How to Clean Old, Yellowed Plastic on Retro Computers and Game Systems

Ever notice how your old gadgets have turned an ugly yellow color since you bought them? Old Macs, Commodores, Nintendo systems, and other machines look dreadful 30 years later—but there is a way to brighten them up again.

Why Old Plastic Turns Yellow (and How You Can Make It White Again)

This yellowing happens thanks to a flame retardant called bromine in those old ABS plastics. When exposed to UV light, those bromine molecules can destabilize and leech through to the surface, causing the plastic to turn yellow (or even brown if left long enough). Modern plastics have improved the chemistry so this process doesn’t happen, but those old machines from the 80s aren’t so lucky.

Different retro machines will yellow at different rates than others, even from the same line of products. Your Super Nintendo may be much yellower than your friend’s, just because they were from different batches of plastic. Here’s what’s even weirder: sometimes, two pieces of plastic in the same machine can be different levels of yellow, like a meth head with half a denture set. The Super Nintendo we’ll be using as our example today, seen below, has a much yellower base than top.

The cartridge slot shows the original SNES color. You can see the surrounding top case has yellowed some, and the bottom case has yellowed a lot.

A few years ago, some enterprising and chemistry-savvy forum users discovered that hydrogen peroxide could help remove these free bromides from the plastic, restoring the original white color. It isn’t permanent, unfortunately, since there are still free bromides deep in the plastic that can re-surface after another few years. In addition, some people think the process makes those plastics more brittle and fragile. But if you’re willing to put up with those annoyances, it’s a great way to make your retro gadgets display-worthy once again. They created a recipe of ingredients and dubbed the formula Retr0bright. You can read more about it at the original Retr0bright page, and more about the science in this great blog post on the subject.

There are plenty of guides out there, but after trying it a few times ourselves, we found that—while most guides are quite decent (including the one linked above, and this fantastic video from The 8-Bit Guy on YouTube)—they gloss over some important details to make the process as smooth as possible. So today, we’ll show you how to de-yellow those old gadgets, using a super cheap solution you can buy in a bottle.

What You Need

Since Retr0bright’s creation, many people have come up with different methods for Retr0brighting their systems, with different advantages and disadvantages. The original Retr0bright recipe called for 10% hydrogen peroxide solution mixed with a few other ingredients to give it a more creamy consistency. But after a while, some people found that this “recipe” was unnecessary: you can already buy a creamy hydrogen peroxide solution in the form of hair developer (the 8-Bit Guy calls it “Retr0bright in a bottle”). Head to any beauty supply store and ask for 40 Volume Creme Developer and you’re in business We’re using this $3 bottle by Salon Care from Sally Beauty.

Note: Some people recommend submerging your plastic in a tub of 10% to 15% hydrogen peroxide liquid instead of using the cream (no higher, or you’ll increase the chance of blooming and streaking). Granted, this is easier (and a bit less likely to cause streaking), but it’s more dangerous, not to mention expensive. Plus, it doesn’t allow you much control, as everything will be covered—you can’t avoid labels or other lettering. As long as you follow our instructions to the letter, the cream should work well, with minimal streaking.

Apart from your Retr0bright of choice, you only need a few other things:

  • Rubber gloves: I highly recommend some sort of hand covering, since you don’t really want to get this stuff on your skin, as it’ll give you a nice chemical burn. You can get some from the beauty supply store as well if you don’t have them already.
  • Safety goggles: You should absolutely wear some sort of protective eye covering, since you definitely don’t want to get this stuff in your eyes, as it can blind you. (Seriously, do not skip these!)
  • A paintbrush or tint brush: You’ll also want a brush to apply the cream. An old paintbrush will work, but you can also grab a tint brush for a buck or two along with the developer at the beauty supply store—that’s what I did.
  • Cling wrap: You’ll need this to prevent the cream from evaporating, which will help you get an even result.
  • Rubbing alcohol: You’ll want to clean the plastic before you Retr0bright it. Relatively clean devices will probably just need water and a rag, but denatured or isopropyl alcohol is rather useful for getting some of those tougher scuffs and dirt marks off.
  • A screwdriver (and any other necessary tools): Lastly, you’ll likely need a screwdriver to take apart your gadget, along with any other necessary tools (some Nintendo systems require a special bit to get it open, for example). I also use a magnetic screw tray to keep all those little screws organized, but that’s optional.
  • A UV light bulb (optional): If you have the space, and don’t want to leave it out in the sun (which requires more attention to avoid streaking), you can use a UV light in a separate room. I didn’t opt for this method myself, but I’ve heard good things about it.

Once you’ve got everything in one place, read through the instructions below very carefully before you get started.

Step One: Disassemble Your Hardware

If at all possible, we highly recommend disassembling the device in question before you start cleaning and Retr0brighting. Ideally, you will break it down to just the plastic parts you want to clean, with all the metal pieces and circuitry set aside. This will make the cleaning much easier (since you’ll be able to hose it off), and avoid any problems with the Retr0bright harming the internals.

This process will differ depending on what you’re taking apart, so hit up YouTube for a “teardown” video of your specific gadget—chances are, there are probably a few out there. Set aside the internals and make sure you don’t lose any of the screws (again, this is where that magnetic screw tray comes in handy). Once you have just the plastic pieces left over, you’re ready to start cleaning.

Step Two: Clean the Plastic Thoroughly

Again, this step will differ a bit depending on what you’re cleaning, but in general, I’ve found that a thorough cleaning of the plastic contains two or three steps.

First, clean any dust, hair, and dirt off the plastic with plain ol’ water. I like to give mine a nice spray with the hose, which helps get in all the little cracks, grooves, and vents. Dry it off with a rag when you’re done. (You can also wipe it down with a wet rag if you’d prefer not to spray it with the hose—like if there are some internals you couldn’t dismantle).

Once the plastic is dry, you’ll probably find that there is still a lot of grime on it, not to mention scuff marks and other blemishes. To clean that off, I recommend taking a rag and some denatured or isopropyl alcohol and putting some elbow grease into it. A lot of the grime and scuffs should come right off, while others may need some serious rubbing. Make sure you stay away from lettering and other painted-on graphics, as the alcohol will damage them! (For example, the red lettering on the front of an original Nintendo system will rub right off with alcohol.)

You may find, even after your arm is sore from rubbing with alcohol, that some scuff marks don’t come off. In this case, I often turn to the Mr. Clean Magic Eraser. It will almost always get those scuff marks out, but note that it is an abrasive—which means it may remove some texture and finish from the gadget. If that worries you, you can skip this step. Myself, I’d rather risk a slightly shinier spot on the plastic than look at black scuff marks. It’s up to you. Just be sure to start lightly, and rub harder only if you need to.

Step Three: Apply the Retr0bright

Once your device is clean of all other dirt and grime, it’s time to turn our attention to those pesky Bromides. Enter Retr0bright. You’ll need ample sunlight for this part of the process, so I recommend getting started early in the morning so you can get as much time in the sun as possible—otherwise, you may have to do it a second day. However, you may want to do this first part in your garage or another enclosed area, so the breeze doesn’t blow the cling wrap around while you’re trying to work.

First, I like to cover up any labels with Scotch tape to protect them (especially the paper ones, which will disintegrate when soaking in liquid or cream). If there are any painted-on letters, you may want to avoid those pieces, as the Retr0bright can fade or damage them. In general, I recommend only Retr0brighting the very light plastic pieces—smaller buttons or darker colored plastics are probably fine as-is.

Next, after putting on your gloves and safety goggles, lay out your cling wrap—you may need multiple pieces if your gadget is big, since it needs to cover it completely—and pour some of the Retr0bright on the cling wrap. Spread it around with your brush, then pour the Retr0bright on the plastic. Brush it around as well. Don’t be afraid to use a lot of cream, as you want to liberally cover every inch of the yellowed plastic. (You can even do the inside, if it’s yellowed, though that may not be necessary on some parts.)

Then, put the plastic piece on the cling wrap and wrap it up. The idea is to seal it up nice so you can keep the Retr0bright from evaporating, which will cause streaking. Again, full plastic wrap coverage is important.

Repeat this process with your other plastic pieces.

Step Four: Leave It In the Sun, Rotate and Re-Apply Regularly

Once your plastic parts are all wrapped up, put them out in direct sunlight (or under your UV bulb). UV exposure may have caused this mess, but it’s also the secret ingredient that will help us clean it up. You’ll want to leave it out there for a few hours, so find a spot that gets direct sunlight for most of the day if you can.

Here’s the important part: try to work out as many of the air bubbles as you can and spread the cream evenly. Then, every half hour, rotate the pieces 90 degrees, and (with your gloves on) massage the Retr0bright around the plastic from outside the cling wrap. This keeps it moving around and stops air bubbles from staying in one place for too long, which is how you get a blotchy, streaky finish. If you don’t do this, you will get bad results!

Lastly, it’s best to rinse the parts off (see the next step) and re-apply a new coat after the creme starts to look more like a foam, usually after two to three hours depending on how hot and sunny it is. This keeps the Retr0bright from drying out and causing blooming/streaking.

It sounds tedious, but it’s well worth the effort. After six to nine hours, you should see a noticeable improvement, though you may be able to get by with less if your plastic was only a little yellow.

Step Five: Rinse It Off, and Repeat If Necessary

Once the plastic looks like it’s sparkly white again (or if you run out of sunlight), unwrap the pieces and rinse them off, either with a hose or in a sink (far away from food). You will likely need to rub excess Retr0bright off the plastic, since it’ll be pretty thick and foamy and stuck on there, so wear your gloves and give it a good, long massage under the water. Be sure to get in all the tiny cracks and crevices, as the Retr0bright will definitely get stuck in those areas and you’ll need to scrub it out.

You can dry the plastic off with a rag if you want now, or leave it to drip dry. Once it’s dry, you should find that it looks much better than before!

If, however, you find that it’s still yellower than you would like, feel free to repeat the process the next day. Some really yellow plastics may need a few days in the sun to whiten up. My Super Nintendo, for example, looked better after seven hours:

You can see the top case now matches the cartridge slot, but while the bottom has improved, it still has a way to go.

But the bottom piece needed a whopping 24 hours in the sun to really get back to where it should be. It was a lot of work, and I did get some blotchiness on the bottom from not re-applying often enough. It isn’t perfect, but overall it looks way better than it did before:

Just like 1992!

So just keep doing it until you get the results you want.


Once you’ve thoroughly rinsed and dried your plastic, and you’re happy with the results, you’re all done! Re-assemble your gadget and it’ll be just like the day you bought it, fresh and white from the factory. Remember, it will re-yellow after some time—even if it’s kept in a dark area, since those free bromides are already loose deep in the plastic—but you can always go through this process again if it gets too yellow for you.

Whitson Gordon is is the editor-in-chief of How-To Geek. He is also a Windows user, PC builder, metalhead, chopstick-using potato chip eater, and Midwest-to-Southern California transplant. You can follow his nerdy exploits on Twitter and Facebook.