Introduction: Reversing UV Damage on ABS Plastic

Picture of Reversing UV Damage on ABS Plastic

Like so many others, I have been in love with Star Wars since I first saw the movies as a child. I also have a lifelong love for costuming. These loves finally came together in the mid 2000's when I first met some members of the 501st Legion at a convention (for those not in the know, the 501st is an international charity costuming club, specializing in the bad guy characters from a galaxy far far away). In 2009 I joined the ranks of the legion as TK-5246.

I am a Stormtrooper; clean, white, endlessly intimidating, or at least I was. Last year, after not trooping for a few months due to real life keeping me too busy, I pulled my armor from it's bin to discovery a trooper's worst nightmare. My helmet was yellow... How am I supposed to strike fear in the hearts of rebels if my bucket is a color that is synonamous with cowardess. After asking my fellow troopers I discovered that it is a fairly common occurrence, I had three options. I could paint my armor white, attempt to wet sand the top layers of plastic off, or convert it to a sand trooper. None of these were appealing. If you paint your armor once, you can plan on repainting it after every few troops, paint does not adhere well to ABS. Sanding is a lot of pain staking work, with no guarantees that I wouldn't ruin my armor. And if I wanted to be a Sand Trooper I would move to Tattoine.

While on the internet looking for ways of dealing with this cruel twist of fate I discovered Retr0bright. It's an open source formula of ingredients available at your local grocery store developed by vintage computer collectors. It supposedly reverses the process of UV discoloration in ABS. I thought surely there would be hundreds of threads about this on the 501st forums but alas, there were none. Some people mentioned it as a possibility, but it seemed most everyone stuck with the tried and true methods I spoke of earlier. After much debate with myself, I decided I had nothing to lose. I got my materials and tried it. The results are like magic, read on to see how I went about it.

Step 1: What You Will Need

  • Rubber gloves
  • Paint brush
  • Some sort of blender (I used a stick blender)
  • Retr0bright (ingredients and formula in the next step)
  • UV light source (mine was a CFL reptile light available at most pet stores)
  • Miscellaneous measuring spoons and mixing vessels
  • Yellowed ABS, in this case a Stormtrooper helmet.

You will not want to skip the rubber gloves. As you can see in the photos, I did not wear them. I ended up bleaching the tips of my fingers before I put some on. High concentration hydrogen peroxide can be nasty stuff and can lead to fairly severe chemical burns.

Step 2: Ingredients for and Making the Retr0bright

Picture of Ingredients for and Making the Retr0bright
  • 1- 16 oz bottle of 40 volume hydrogen peroxide (available at hair salon supply stores)
  • 2 heaping tablespoons of xantham gum (I got mine at Walmart)
  • 1 level teaspoon of glycerin (available at most pharmacies)
  • 1/4 teaspoon of Oxyclean or similar laundry booster

Combine the peroxide and xantham gum in a blender, or in my case a ceramic container for use with a stick blender. Mix for 5 seconds on high. Add the glycerin and blend for another 5 seconds. Let this mixture rest for a minute to hydrate the ingredients and then mix again for 5 more seconds. When you are ready to get started add the Oxyclean and blend again. What you are left with is a gel that can be painted on to your surface.

I will say that this makes enough Retr0bright that I could probably have done 5 helmets, so you may want to scale down the recipe.

Step 3: Application

Picture of Application

I applied the Retr0bright with a paintbrush, making sure to get a fairly even coat over the entire surface. It should not affect any paint or the vinyl decals, so I painted right over them. I then placed the helmet under my UV light. You can also do this outside on a sunny day. However, you want to be careful that your helmet doesn't get too hot in the sun or it will damage the plastic. I decided to play it safe and use a reptile light, it also gave me the ability to leave my helmet unattended without worrying about something happening to it (like a dog thinking it looks fun to play with).

I left it under the light for about 12 hours, rotating it every couple of hours.

After retrieving my helmet from it's basking spot it needed to be cleaned up. The Retr0bright dries on and can be a little difficult to remove. Scrubbing for a couple seconds, a small area at a time with a little diluted dish soap and a toothbrush then wiping it off with a paper towel did the trick. I probably could have put it in the bath tub or sink and hit it with a sprayer to make things easier, but I have a wireless mic and fans installed in the helmet that I did not want to remove.

Step 4: Science and Retr0bright Info

The yellowing of ABS when exposed to Ultraviolet light is the result of a flame retardant added to the plastic during the manufacturing process. The most common of which is tetrabromobisphenol –A, or TBBP-A. When exposed to UV light the TBBP-A degrades allowing Bromine to become a free radical. The bromine forms a bond with readily available oxygen and causes the yellow color.

By irradiating the ABS with UV light in the presence of more hydrogen atoms, in the form of hydrogen peroxide, we break the bonds between the oxygen and bromine and allow the bromine to bond with the hydrogen, thus reversing the discoloration.

I encourage you to check out the Retr0bright wiki and learn more about the folks who came up with this. It is people like this, who figure these things out and make them available open source that keep maker communities like ours thriving.

Step 5: Results

Picture of Results

The results were better that I could have expected. It looks like a new helmet again and I am excited to go back to proudly serving the Emperor.

Thanks everyone for reading, and I hope this helps some of my fellow Troopers keep the galaxy safe.

With unquestioned loyalty,



Kessa33 (author)2017-05-21

Typo correction: "need to sit it".... that should have said "need to fix it"!

Kessa33 (author)2017-05-20

Thanks for sharing! My armour is nearly 10 years old and sadly got to the stage where I need to sit it.

I'm curious about one point I hope you can help with; I've read the comments about needing to repeat the process at some point in time... but what I'm curious about is whether performing this process actually speeds up yellowing occurring in future?

For example:
It took years for my the original untouched abs to yellow.... (Its mainly affected the "high points" such as top of the lid, bridges, top of the chest plate, top of the shoulder bells etc)
.. whilst fixing those it makes sense for me to treat the whole armour at the same time to ensure it's a consistent colour/seamless blend.

However I'm concerned that doing so could actually speed up the discolouration of those (currently less affected) areas in future.

How long have you found your newly cleaned abs lasts before the same level of yellowing reoccurs? I saw 1 comment above say he's now having to repeat the process every month which seems to tie in with my concern.

I'd love to know what other people have found.


menuhin (author)2017-03-08

Nice guide.

Perhaps this is a better explanation of what is going on for Retr0bright:

chrisdojo (author)2016-06-23

What type of light bulb brand or wattage did you use for reptile UV light? please

monsterlego (author)2016-04-20

My lego collection actually suffers from this, this is really hepful

monsterlego (author)2016-04-20

My lego collection actually suffers from this, this is really hepful

ThomRaven (author)2016-04-13

Thanks for posting this. It's extremely helpful!

tvazquez2 (author)2015-11-05

Nice ible! I would love to try it to brighten my Gundam models. I bought them (used, already assembled) from a fellow collector and they were already yellowed. Good thing they didn't have decals applied to them.

TK-1214 (author)2015-10-29

Although this seems to be a pretty good way to get my armour white again, it won't save my trooper from decaying ;-) I'm trooping now since 1999 in the 501st, and after all this time the ABS has become old, crackly and brittle. So I'm wondering how long it will last...

Crafted298 (author)2015-09-18

Did you buy or make your armor?

RickO4 (author)2015-09-08

Will try this at once! Thanks.

TK 1552

JohnH116 (author)2015-08-27

So I'm going to assume I'm not alone among the grateful troopers that have read through the comments and said "acrylic lacquer!?!?!?" when they read mfilos comment below. ☺ not that it's a bad idea, but it is rather permanent and I'm thinking if any yellowing does happen again your screwed. Now I say this in total paranoia and it may be a moot point, but has anyone had luck with alternatives? Such as Anovos plastic Protectant or something similar? I'm about to plunge into what has become a repetitive process for me. Since my second treatment, my armor seems to be yellowing within a month. It's crazy. Anyone else hitting this frustration? Anyways. Routine for now to get ready for troop shenanigans. ? ? And Thank you for a great instructable. At least it's breathing new life into an old kit.

TexBC (author)2015-08-20


Your posting is the most in depth version I've seen on the internet, and I've been to the retr0bright site, too. Nice job!

How well does this work on different colors of plastic? I have an old Japanese toy made by Gakken called the Mospeada 1/8 Ride Armor. The chest and crotch areas of the rider, and the side of the bike have yellowed. I rarely removed it from the box, but the box has two windows exposing those two areas I mentioned. Most of the toy is an aqua-marine/turquoise color. So I am wondering what would happen if this stuff was applied to it. I wish the box had a gate fold!

This is a toy I've had almost 30 years and I desperately would like to return it to its original condition. It is pretty much mint, except for the discoloring.

Any help would be greatly appreciated. Help me Obi-Wan Kenobi!

GRitter (author)2014-10-28

This is a great instructable and all, but what do you use to clean the blood of the honorable rebel soldiers from your hands?

jelte1234 (author)GRitter2015-06-06

I believe hydrogen peroxide works great for that too!!

Stasz (author)2015-05-30

TB-60609 reporting in.

I've just begun researching a solution for my slightly yellowing Scout bucket, and was thrilled to come across your instructable.

I'm trying this out tomorrow. Thanks for sharing!

lschwartz (author)2015-02-10

Other objects definitely subject to sunlight and yellowing is model sailboats and airplanes!

Androxilogin (author)2015-01-24

Hmm.. I'm thinking about trying this on an old Super Nintendo console. Very interesting, thanks!

chouser4 (author)2014-12-28

Great instructable. Thanks for sharing

harmonious1 (author)2014-10-31

CowardICE. Just sayin.

I liked your instructable.

ManifoldSky (author)harmonious12014-11-03

And "painstaking". As in the taking of pains.

throbscottle (author)2014-10-31

This is brilliant - thanks for sharing, and thanks to Merlin and friends for inventing!

jmacdonald13 (author)2014-10-31

Nice instructable, I love stuff like this, I just wish I had something I hadn't thrown out to clean up. :-) Thanks.

MichaelAtOz (author)2014-10-30

What's with the black goatee?

SpectreGadget (author)2014-10-30

Great instructable and very timely for me! I was TK034 (retired) but have pulled out the costume for my son and noticed that the bucket has yellowed a bit. I've actually used this formula to restore an original Apple Macintosh Portable, so I've seen it work in person, although I used a weaker solution for that job. Thanks again!

JohnnyLightning (author)2014-10-30

To author and Dave (Merlin)...Fantastic!!

covalt.r (author)2014-10-30

great idea. how will it work upon other colors to remove similar staining?

ElectroFrank (author)2014-10-30

Basic Army Technique: keep the soldiers quiet by giving them uniforms and equipment that need excessive cleaning and maintenance.

But of course with a black helmet, I suppose Darth Vader never has this problem ?

MacCupcake (author)2014-10-30

You are my savior! I just purchased a $2000 sewing/embroidery machine that looks like it sat in bright sunlight for the past two years! It will do wonders to make it look new again.

I also have several old Macs that can use it. I am going to spending a lot of time with this in the coming weeks!

Cheese Queen (author)2014-10-30

There are LOTS of ABS things out in the world that are yellowing, including bathroom fixtures in RV's and mobile homes. In fact, I have a garden tub that is only 6 years old but yellowing- I'm going to try this!

Retr0bright (author)Cheese Queen2014-10-30

I know - it's been taken up by the Lego community, Transformer toys, Airstream caravans, sneaker soles, vintage radios, the list goes on and on. Most people don't know how widespread the use of ABS plastic is. There are some good galleries of photographs on the Wiki.

askjerry (author)2014-10-30

Very nice to know for many ABS items. I'll be sure to bookmark this instructable.

(And share with our local ATX Hackerspace.)


Raphango (author)2014-10-30

Interesting! =D

Lovelikeatruck (author)2014-10-30

Good catch. It is now corrected, thanks.

mfilos (author)2014-10-29

Since it's rather important imho, I'm re-posting a thread taken from "Amibay" forum where Merlin (Retr0bright's Wiki author) posted the following:


Sometimes I get e-mails from people that complain that their Retr0brighted parts have gone yellow again over time. Rather than put this in the support thread where it may get lost over time, I thought that if I made it a separate sticky, it may get noticed more.

So, why do the parts go yellow again? It's for a couple of reasons. I shall explain below.

Firstly, I stated in the Wiki that the chemical reaction is reversible; that's why we are able to reverse the yellowing that has occurred over time. The downside of this is that it can also revert back, as it's reversible and can go in either direction.

The second reason is that Retr0bright only treats the surface, it can't penetrate into the plastic where more of the fire retardant is present. Unfortunately, the fire retardant can migrate through the plastic and this is another reason that yellowing can occur again, as more migrates to the surface.

Is there anything that can be done about this? YES, and it's the part of the treatment that most people seem to forget.

Just as the Triangle of Fire needs fuel, oxygen and a source of ignition, the yellowing of the plastics needs three things; The flame retardant, UV light and oxygen - the oxygen is in the air we breathe. Take the oxygen away from both triangles and you don't get a fire and you don't get yellowing, either. How can you do this?

The answer is quite simple. Once the parts have been treated, you should coat the parts in a coat of clear, satin finish acrylic lacquer. This has the effect of cutting off the oxygen supply to the fire retardant and will prevent further yellowing.

For added insurance, you should use an acrylic lacquer that includes a 'UV Blocker' or 'UV Filter'. These products contain a chemical called an 'up-converter', a chemical that has the neat ability to take light in at one wavelength and give it out at another completely different wavelength, in a similar way that fluorescent colours need UV light to make them 'glow'. By shifting the wavelength of the UV light via an up-converter you effectively 'turn off' the UV light, that stops the bromine molecules from vibrating and gaining enough energy to drive the yellowing reaction.

Up-converters are used quite widely in plastics these days for this very reason, however, they weren't used in the master batches back when our machines were built and by using a lacquer containing an up-converter, you are retro fitting the answer to the problem.

This is about as close as you will ever get to a permanent fix for the yellowing problem and I hope that it helps those people who have been disappointed to find that their cherished parts have started to discolour again.

Common$ (author)mfilos2014-10-30

Thanks for posting this. The same thing goes for yellowed vehicle headlights. Once the oxidation and road grime is polished off, you're basically starting from scratch with a substrate that will yellow back out unless it's protected. I have always clear-coated head and tail lights in my cars with automotive clear and they do not yellow or oxidize. They stay clear and bright and are super easy to polish out subsequent times with the bugs take their toll on the head lights. Every time I suggest clear-coating plastic lenses, I am met with blank stares and confusion. It's not rocket stop oxidation by sealing the parts off from oxygen.

Retr0bright (author)2014-10-29

Hi, I'm the guy that wrote the Retr0bright Wiki, also known as Merlin. Thanks for taking the time to try this and prove that it really works, despite the nay-sayers that doubted it.

We were labelled heretics at the time we wrote the Wiki and we were told that this was impossible, but impossible only lasts until you figure it out. This is extremely customised chemistry, designed to one job very well indeed. It's been said that "Any technology sufficiently advanced should be indistinguishable from magic" and Retr0bright is proof of this.

The Wiki has pictures of my 1983-vintage Commodore 64 that was a test bed for Retr0bright. It was mahogany coloured after all that time, but not any more...

"This is not the yellow you've been looking for..."

[Jedi finger sweep]

Dave (Merlin)

I appreciate your taking the time to comment on my Instructable! Thank you for all the work you and your colleagues did to come up with this.

It is easy to see why there are all the nay sayers, it really seems too good to be true. I had been on your Wiki many times before I finally built up the courage to try it on my precious armor, and I know there are other troopers like me who are in the same position. It really is like magic, it is unbelievable how well this works, and I know that it had to have taken a lot of effort on your part to perfect this technique!

It is people like you, who develop this kind of science and make it open source that allow maker communities like Instructables to thrive.

Thanks again

camilacavieres (author)2014-10-29

As I'm a restorer and a big Star Wars fan...You make my day!

walter.warren1 (author)2014-10-28

Interesting. So the yellowing is just a chemical reaction that the paste reverses causing it to disappear? Or is the paste absorbing the yellow discoloration?

alter2000 (author)walter.warren12014-10-29

From what I read in here, it appears that bromine breaks the bond with the CH (or CH2)(that is the radical between bromine and the rest of the molecule) by UV light and then bonds with the hydrogen in H2O2 and forms BrH, leaving only bisphenol (or another phenol; I'm not sure) on the helmet's surface, and I guess it can be removed by rubbing that part with cardboard (or another mild abrasive), but this increases the chance of having to 're-whiten' the ABS surface (in this case, the helmet) again and again, due to the crevices formed. But I'd still go for that yellowish look if I decided to keep it more as a relic of a forgotten time (when 32 MB were just like a TB today.I miss those times).

alter2000 (author)alter20002014-10-29

Sorry, I meant BrO, and it's the oxygen that comes out. Hope I helped.

nedchem (author)walter.warren12014-10-29

It's a chemical reaction. The formula is essentially a super oxidizer that's creating lots of very reactive free radicals.

The yellowing is the result of the breakdown of the flame retardant added to ABS, which is greatly accelerated by UV radiation. The Retr0bright combined with UV light causes a chemical reaction that eliminates the yellow.

BambiKiller (author)2014-10-29

Outstanding, I heard about this before but didn't know the details. Thanks for the tutorial.

Ripcode66 (author)2014-10-29

TC-9296 here. Nice write up!

Darth_Adakar (author)2014-10-28

Excellent!!! I use just Hydrogen peroxide to clean my dremcast just let the plastic pieces one night and the next day washed with water and voila!.I´m gonna try with your instructions.

walshlg (author)2014-10-28

Is this like sun tea (you really don't need any sunlight just time)? Just wondering on whether the uv light does anything useful, did you try this without the light?

Lovelikeatruck (author)walshlg2014-10-28

I did not try it myself with out the light, but ultraviolet radiation is integral to creating the chemical reaction that reverses the damage. If you don't have access to a reptile light you can leave your object in the sun, it will give the same effect.

mmestre (author)2014-10-28

TK 5096 here. THANK YOU for posting this!!!!

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