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bigbarada
01-26-2010, 09:33 AM
I was looking to see if there was any way to prevent or even remove yellowing from the bubbles on carded action figures and I ran across this site that claims they found a method of actually removing the yellowing from vintage action figures.

So I'm just wondering if anyone knows about this? Has anyone tested it out? If so does it really work?

http://www.comicbookbin.com/Action_Figure_Yellowing001.html

For anyone who doesn't want to click the link, the process involves submerging the figures in a chemical called Hydrogen Peroxide 35% food grade, then placing the submerged figure in direct sunlight. Supposedly the process will completely remove the yellowing from the white plastic without discoloring anything else.

Obviously this is not going to work that well if I want to "de-yellow" (or "de-brown" in the case of some POTF figures) the blister on a MOC figure.

But of course, who knows what effect this might have on the plastic 10-20 years down the road. I'm almost tempted to buy an old, yellowed Stormtrooper figure on Ebay just to test this out.

Also, if anyone has any advice for how to display a MOC vintage figure in a way that will prevent the bubble from yellowing, I'm all ears. And locking it away in a closet, never to see the light of day, is not really an option. :)

LusiferSam
01-26-2010, 11:28 AM
Yes, I've heard of this and tried it. But not with any SW figures. There was a lot of about this process this past year on another SW site. One of the pages I read that describes how to said works very well with ABS plastics. Well because I have tons of ABS in the from of Lego brick I whitened some yellowed legos. But I'm extremely concerned about the long term effect I'm running a five (or longer) experiment.

I found six highly yellowed white from an old set. They're very common bricks so I'm not worried about damaging them. Two of the bricks are controls: unwhitened, untouched, and stored in a cool dark place. The other four were whitened in 3% hydrogen peroxide for 3 days. All four whitened up nicely, looks just like new. Now of the the long part. Two of the whitened bricks are being stored with the controls. The next is being stored out in the open of my bed room. And the final brick is being kept in as direct sun light as possible. They will be check very six months for the first two years and then once a year after that.

Again I worry about the long term effects.


The yellowing is triggered by UV and heat through a process called photo-oxidisation and thermal-oxidisation respectively. The polymer (usually ABS, Acetate or PVC) absorbs UV causing oxidisation of the molecule, this causes Carbon bond conjugation (cross bonds and double bonds) which will weaken the structure, make it brittle and change the plastics relative permeativity to visible wavelengths of light thus changing its refractive index giving it the yellow hue. The polymer also can contain residual catalyst from the production of the polymer - depending how much is left in the plastic this will accelerate the photooxidastion of the plastic - this why I assume 12 backs rarely yellow but POTF bubbles often yellow.

The point is that once degradtion has started the process can go into a positive feedback loop with the available free oxygen - this combined with heat can accelerate yellowing even in dark environments free of UV.

Now as to whether Hydrogen Peroxide (H2O2) can reduce the polymer(remove O or add H), even with my limited chemistry knowledge I doubt it - even if it could, thermodynamically I think it is unlikely to reverse Carbon conjugation and return the polymer to its former glory. I suspect the H2O2 is causing another reaction that maybe just as bad or even worse. This may cause an acceleration of degradation long term.

EDIT: Oh, I have no idea where you would buy 35% peroxide. Any thing over about 10% can cause chemical burns. 35% would be very dangerous handle.

Maradona
01-26-2010, 12:05 PM
Peroxide is a bleaching agent, I believe.

bigbarada
01-26-2010, 12:11 PM
Well I'm glad someone is in the process of testing this out. :) How long has it been since you soaked the bricks? Any noticeable differences yet?


The polymer also can contain residual catalyst from the production of the polymer - depending how much is left in the plastic this will accelerate the photooxidastion of the plastic - this why I assume 12 backs rarely yellow but POTF bubbles often yellow.

So if I have a 25 year old carded figure and the bubble hasn't started yellowing yet, then can I assume that it never contained much of this "residual catalyst" and, as long as I keep it out of sunlight and excessive heat, then it won't suddenly start yellowing on me?

I think, just to be on the safe side, I'll probably buy one of those AFA cases with the UV protection for my Barada figure.

bigbarada
01-26-2010, 12:14 PM
Peroxide is a bleaching agent, I believe.

Which is why it seems so odd that it wouldn't affect the colored plastics.

LusiferSam
01-26-2010, 01:15 PM
Well I'm glad someone is in the process of testing this out. :) How long has it been since you soaked the bricks? Any noticeable differences yet?
I started in late June, so the six month mark has come and gone. So far, nothing. Which is what I would expect. New plastic doesn't yellow that quickly. I would hope to start seeing a difference after about 4 or 5 years. I'll see if can post the crappy photos I have.


So if I have a 25 year old carded figure and the bubble hasn't started yellowing yet, then can I assume that it never contained much of this "residual catalyst" and, as long as I keep it out of sunlight and excessive heat, then it won't suddenly start yellowing on me?
That's not an idea I'd place money on. The current thinking the vintage community is that cheaper plastic was used in the the ROTJ and POTF bubbles. As to what made it cheaper I have no idea. While the Sun is the primary UV source which triggers photo-oxidization, it's not the only source. Some lighting gives off weak UV (fluorescent lights for example). And some of this things might just be a matter of time. Less "residual catalyst" might just mean slower yellowing.


Peroxide is a bleaching agent, I believe.
More properly it's an oxidizing agent. Produces like Clorox 2 or OxyClean use peroxide and are "oxygen bleaches." I don't remember the chemistry but something about the oxygen reacts differently to pigments than chlorine does. I think chlorine tend to make more reactive oxygen ions and bleaches things faster, hence the loss of the color. Where as peroxides are slower and less reactive. Again I think, I don't remember the exact chemistry off hand.

bigbarada
01-26-2010, 02:01 PM
That's not an idea I'd place money on. The current thinking the vintage community is that cheaper plastic was used in the the ROTJ and POTF bubbles. As to what made it cheaper I have no idea. While the Sun is the primary UV source which triggers photo-oxidization, it's not the only source. Some lighting gives off weak UV (fluorescent lights for example). And some of this things might just be a matter of time. Less "residual catalyst" might just mean slower yellowing.

That's kind of what I was thinking because I really have no idea what kind of conditions this toy has been stored in for the last 25 years.

I did know about the UV given off by flourescent lights, so I replaced all the compact flourescent bulbs in my room with standard incandescents. The environment will just have to suck it up a little longer. ;)

LusiferSam
01-26-2010, 08:54 PM
I did know about the UV given off by flourescent lights, so I replaced all the compact flourescent bulbs in my room with standard incandescents.

Be careful. Some incandescence also give off UV. Any type of source that is labeled "Full Spectrum" is likely going to have a little Near UV. Halogens in particular would have this feature. You're standard 60/100 W tungsten filament should be ok as they should peak in the IR and should fall off before reaching the UV.

Darth Jax
01-26-2010, 09:30 PM
when halogens were at the height of their popularity, most 'lamps' included a filter to block restrict the wavelengths of light emitted (or at least the ones i saw had them)

Lord Malakite
01-27-2010, 04:47 AM
An oxidizing agent works by breaking the chemical bonds of a chromophore, or the part of a molecule that has color. This changes the molecule so that it either becomes colorless or else reflects a color outside the human "visible" spectrum of color.

LusiferSam
01-27-2010, 05:20 PM
when halogens were at the height of their popularity, most 'lamps' included a filter to block restrict the wavelengths of light emitted (or at least the ones i saw had them)
Filters have a responses function, they don't just sharply cut off 4200 (violet). If a light source puts out blue or violet light you're likely to have a little UV leakage.


An oxidizing agent works by breaking the chemical bonds of a chromophore, or the part of a molecule that has color. This changes the molecule so that it either becomes colorless or else reflects a color outside the human "visible" spectrum of color.
Ok I knew that, but why is oxygen bleach "color safe" chlorine bleach not? Both are oxidizing agents and both work be altering the bonds in the chromophore molecule, right?

Lord Malakite
01-27-2010, 06:08 PM
Ok I knew that, but why is oxygen bleach "color safe" chlorine bleach not? Both are oxidizing agents and both work be altering the bonds in the chromophore molecule, right?

Both chlorine and oxygen bleaches are similar. Both are oxidizing agents and work in a similar method, they break down the double bonds of carbon which are usually responsible for "color". It just comes down to the strength of the oxidizing agent in the bleach. The whole "color safe" thing is just a trade-off of using a weaker oxidizing agents.

Chlorine bleaches don't usually contain chlorine directly. Rather they usually contain sodium hypochlorite which is one of the products created when sodium hydroxide (in solution) reacts with chlorine. Sodium chloride, or common "table salt", is also created. Sodium hypochlorite is considered a strong oxidizing agent.

Oxygen bleaches on the other hand contain slightly weaker oxidizing agents, like hydrogen peroxide for example. Being weaker they can oxidize the chromophores in typical stains as they are usually weak themselves, but they aren't usually strong enough to break down the chromophores of commercial dies used to color fabric as those bonds are much stronger.

Maerj2000
01-27-2010, 09:07 PM
In addition to Star Wars, I collect another toy line, the Micronauts. They were pretty popular in the 70's and many of the vehicles were molded in white plastic. Over time, some of them yellowed. But I managed to turn them white again with some Retro Bright.

http://retr0bright.wikispaces.com/

I used Tezza's alternate recipie:

1/2 pint (200 ml) Hydrogen Peroxide, 6% strength
2 heaped tablespoonfuls of "White Crest" Arrowroot
1/5 teaspoonful of "Oxi-Magic" laundry booster

I used over the counter Hydrogen Peroxide, 3 % I think. I WOULDN'T use the full strenght peroxide, I think that it might have adverse effects on your stuff.

I used Oxy Clean powder and Arrowroot powder. The arrowroot makes it into a gel which you can spread onto your figures or whatever. Be careful with it, it turns everything white! You may want to experiment with this stuff on something you don't care about first but it worked for me.

Maradona
01-27-2010, 10:55 PM
This sounds promising. When I get the chance, I'll try this on my yellowing Jetfire.

LusiferSam
01-29-2010, 08:56 PM
That's how I thought chlorine and oxygen bleaches worked. I mostly remember the chemistry for chlorine bleach, but really didn't know the oxygen bleach chemistry (which when I worked out a basic level didn't seem right). I knew it had to be a trade off in terms of oxidizer strength and strength of stain's bonds.

The retrobright site is the one I found this past summer, but then lost. It's because of this site I thought trying it on Lego bricks would be a good idea (ABS plastic). I didn't really get a chance this summer to really read the page. But after spending some time there, I'm very impressed. I think there is some good science behind what they are talking about. I completely missed the part on using TAED (tetra acetyl ethylene diamine) as a catalyst. I'm looking forward to try this with some other Lego bricks. There's some gray and blue bricks I really want to test now. Maybe next weekend, as I'm out of town right now. A black light might a really good idea. A little more control and I can run it in the evening or over night.

Maerj2000
01-29-2010, 09:04 PM
Good luck to everyone. It worked well for me. I had a Micronaut battle cruiser with some white parts, some yellow, and some that were somewhere inbetween. After tratment they all look uniformly white.

The arrowroot makes a gel that can be spread evenly over the parts. Its seems to get rubbery pretty fast so don't wait too long before applying. The powder oxy clean didn't like to mix to well as I recall, it was sort of gritty.

I soaked some parts in a solution of hydrogen peroxide and oxy clean. This did bring out the brightness a bit more but if you leave it in too long it crystalizes. I was able to chip it off but just thought I'd let everyone know in case they attempt the same thing.