Sure, consoles age and get dirty. Heck, I remember a suspicious incident involving my Super Nintendo (SNES) console and a can of Coca-Cola in the early ’90s that left my SNES looking more like a moldy loaf of bread than a video game system. But around five years ago, I noticed that my SNES console was aging particularly badly. I cleaned off all the remnants of fossilized Coke residue from the chassis with a wet washcloth, but the “moldy bread” look still remained. The top half of the console’s plastic body retained a uniformly nasty yellow-brown hue, while the bottom half flaunted its showroom shine — that native SNES gray that we all know and love. I soon realized that a much deeper mechanism was responsible for the aesthetic disfigurement of my beloved SNES than mere dirt and sugar.

To further complicate matters, I have another SNES unit that was obviously produced more recently than my original one, and that console shows no sign of aging whatsoever. Comparing the units and the way different parts of them had discolored led me to believe that there is something different about the two batches of plastics — the one for the top half of the SNES chassis and the one for the bottom, or the plastic for the old unit and plastic for the new — that made them age differently over time.

Immediately below are two photos I took of my actual SNES units. Notice the difference between the colors of the top and bottom halves of the plastic chassis on the older unit, and also how the newer unit shows no sign of discoloration at all.

My first SNES console (right) exhibits discoloration on the top half only.

The newer unit on the left, however, looks as good as new.

The top half and bottom half of my first SNES console, disassembled.

Notice that the underside is yellowed with the same uniformity as the top.

The Investigation Begins

Case yellowing effects aren’t limited to the Super Nintendo console. Many models of Apple Macintosh computers exhibit similar symptoms: their cases discolor heavily as they age, frustrating computer collectors everywhere. I had long heard that plastic discoloration had something to do with UV exposure, which made more sense for the Macs, but not so for the SNES. In the case of the SNES itself, the chassis was uniformly discolored on both the outside and the inside of the case, which means that it could not have been the work of light. With all this in mind, I set out to find what was causing these plastic yellowing effects, and if the yellowing on the SNES and the Macintosh cases were related.

After poking around the net, I found some forum threads where people seemed to have vague ideas about what was causing the yellowing. Suggestions and accusations from forum regulars like “Wash your hands!” or “It’s tobacco stains,” were usually returned with, “But I’m a clean guy!” and “I don’t smoke,” so the problem isn’t quite that simple. Other people weighing in on the issue seemed more knowledgeable and suggested that keeping computers away from windows and fluorescent lighting will help prevent discoloration. Sounds good to me, but why, exactly, would sunlight cause certain plastic to yellow while other plastics retained their original color?

While searching the forums, the most helpful hint I found regarding the SNES was this. Someone had asked Nintendo of America’s customer support about the issue, and this is how they responded:



Message(#6851-000101-5635\1015635) Hi! Thank you for contacting us. That’s an interesting question! For the Super NES, this is a normal condition and no cause for alarm. Cleaning or handling the system will have minimal impact to change or revive the original color. The Super NES, as well as our other systems, are made with a plastic containing flame-retardant chemicals to meet safety guidelines. Over time, the plastic will age and discolor both because of these chemicals as well as from the normal heat generated from the product or exposure to light. Because of the light color of the plastic of the SNES and NES, this discoloration is more easily seen than with other darker plastics such as on the N64 and the Nintendo GameCube. Thanks for your email!

Nintendo of America Inc.

Casey Ludwig Nintendo’s home page: http://www.nintendo.com/

Power Line (Automated Product Info): (425) 885-7529

Sounds pretty good to me, but is it true? While trying to get a more specific answer, I decided to write NOA myself to see what they said. This is what they responded:

Thanks for the e-mail. Unfortunately I don’t have an answer to your question. We’ve stopped servicing the Super NES many years ago, so our information is limited. I took a look at what we have, and nothing discusses housing discoloration. In addition I don’t have anyone I could refer you to that would be able to answer that question. If you need additional assistance, please contact our Consumer Service Department by calling 1-800-255-3700. Our representatives are available between 6:00 a.m. and 7:00 p.m. Pacific Time, seven days a week. Sincerely, Nintendo of America Inc.

Shane O’Neil

As you can read, the answer they sent me wasn’t nearly as helpful as the forum patron’s response. The only thing I learned from their reply is that people must not ask NOA support questions about discoloration very often if they don’t have a prepared answer for it.

[ Update: 01/17/2007 – Long ago, I tried to contact Nintendo of America’s PR Department about the plastic discoloration so I could get an official comment. This is the final reply I got from NOA today: “Sorry it has taken me a while to reply but I was unable to track someone down who could talk about the plastics chosen for the various Nintendo systems. The systems are shipped to the U.S. after they are assembled so it is decided out of the Nintendo corporate office in Japan.” Indeed, it is hard to track down the Japanese Super Nintendo plastics engineers who most likely didn’t even work directly for Nintendo. ]

When in Doubt, Consult an Expert

Unsatisfied with Nintendo’s answer, I decided to dig deeper. I contacted Dr. Rudolph D. Deanin, founder of the graduate program in Plastics Engineering at the University of Massachusetts, Lowell and director of the program for over thirty years. I told him everything I know about plastic chassis discoloration in both the Super Nintendo and Macintosh computers and asked what he thought might be causing it.

“The plastics most commonly used to make the structural cases for electronic equipment are polypropylene, impact styrene, and ABS,” replied Deanin. “These all tend to discolor and embrittle gradually when exposed to UV and/or heat. They become oxidized and develop conjugated unsaturation, which produces color. They crosslink or degrade, which causes brittleness.”

From looking at a stamp on the Super Nintendo’s plastic case, I learned that the case is composed of ABS, which is a rugged, durable plastic that is sadly more susceptible to discoloration and degradation from both UV and heat than the alternatives.

“There are other plastics which would be more stable,” Deanin continued, “but manufacturers avoid them because they are more expensive and/or more difficult to process.”

Instead of using more expensive plastics, manufactures put additives known as stabilizers, absorbers, or blockers into the plastic mixture to reduce the effects of degradation. They also get creative with their use of pigmentation.

“Since most discoloration is toward yellowing, some manufacturers add a little blue to neutralize the yellow,” Deanin said. “This gives a temporary reprieve, but eventually the yellow keeps growing and overpowers it anyway.”

The Best Answer Involves Chemistry

Deanin’s helpful response got me really curious. I wanted to know more about how exactly the whole plastic degradation process works, but he didn’t go into it in detail. For example, what exactly about degradation makes the plastic change color?

After a few days of research on the process though jargon-dense industry white papers and by lurking on plastics forums, I managed to piece together an answer. Unfortunately, most of what I found focused on the UV-degradation (light exposure) side of things, which is most applicable to the discoloration of Macintosh cases. But we can apply some of what we’ll learn to the SNES in a moment.

Most plastics typically reflect the majority of UV light that hits them. However, if there are trace elements of catalyst residues (chemicals used in manufacturing of the plastic), such as if the manufacturer doesn’t get the mixture quite right, then the residues present in the final plastic will absorb UV and drastically accelerate the degradation process. Exposure to UV light in this instance starts a process called photodegradation (through photooxidation), which takes place in parallel with thermal oxidation (from exposure to heat). Both processes break down the chemical structure of the plastic as certain parts of it combine with available oxygen. And once this process gets started, it feeds upon itself and starts a continual cycle of degradation. Interestingly enough, the disrupted plastic molecules that are produced by the photooxidation process absorb UV light themselves and re-emit it at a lower wavelength (in the visible range), which changes the perceived color of the plastic.

In the case of the SNES plastic, however, the trigger of the oxidation process is clearly not UV light, but simple and unavoidable exposure oxygen in the air over time, with heat possibly accelerating the process. Once the process is triggered, its effects cascade in a recursive cycle — as in the UV example above — eventually changing the physical nature of the plastic and its color. Visual proof that exposure to air is causing the SNES discoloration can be seen in the picture below:

A piece of my Super Nintendo’s case was chipped off accidentally at some point in the console’s recent history. Notice how the center of the case’s plastic — which hasn’t been exposed to air for very long — is still gray.

In The Name of Retardation

So think back. Those flame retardant chemicals that Nintendo mentioned are starting to sound like a plausible trigger for premature degradation in the SNES. If we presume that those flame retardant additives, if mixed in an improper amount, have a similar effect as the catalyst residues that are absorbing the UV light and heat and triggering the photodegradation process described above, then it could account for the discoloration effect we’ve seen. Deanin weighed in on the flame retardant issue only by saying that most retardants are harmless, but certain “aliphatic bromine compounds” are unstable to heat and UV, and should be avoided. Flame retardants unstable to heat! How ironic.

So Why the Two-Faced SNES?

Since two different batches of plastics had two different aging results (as illustrated in the top and bottom halves of my SNES, or the old and new SNES units), then there must have been a difference of additives between them. Perhaps in one of the production runs of plastic, they didn’t get the catalyst or flame retardant mixture quite right and more residues were left over in the top half’s plastic batch, thus causing it to degrade more rapidly over time. And by the time Nintendo produced the later runs of Super Nintendos, they had probably fixed the problems in the manufacturing process of their plastic, meaning that those later models aren’t as susceptible to oxidation as the earlier models are.

Some Super Nintendo consoles discolor only on the bottom half, some discolor only on the top half (like mine), and some on both sides evenly. Which side(s) get discolored is based only upon the luck of the draw â€” that is, which plastic batch was used to create each part of the plastic shell, and which manufacturing run the different halves of the case came from when the consoles were being assembled.

So, What Can I Do About It?

Now that you’ve heard all about plastic discoloration and its causes, you’re probably wondering what you can do to prevent or fix it. Unfortunately, the best answer is, “not much.” The only prevention tip Deanin had for me was this:

“A useful way to prevent UV discoloration is to put a UV-resistant plastic coating on top of the base plastic. This adds to the cost, but it definitely solves the problem. ”

Ok, so you can paint your old consoles with a UV-resistant coating, but that might not be a very attractive option to historical purists (if you care about that sort of thing). And applying an even coat without accidentally spraying connector ports, cartridge slots, and other electronics would be difficult without completely disassembling your unit and masking sensitive areas. So what can you do after the discoloration has taken place? Once, again, Deanin couldn’t offer many options.

“Paint it! The auto industry paints much of the plastic they use in cars. The paint industry could certainly design an optimum paint formulation for such a market.”

So, yeah, you could sand down your old consoles like an old car and paint them, which some people do already to make green and yellow “John Deere” Atari 2600s and black PlayStation 2-like Nintendo Entertainment Systems. But then the console becomes a “mod” and ceases to be faithful to the original design. Or you could try to match your console or computer’s original colors, but it might be difficult to pull off.

Despite all this general negativity, I have managed to put together a few tips and ideas about how to prevent and repair plastic discoloration.

Prevention Methods:

Apply a coat of UV protectant to all plastic surfaces on your console or computer. Keep your most prized collector pieces out of rooms with fluorescent lighting. Keep your units away from windows and sunlight because, like the fluorescent lighting, the UV exposure will drastically hasten their discoloration. Even indirect sunlight can do damage over time. Avoid placing your unit next to a heat source such as a radiator, air duct, or fireplace. Or in the fire. Keep your consoles and computers out of the attic. The repetitive, long-term cycles of extreme heat and extreme cool in most attics drastically speeds the degradation and breakdown of all plastics and rubbers. The heat does most of the damage, though. Do not keep your machines in a room where people smoke tobacco (wacky or otherwise). This doesn’t directly relate to internal chemical yellowing, but it can cause your console or computer to yellow for other reasons! Try not to breathe too heavily upon your console’s exterior.

Ok — this one’s a joke. For the ultimate in protection, seal your unit in a lead-lined, temperature-controlled, evacuated vault away from any radiation, visible or otherwise. But hey, what fun is that?

Repair & Restoration Methods:

Leave It Alone – In the world of antique furniture, collectors most often desire an aged look. Stripping chipped paint, polishing corroded copper, or filling in scratches considerably lessens the value of the item because such “defects” show how old it is. Collectors of the future may appreciate discolored plastic for that exact reason. Magic Erasers (melamine foam) – Great for surface dirt. Good for very light surface discoloration, but it will rub off painted logos and subtle textures like an abrasive. Sandpaper – Scrape your way to fresh plastic underneath. Not recommended for historical purists or console rights activists. Paint – Cover up that ugly yellowed plastic and turn your SNES into a shiny ode to Heinz ketchup. Chlorine Bleach – I’ve had very limited success with letting bleach sit on Macintosh cases. When it does work, it’s difficult to get a uniform effect unless you can soak the whole piece in bleach equally. This probably damages the structure of the plastic and might cause another type of yellowing — so beware! Acetone – Many people have mentioned acetone as a good way to clean off some plastic yellowing. The only reason this might work is because most plastics dissolve in acetone. If you use this method, be aware that you’re doing damage to the plastic — you’re wiping it away. Hydrogen Peroxide (Added 02/22/2009) – In the last year or so, a new method of reversing yellowing has cropped up in some corners of the net (dubbed “Retr0bright”) that involves hydrogen peroxide in high concentrations (10%-15%) and exposure to UV light. If other people’s experiences are any indication, this process seems to work if applied properly. But remember that even if discoloration is reduced, your cases will yellow again some day unless coated with an oxygen-proof sealant after treatment. Be warned: hydrogen peroxide in high concentrations is very dangerous (it can blind you and burn your skin), and this method can cause permanent damage to plastic if done improperly. Despite numerous demonstrations of this technique and a seemingly sound theory behind it, the jury is still out on whether this method harms plastics or color pigmentation in the long-term. Be that as it may, this technique is currently the best, least-destructive method we have of reducing yellowing in ABS plastics.

The “Magic” in Magic Erasers I have recently overheard a number of collectors talking about using “Mr. Clean Magic Erasers” to clean their computer cases. Magic Erasers are incredibly effective at removing surface dirt, smudges, or cigarette smoke film (when it’s not chemically bonded to the plastic). But using them to combat intrinsic case yellowing is another story all together. I have recently overheard a number of collectors talking about using “Mr. Clean Magic Erasers” to clean their computer cases. Magic Erasers are incredibly effective at removing surface dirt, smudges, or cigarette smoke film (when it’s not chemically bonded to the plastic). But using them to combat intrinsic case yellowing is another story all together. Magic Erasers are made entirely of a substance called melamine, which is lightweight, heat resistant organic compound which has, in the case of Magic Erasers, been extruded into a microporous foam. Until someone discovered its cleaning properties, melamine was used primarily as a flame resistant sound-proofing material and as an ingredient in resin laminates. Melamine foam has a microscopic open-ended bubble structure that, with the aid of water, finds its way into previously impossible-to-clean cracks, crevices, and textures. Despite their amazing cleaning potential, Magic Erasers are no more than fancy abrasive pads, complete with all the drawbacks that entails. Which means that you should exercise caution while using Magic Erasers or other melamine foam products. Magic Erasers essentially act like extremely fine-grade sandpaper that will wear away any surface over time with repeated scrubbings. It happens so slowly, however, and on such a small scale that its effect is hard to notice at first. But if you keep rubbing and rubbing, you’ll wear more and more of what you’re rubbing away. Permanently. Magic Erasers are capable of removing discolored plastic to a limited extent, but you’ll have to scrub very hard and you’ll lose surface texture in the process. I tried scrubbing for about ten minutes on both SNES and Mac LC III cases with melamine foam, but the results were unsatisfactory due to the smoothing of the cases and the paltry reduction in yellowing. If you’re into abrasives like that, you might as well use sandpaper for a quicker result (but you’ll regret it). Save the Magic Erasers for surface dirt only.

A Gallery of Dysfunctional Plastics

Finally, with all that other stuff out of the way, I thought I’d show you some more pictures of plastic discoloration. They range from SNES cartridges to video monitors.

Enjoy, and help keep plastics clean and beautiful.

SNES cartridges are not immune to the vagaries of plastic discoloration.

Like the SNES unit itself, sometimes two halves of a cartridge case

will age differently due to different manufacturing runs.

UV at Work: This computer sat in sunlight for years with a monitor connected.

Notice how the monitor connector shielded some of the plastic from

discoloration, preserving the original gray color only in that spot.

Here’s one where a monitor sat on top of a Mac for years, shading

the plastic underneath from exposure to sunlight.

This poor Apple IIe Platinum has been the victim of discoloration too.

Yes, most of my equipment looks this bad! This discoloration is the result of this

monitor sitting in a room with fluorescent lighting as the only light source for a very

long time. The two parts of the monitor were originally the same light gray color.

[ Update: 06/26/2008 – Si vous voulez lire l’article en FranÃ§ais, vous trouverez une traduction ici. (As of 03/08/2010, this French translation link is dead.) ]