Answer: Photodegradation (from exposure to UV rays) and thermal oxidation (from exposure to the air) cause certain plastic mixes to change color over time.

Something you’ve probably noticed is that certain action figures of yours that were once white have changed over the years to a shade of yellow—bordering on brown. Maybe you’ve tried to clean your figure, thinking that this must be some kind of stain, but it’s not. The color of the plastic has actually changed. Maybe this change went unnoticed for a long time, or maybe you pulled your figures out of a tub one day, like I did, and noticed that some didn’t look quite like how you remember them.

The action figure pictured below is Red Alert from the Transformers Cybertron line. I got this figure back in 2005. At the time I wasn’t aware of the effects the sun and other environmental factors had on action figures, so it sat among the rest of my collection on a shelf, exposed to sunlight. Eventually, I realized the sun isn’t good for your figures, so I moved the display to a part of the room where the sun light would not be hitting my action figures at any point during the day. Later on, when my collection got so large that displaying all my figures became a hassle, this figure, along with many others were moved to “long term storage” and have spent the last six or seven years in plastic tubs. I can say with certainty that this figure was not that dark of a shade of yellow when I stored it away.

So what happened? Obviously the sun had its effect during those years of the figure being on display; this is apparent by the uneven distribution of the yellowing. But what about the years following—when the figure was no longer on display, yet somehow, the yellowing continued. How did the degradation continue even after the figure was stored away? For years I thought the only way for figures to experience this much degradation was to leave it out in the sun. Day after day. Month after month. Year after year. But it was stored away, so what happened?

This chemical reaction occurs between the UV radiation, oxygen, and certain chemicals in the plastic. This is called photodegradation. This along with another process called thermal oxidation are the main culprits.

Exposure to Ultraviolet Light and Oxygen

When you look at a figure that has yellowed, what you are are seeing is the result of a chemical reaction. The main culprit is ultraviolet light. Not only can UV light be hazardous to your health, but as you can see, it can also be hazardous to your collection. Sunlight is responsible for not just the degradation of action figures, but pictures, painting, old electronics, and various other collectibles. There is a chemical reaction between the UV rays and certain chemicals in the plastic mix. This chemical reaction between the UV light and a chemical in the plastic called Bromine (more on this later) is the reason why certain action figures start to turn yellow and even brown over time.

Thermal oxidation is the second component. This occurs when certain chemicals in the plastic are exposed to oxygen. While this process is ultimately unavoidable, you can slow down the process by keeping your plastic collectibles out of the extreme heat (which will speed the degradation up).

While you can reduce the effects of the aforementioned processes, ultimately, its very difficult to prevent all exposure to UV light and nearly impossible to stop the thermal oxidation from happening. Over the years, its likely that certain figures are going to see this color change despite your best efforts to shield them. Its sad, but true.

Why Do Certain Figures Turn Yellow and Others Don’t?

While its difficult to give an exact answer pertaining to action figures specifically, the question has been explored in detail regarding old gaming systems. In this article from Vintage Computing and Gaming, the writer goes into detail about what he found while researching the effects on his old Super Nintendo (SNES) console. One console turned yellow over the years, and the other did not. After consulting with some experts, he found that the plastic making up certain SNES cases was composed of ABS (acrylonitrile butadiene styrene). ABS is combustible, but cheap so manufacturers use it to save money. To deal with the combustibility of ABS, they include flame retardants in the plastic mixture. One of the chemicals that is used frequently is Bromine. Bromine reacts with the UV rays and oxygen in the air. A chemical reaction starts and continues indefinitely until the console case has changed color. This is just a short summary of the process. I highly recommend reading the whole thing here www.vintagecomputing.com.

It is likely that a very similar process is taking place in certain action figures of ours, and to answer the original question about why certain action figures turn yellow and other do not under the same conditions; its likely that different batches of plastic were use to make the figures. One batch was simply a better mixture than the other.

How To Stop Your Action Figure From Yellowing

In short, there is no way to completely prevent your action figures from yellowing if the plastic mixture used is predisposed to it happening; however, you can take preventative measures that will significantly delay the inevitable.

1. Keep Your Figures Out of Direct Sunlight

I’ll admit when I first found out about the effects of sunlight on my figures, my first reaction was to put them all in tubs and store them away from the sun forever. This is an extreme reaction especially because of the whole chemical reaction thing discussed earlier—once the process starts, its kind of hard to reverse so you might as well enjoy your figures and display them. There are some smart ways to go about doing this though. If you want to display your action figures, make sure they are displayed were the sun is never hitting them. Better yet, pick the room in your house that gets the least amount of sunlight. Also, consider keeping the blinds closed during times of the day when the sun is brightest.

I’ve written a whole article about how to display your figures and also protect them from those harmful UV rays from the sun. Check it out here.

2. Store Your Figures in a Climate Controlled Environment

In addition to keeping figures out of the path of harmful UV rays, its also a good idea to keep them stored in moderate, not heavily fluctuating temperatures. Extreme temperature further damage your figures over time. Specifically, very hot temperatures will speed up the degradation of the plastic through thermal oxidation. As I demonstrated with the pictures I showed, even when your figures are stored away and out of the sunlight, its still possible that the climate itself could effect them. The figure I showed above was stored in my closet. There is a “door” to my attic inside my closet—its actually more like a wooden board that blocks the door way. My closet is hotter in the summer than the rest of my room and colder in the winter, and is more humid most of the time than the rest of the house. I should mention that I had some old figures that I had stored in my attic for a while, and they experienced yellowing much worst than the one I have shown in the post. Unfortunately, I sold those figures a while back and I don’t think I have any pictures of them.

Whether you are displaying them or storing them away, keep them in a room where the temperature can be regulated. A closet or a finished basement are probably some of the most ideal environments. In most cases some of the worst places you can keep your action figures are in attics, unfinished basements, and the garage unless you are able to regulate the temperature and humidity.

What Kind of Lights Don’t Produce UV Rays

Incandescent Light Bulbs

Though UV rays are still emitted from incandescent light bulbs, incandescent light bulbs are designed to emit less UV rays and are a better choice for lighting your collection than florescent lights, which produce significantly more UV rays. Be aware that incandescent lights get hot. Heat is not good for your action figures either, therefore its recommended that if you are using incandescent light bulbs to shed some light on your collection, keep the source of light at a safe distance or else the heat could end up damaging the figures.

LED Lights (Light Emitting Diode)

LEDs are a favorite for jazzing up your displays for your collection, and though there seems to be a misconception that LEDs produce no UV radiation, thankfully the UV emission from LEDs is very low. This is due to the ultraviolet light being converted to white light by the phosphers in the LED bulbs. In fact, museums and other businesses have started using LEDs as their primary light source in order to prevent damage to their inventory.

How to Reverse the Effects Once It Happens

The most common treatment for yellowing action figures is done by using hydrogen peroxide. Simply place your action figure(s) in a clear glass jar and then fill the jar with hydrogen peroxide. Now place the jar in the sun and let it sit for a period of days. The length of time may depend on the concentration of hydrogen peroxide used. Once you determine that its time to take them out, wash them off well to get off all of the peroxide as it will leave a white residue on the figures otherwise.

Some recommend using highly concentrated peroxide such as 20% and up to even 40%. The process will be faster and more aggressive depending on how concentrated the peroxide is. The benefit to using a lower percent solution (6% for example) is that the process is slower and more easily monitored, so you can be aware of paint on the figures possibly dissolving during the process. Higher the concentrations can dissolve the paint at a faster rate.

Take adequate safety precautions when working with hydrogen peroxide, especially highly concentrated hydrogen peroxide as it can cause burns and be very harmful to your eyes if you get splashed. And I don’t think I need to tell you not to drink it, but just to be clear: DO NOT DRINK IT!

This is the most common treatment and many people seem to have success with it; however, some report the figures revert to the yellowed color only two years after the treatment. I have also seen some people claim that the treatment worsens the discoloration—I don’t think this is the common result, but it seems to be possible. These are all things to keep in mind before treating your figures. There are some other methods of dealing with this, but the hydrogen peroxide treatment is the most common. I will cover the other methods in a future post.

If you’re thinking of packing your action figures away for longer term storage, but are worried about discoloration occurring, I go over some storage methods that should at least mitigate that process in this post.

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