauge the value of many old items, including space bars of course. The fact we can kinda sorta reverse it, for a while, doesn't wind condition back to NIB. Mention that you're selling retrobrighted hardware and its value rightly falls.

[seebart]

Yes I've seen threads elsewhere of retrobrighted hardware gone back to it's nice yellowish in varying time frames.
Apparently there is no long term solution.

[XMIT]

Right. My friend and I discussed the chemical process in some more detail. The root cause is the reaction of brominated additives. Bromine will grab oxygens (it is fairly electronegative) and generate yellow compounds. This is a spontaneous reaction that is accelerated with higher temperatures, presence of oxygen, and UV light. Removing say UV light would only slow, not stop, the reaction rate.

The now defunct Wikispaces page for Retr0bright is correct with its explanation. There is an archive.org link to it from retr0bright.com.

What I find fascinating is how different key caps were altered at different rates. There was no lightening of key caps for the first round.

[mr_a500]

This is why I have never tried Retr0bright - the possibility of permanent damage and the probability that it will just yellow again anyway. If it's a rare keyboard, then I wouldn't want to damage it - and if it's a common keyboard then I could just find a non-yellowed replacement.

I much prefer to get one that isn't yellowed to begin with because that also means it's much less likely to yellow in the future.

[seebart]

Of course there might even be people out there that like the yellowish color, or at least don't mind it.[emoji6]

[matt3o]

I don't know if it's because of the plastic I retrobrighted or the type of peroxide or the UV quality... but I've never had troubles with retr0bright neither with resurfacing of yellow. I've taken photos of keycaps retrobrighted 2 years ago that are still pretty much white.

[Muirium]

I bet the specific plastic is the big factor. Then how much UV exposure you've giving it now, and current heat.

Of course, my bias is showing: I loathe magic potion recipes where everything is significant and no one can explain quite how!

[seebart]

I don't know if it's because of the plastic I retrobrighted or the type of peroxide or the UV quality... but I've never had troubles with retr0bright neither with resurfacing of yellow. I've taken photos of keycaps retrobrighted 2 years ago that are still pretty much white.

Good to know. I need to use your method then!

[XMIT]

If you want to see the science start with this page, archived, linked through retr0bright.com:

http://web.archive.org/web/201208191858 ... BS+Plastic

Fortunately my chemical engineering friend is staying for the weekend so we chatted some more about the underlying process.

My related questions were: "Will this process affect the structural integrity of the material?" and "How deep does it go?"

We agreed that this is almost certainly a surface treatment. Even though ABS plastic is somewhat porous this is all staying close to the surface, on the order of 100 nanometers to 1 micron. So, the bulk of the plastic will be unaffected. (Dye sublimation for key caps goes about this deep.)

We don't believe that this process removes any bromine from the plastic, only causes it to react with something else. Temperature, UV light, and oxygen will all promote the reaction or the reverse reaction (yellowing, lightening). The oxygen dependency tells us that it *must* be a surface reaction. The bromine isn't going anywhere - this is why the yellowing comes back.

This agrees with:
http://web.archive.org/web/201207270445 ... m/Catalyst
"We are taking the oxygen away from the bromine using TAED and UV light, then replacing it with a hydrogen."

There is also advise on this site advocating a cool, humid environment under a UV lamp. This does agree with my findings.

[Halvar]

Interesting stuff, thanks for sharing!

On the Retr0brite page there was a warning linking the bleaching of dark plastics to additives in hair bleach products, but there's not very much context or explanation given:

http://web.archive.org/web/201207260420 ... d+Pitfalls (#4)

Seeing that you also used a hair bleach product, what do you think of this? Does it sound plausible to you? Was there Terpene in the product you used?

[XMIT]

No terpene - checked for that specifically. Ingredients were water and hydrogen peroxide only.

There was a cheaper version of "volume 40 developer" that has phosphoric acid (safe with ABS in low concentrations from my research). There is even cheaper stuff that has a bunch of thickening chemicals built in, e.g. stearic acid. Makes sense as these are designed for use with hair. I'd like to try those out on some scratch items to see if I can get the cost down. (Cindy had some really yellow Microsoft ergonomic mice that I'll pick up next time to try this out.)

The stuff I got was pricey - about $4.50 for 16 oz / 473 mL tax included. I used 125mL for the second round of treatment.

[XMIT]

Ah, to add - the lack of terpene combined with an identical result suggests to me that the page is wrong. I don't think terpene has as much to do with this as heat and temperature do. But I still don't know for sure why my keys got lighter, I can only speculate.

[fohat]

My experiences with Retrobrite have generally been pretty good with cases but lousy on caps.

I have assumed that it was because it was hard to keep them evenly coated and consistently damp.

Somewhere, recently, I read something on simply dunking the caps in the peroxide for "x" amount of time without any other chemicals or light.

[Muirium]

That's exactly what's going on here, as I recall:



The simple, straight H2O2 solution + light technique seems to be the safest retrobright gets. I wouldn't use it on caps besides heavily yellowed, light bodied ones like these, mind. It's always risky.

[andrewjoy]

the whole idea of the gel type retrobrite was to reduce the amount of it you have to make when doing a case. If you have enough of it pure H2O2 is better. You can also add some vanish oxi to it to speed up the reaction. The gel type stuff is not a good plan on caps .

[matt3o]

I never used the gel version actually and always added oxi (if that makes any difference)

[tlt]

Maybe you can rub off the miss coloring of the caps with something like car paint scratch remover. Hopefully it's just the surface that has changed color. Have not tried something lik that my self.

[Halvar]

Ah, to add - the lack of terpene combined with an identical result suggests to me that the page is wrong. I don't think terpene has as much to do with this as heat and temperature do. But I still don't know for sure why my keys got lighter, I can only speculate.

"Heat and temperature"?

You mean during the retr0brighting process? It doesn*t really become too hot IIRC, but I never used dark material which will probably become warmer.

I wonder if maybe some of the colors they used back then are just bleached by the peroxide in much the same way as the hair's melanine, by drawing electrons from double bonds.

[HaaTa]

Oh neat, another. I got a nearly NIB one from ascaii a while back.


https://plus.google.com/photos/11384566 ... 1302099137

I have...done worse things to rare items

I never did finish the converter code for this keyboard, but I vaguely recall it using some sort of 22 bit serial protocol.

[XMIT]

Thanks Haata. I will probably go the route of a controller replacement for this one, so long as I can get a controller to work with magnetic valve switches. I've got another magnetic valve switch keyboard in my queue as well.

[seebart]

Oh neat, another. I got a nearly NIB one from ascaii a while back.

that´s a beauty HaaTa!

[vekter303]

Hey,

So, Im looking at tackling a yellowed case with retr0brite.

Thing is, its my first attempt and there needs to be some research on formula and method, thats okay theres loads of good experience out there.

Other matter is this...

The case I have has some yellowing on about a third of the case only, at one end. Whether this is a concentration of bromine at one end of the plastic or selective UV exposure at one point I dont know.

What I need help with is finding out whether anyone has experience of a similar situation. My concern is that the lightening will be uniform and so there will still be a gradiated tone at one end of the case. I suspect that trying to isolate the worse affected area would be difficult, there is also a small area where the yellowing blends into a less affected area. I fear a blotchy or stripey result!

Anyone got experince here?

[Findecanor]

Welcome to the forum!
If your case is yellow only at one end then that was caused by selective exposure most likely.

Retr0bright should restore the original colour of the yellowed parts. If you are successful then it should all become the original colour — not brightened past that.
I think what happened to the OP was discoloration, at a point where the peroxide could not restore any more.
You should be able to avoid this if you don't overdose hydrogen peroxide and then check the progress at regular intervals so that you could stop in time.

BTW, there are other threads about retr0bright that are more recent than this.

[vekter303]

Thanks man!

Im really hoping thats the case. In my mind as much as only one area is badly affected and yellowed, I can imagine the whole case being lightened equally, basically leaving me with a lighter but uneven surface...

I guess its about avoiding the bleaching effect.

I have had a look at other threads and resources. In what context did you mean better?

[Findecanor]

I have had a look at other threads and resources. In what context did you mean better?

I was thinking especially about the use of heat instead-of, or in-addition-to UV.
One should take care with heat and ABS plastic though.

[mr_a500]

Has anyone seen this?

De-yellow using just the sun. I've tried it with many keyboards and computers and it seems to work nicely. I suspect that the yellow will probably return, just like with retrobrighting, but it's easy just to throw it back in the sun.

I haven't used it on anything too rare and valuable though. I'll be waiting a few years to see the result.