If you own a Super Nintendo, a NES, a Dreamcast or an old Amiga computer, you’ve probably noticed this frustrating phenomenon: the original light-grey or white plastic has turned yellow, sometimes even brown in the most extreme cases. This yellowing, which mainly affects consoles and computers from the 1980s and 1990s, is no accident. Here’s why it happens — and what people have tried to do about it.

The culprit: brominated flame retardants

The main offenders are brominated flame retardants added to the plastic. To understand why, we need to go back to the safety standards of the time.

In the 80s and 90s, manufacturers had to comply with strict fire-safety regulations. To ensure their consoles didn’t catch fire too quickly in case of an electrical issue, they added bromine (a chemical compound) to the ABS plastic (Acrylonitrile Butadiene Styrene) used for the shells. Nintendo officially confirmed that the Super NES — like their other systems — was made from plastic containing flame-retardant chemicals to meet safety requirements.

The problem? When this bromine is exposed to UV light (from sunlight or even artificial light) and oxygen in the air, it oxidises. This chemical reaction gradually turns the plastic yellow.

Why does it yellow even in the dark?

A surprising fact: some consoles yellow even when stored in sealed boxes! Some owners found their brand-new Super Nintendo already slightly yellowed despite being kept untouched in its packaging for years.

Why? Oxygen alone is enough to trigger the process — UV light simply accelerates it dramatically. It’s a bit like metal rusting: it eventually happens even when stored away.

Why do some parts yellow more than others?

One of the most frustrating mysteries: on the same Super Nintendo, the top shell can turn very yellow while the bottom half remains perfectly grey. Several explanations exist:

Different production batches: Only certain batches had this issue, and later SNES models no longer suffered from it. Nintendo seems to have adjusted the flame-retardant dosage during production. The top and bottom of your console may simply come from two different batches with slightly different compositions.

Uneven exposure: The top of the console is much more exposed to light than the bottom. More UV = more yellowing.

Cigarette smoke?: Contrary to popular belief, cigarette smoke is often wrongly blamed for yellowing. It can leave a yellowish layer of dirt (which can be cleaned), but true yellowing comes from the plastic chemistry itself.

How does it work exactly?

Without diving too far into chemistry: ABS plastic is made of three components (Acrylonitrile, Butadiene, Styrene). When UV light and oxygen react with bromine-loaded plastic, they create molecules that absorb blue light. As a result, our eyes see yellow-orange.

The miracle solution? Retrobright

Since the mid-2000s, enthusiasts have been using a technique called Retrobright to reverse yellowing. The original discovery came in March 2008 from the CBM museum in Wuppertal, Germany, which found that immersing plastic pieces in a hydrogen-peroxide solution for several days could partly reverse the process.

The principle

Retrobright uses hydrogen peroxide, a small amount of TAED as a catalyst (commonly found in laundry boosters), and a UV light source. The mixture is applied to the plastic, which is then exposed to UV light (sunlight or a UV lamp). The peroxide breaks the chemical bonds responsible for the yellow colour.

What methods exist?

There are indeed several:

1. Immersion method: Using a mixture of 3% hydrogen peroxide and distilled water, then letting the pieces sit in the sun for around 8 hours.

2. Gel method: Creating a thick gel using peroxide and a thickener (such as xanthan gum), then applying it with a brush. It’s more economical because it uses less product.

3. Vapor method (the newest): Discovered by Simon Lock, this method uses hydrogen-peroxide vapour. A small amount of food-grade peroxide is placed inside an airtight container along with the plastic piece. The advantage? Far less product required and more even results.

Bigkam shares his solution (2022 video)

Don’t try this at home!

It’s dangerous! Concentrated hydrogen peroxide can cause chemical burns. These operations are done by experienced and properly equipped hobbyists.

Variable results: It works better on some plastics than others. Game Boys, NES consoles and controllers generally react very well. Grey consoles can be trickier.

The big issue: it’s not permanent, and side effects appear

Many “Retrobrighters” noticed their consoles slowly yellowed again a few months after treatment, even though they were stored safely, wrapped, and protected from light.

Yellowing returns after six months to a year and a half — even without direct light exposure. Why? Because Retrobright doesn’t repair the plastic; it only “bleaches” the surface. The bromine is still inside the plastic and keeps reacting.

Some hobbyists recommend applying a protective varnish after treatment to slow down re-oxidation, but nobody really knows if this works long-term.

Does Retrobright weaken the plastic?

This is a debated topic. Some argue that it doesn’t weaken plastic because the reaction only occurs on the surface. Others are more cautious. What’s certain is that yellowed plastic is already weakened by oxidation — which is why old consoles often crack during disassembly.

A recent article on Time Extension also reports negative experiences, notably on a Dreamcast.

How to prevent yellowing?

The best strategy is prevention:

• Avoid direct light: Keep consoles away from windows or strong lamps
• Stable temperature: Avoid heat sources and sudden temperature changes
• Smart storage: A cool, dry, dark area is ideal
• Airtight packaging: Some use airtight bags with desiccant packs

But let’s be honest: even with all these precautions, some consoles will still yellow. It’s in their chemical DNA.

Conclusion

Yellowing in old consoles is the result of an unfortunate combination: the fire-safety requirements of the 80s and 90s (which required brominated flame retardants) and the chemistry of ABS plastic exposed to UV light and oxygen. It’s a natural, nearly unavoidable process.

Retrobright can give your consoles a second youth, but it’s temporary and may cause irreversible side effects. You’ll need to be cautious if you decide to try it. For some collectors, the yellowing is even part of the charm and history of the console.

In the end, whether you choose to treat your consoles or embrace their aged look, the most important thing is that they still work — and keep bringing back magical retrogaming memories!

As for us at Recalbox, we’ve found our own solution: we made a black RecalTower!!!

Sources

• Vintage Computing & Gaming – "Why Super Nintendos Lose Their Color"
• The Old School Game Vault – "Why Video Games and Consoles Turn Yellow" (2025)
• RetroGamingStores.com – "Why Does the Super Nintendo Turn Yellow?"
• RetroJimmy – "The Curious Case of the Yellowing Super Nintendo" (2025)
• Nintendo Life Forums – Discussion on SNES yellowing (2012)
• Wikipedia – "Retrobright" (January 2025)
• Medium – Thomas Fuchs, "How to retrobright old yellowed plastic" (2021)
• Retrocomputing Stack Exchange – "Definitive guide to retrobright?"
• Hackaday – "Plastic Cleanup Via Retrobrighting" (2020)
• RetroRGB – "New RetroBrite Method Discovered | The Vapor Method" (2022)
• Obligement.fr – "Utilisation du Retr0Bright"
• Darius-Saturn.com – Forum on yellowing and Retrobright (2020)
• LoisirCreatif.net – "Le retrobright, anti jaunissement des consoles" (2020)
• VoxGaming.fr – "Retrobright, le tuto ultra complet"
• Jonathan Dupré – "Mon retour sur le Retr0bright" (2022)
• Forums Gamopat – Discussions on Retrobright (2019–2021)
• HFS Play Forum – "RetroBrite: Donnez un coup de neuf à vos plastiques!" (2015)