Many older Game Boy consoles exhibit noticeable discolouration, a phenomenon widely referred to as “yellowing.” The original DMG-01 Game Boy, released by Nintendo in 1989 with a distinctive greyish, off-white casing, frequently develops a yellow or beige hue over time. However, this issue is not limited solely to the original DMG model. The later Game Boy Pocket and Game Boy Color, as well as the brightly coloured “Play It Loud” series, are also susceptible to similar colour changes. Unlike the DMG-01, these coloured models typically experience darkening or a muted appearance rather than obvious yellowing, though the visual effect can still be pronounced.

Discolouration is not unique to Game Boys; it is characteristic of plastics used widely across electronic devices from the 1980s and 1990s, such as computers, telephones, and gaming consoles. While this phenomenon is often mistaken for surface dirt or grime, the actual cause of discolouration lies deeper within the material itself. It is primarily due to chemical reactions occurring inside the plastic, accelerated significantly by environmental factors such as ultraviolet (UV) radiation, heat, and humidity.

The extent of discolouration varies significantly based on individual exposure. Consoles stored in sunny, humid environments tend to discolour more rapidly and dramatically than those kept in darker, cooler locations. Even identical units produced simultaneously can differ greatly in appearance decades later, highlighting the importance of proper storage conditions.

Why Does Plastic Change Colour? 

The fundamental cause of discolouration in plastics, including those used in Game Boy consoles, lies in their chemical composition. Manufacturers commonly used Acrylonitrile Butadiene Styrene, or ABS plastic, during the 1980s and 1990s due to its desirable properties, including high impact resistance and durability. However, to meet safety regulations of the era, particularly fire-resistance standards, these plastics often included brominated flame retardants. Although effective for improving safety, these chemical additives made the plastics inherently prone to long-term instability.

At a molecular level, discolouration results primarily from oxidation—a chemical reaction between the plastic’s brominated compounds and atmospheric oxygen. Bromine molecules migrate slowly to the surface of the plastic over many years, reacting with oxygen to form visible discolouration. This chemical change is notably accelerated by ultraviolet (UV) radiation from sunlight, which provides energy to break chemical bonds and hastens the oxidation process. This explains why devices left exposed to direct sunlight often show severe yellowing or other colour changes after prolonged exposure.

In addition to UV exposure, heat significantly accelerates discolouration, as higher temperatures increase molecular activity within plastics, speeding up the migration and oxidation of bromine. Humidity also exacerbates oxidation, providing moisture that facilitates chemical reactions. Plastics stored in attics, sheds, or humid climates typically show greater levels of discolouration compared to devices stored in cool, dry places.

While surface dirt or grime can exaggerate or mimic the appearance of discolouration, true chemical oxidation is a permanent, molecular-level alteration. Surface contamination is typically removable through careful cleaning, whereas chemically oxidised plastic requires more specialised restoration techniques, often involving chemical treatment rather than simple surface cleaning.

What Is Retrobrighting?

Retrobrighting emerged as a popular chemical restoration process specifically designed to reverse or significantly reduce the visible effects of plastic oxidation and discolouration. Originally developed by enthusiasts within vintage computing and gaming communities, retrobrighting utilises hydrogen peroxide in combination with ultraviolet (UV) light to chemically alter the oxidised surface layer of affected plastics, restoring their original appearance.

Unlike traditional cleaning methods that merely remove surface dirt or contaminants, retrobrighting targets the oxidised layer itself. During the retrobrighting process, hydrogen peroxide acts as an oxidising agent, breaking down brominated compounds that have migrated to the plastic surface. Exposure to UV radiation—whether from natural sunlight or artificial UV lamps—is essential for activating this chemical reaction, facilitating the breakdown and removal of the discoloured surface layer.

The popularity of retrobrighting among collectors and restorers arises from its effectiveness in returning visibly yellowed or otherwise discoloured plastic to a condition closely resembling its original appearance. However, the practice is not without controversy. Advocates argue that retrobrighting significantly improves aesthetics and can enhance the perceived value of vintage electronics. Critics, however, caution about potential drawbacks, including weakening the plastic, inconsistent results, and a lack of permanence, as yellowing may return over time.

Due to variations in outcomes, several distinct retrobrighting methods have been developed, each with unique advantages and limitations. Enthusiasts can choose from liquid peroxide immersion baths, targeted gel-based applications, or the newer hydrogen peroxide vapour method. While each method differs in application complexity, consistency, and risks, all fundamentally rely on the same chemical principles.

Methods of Retrobrighting

The hydrogen peroxide bath method involves fully immersing plastic components in a dilute hydrogen peroxide solution, typically between 6% and 12% concentration. Once submerged, items are exposed to UV radiation, usually sunlight, but occasionally UV lamps for controlled indoor treatment. The advantage of immersion baths is uniform exposure, typically leading to even results. However, they require significant preparation, including appropriately sized UV-transparent containers and safety precautions due to chemical handling. Immersion times vary widely, from several hours to multiple days, depending on the severity of discolouration.

When immersion isn’t feasible, collectors often utilise a gel-based approach. Hydrogen peroxide is combined with thickening agents such as xanthan gum or hair-bleaching cream to form a viscous gel, allowing precise, targeted application onto discoloured surfaces. Once applied, the treated plastic is exposed to UV radiation similarly to immersion methods. Although highly flexible, enabling treatment of larger or complex objects, gel applications carry risks of uneven coverage and streaking. Continuous monitoring and occasional reapplication are often necessary for consistent results.

The hydrogen peroxide vapour method has gained popularity more recently due to its unique approach. Plastics undergoing treatment are placed in sealed containers above shallow trays of hydrogen peroxide, eliminating direct liquid contact. When exposed to UV radiation, vapours released from the peroxide evenly treat surfaces. This method reduces risks associated with streaking or uneven gel application, although treatment durations can be longer—typically one to two days. Users must ensure proper sealing of containers and continuous UV exposure throughout the process for optimal results.

Across all methods, successful retrobrighting relies heavily on meticulous care, careful preparation, and continuous monitoring. Consistency of UV exposure is crucial; uneven exposure can result in patchy or unnatural-looking restorations. Protective measures—including gloves, eye protection, and adequate ventilation—are necessary for safe chemical handling. Additionally, testing treatments on inconspicuous or spare parts is recommended to avoid accidental damage, especially to labels or other sensitive areas.

Choosing a retrobrighting method largely depends on practical considerations like the plastic’s original condition, available resources, personal experience, and willingness to manage chemical risks. Each method offers distinct trade-offs between convenience, consistency, and safety, enabling collectors to select approaches that best meet their specific restoration goals.

How Effective Is Retrobrighting?

Retrobrighting can produce impressive visual results, but its effectiveness varies considerably depending on several factors, such as the severity of the discolouration, the method chosen, the plastic’s original formulation, and the treatment duration. Generally, mild to moderate yellowing responds best to retrobrighting, resulting in near-original appearance after a single treatment. However, items with severe or deeply set discolouration often require multiple treatments or extended exposure to hydrogen peroxide solutions to achieve similar results. Even then, complete restoration isn’t guaranteed, and subtle colour variations may persist.

While retrobrighting effectively removes the visible oxidised layer of plastic, it does not resolve the underlying chemical instability responsible for discolouration. Consequently, treated plastics may gradually revert to a yellowed state over time, particularly if exposed again to environmental factors such as UV light, heat, or humidity. The duration of retrobrighting results varies greatly between individual cases; some collectors report that restored plastics remain visibly improved for several years, whereas others see noticeable yellowing return within months.

Different retrobrighting methods also produce varying degrees of success. Immersion baths generally yield the most consistent results due to uniform exposure. However, this method requires large volumes of hydrogen peroxide and appropriate containers, which may not always be practical. Gel-based treatments are simpler to apply and ideal for larger or irregularly shaped objects, but they can result in uneven restoration if not applied meticulously. The hydrogen peroxide vapour method, although slower, offers consistent, streak-free results by evenly treating plastic surfaces without direct liquid contact, reducing some common issues found with gels.

Ultimately, the condition of the plastic prior to treatment heavily influences retrobrighting outcomes. Highly brittle or severely deteriorated plastics often respond poorly, sometimes becoming structurally compromised or appearing artificially bleached after treatment. Additionally, plastic formulations differ slightly across manufacturers and production batches, meaning two seemingly identical items may respond differently to the same retrobrighting technique.

Given these complexities, managing expectations is crucial for collectors considering retrobrighting. Although significant cosmetic improvements are achievable, perfect restoration is not always possible. Success relies on careful method selection, diligent monitoring during treatment, and an understanding of inherent limitations in the retrobrighting process.

Potential Risks & Controversies

Despite retrobrighting’s popularity, the practice remains controversial among retro electronics collectors and preservationists. The primary concern revolves around the long-term structural integrity of treated plastics. Although empirical data is limited, many collectors report anecdotal evidence of increased brittleness, cracking, or structural weakness following repeated or overly aggressive retrobrighting treatments. The chemical interaction between hydrogen peroxide and plastic, particularly when accelerated by UV exposure, may weaken the polymer structure at a microscopic level. This can reduce durability, potentially shortening the lifespan of the treated plastic.

Another frequently cited issue is the potential for uneven or unnatural-looking results. While carefully executed treatments usually produce aesthetically pleasing outcomes, rushed or improperly monitored procedures can leave plastics with streaks, blotches, or unnatural “bleached” appearances. Such uneven outcomes can be difficult or impossible to correct, reducing the item’s visual appeal and, potentially, its value.

Retrobrighting can also negatively impact serial number labels, original stickers, and other adhesive markings. Hydrogen peroxide solutions and prolonged UV exposure may cause labels to fade, peel, or degrade significantly. In contrast, printed or moulded text embedded directly into plastic surfaces typically remains unaffected. Nevertheless, careful precautions—such as covering labels or temporarily removing sensitive stickers—are advisable to avoid damage.

Within the collector community, there is also debate over authenticity. Purists often argue that chemically altering original plastics diminishes the historical authenticity and collectible value of vintage electronics. For these collectors, natural discolouration represents part of an item’s history, character, and appeal. Restored devices, particularly if visibly altered, may not appeal to buyers or collectors seeking authenticity over cosmetic appearance.

These controversies underline the importance of careful consideration before retrobrighting. Collectors and restorers must weigh potential aesthetic improvements against risks to the integrity, authenticity, and long-term preservation of their devices.

Alternatives to Retrobrighting

For collectors hesitant to adopt retrobrighting, several alternative methods can effectively manage or minimise visible discolouration without chemical treatments. Simple yet thorough cleaning often delivers surprisingly positive results, especially when apparent discolouration is primarily surface-level dirt or grime accumulation. Washing plastic shells carefully with warm soapy water and soft brushes can significantly enhance appearance by removing layers of grime accumulated over decades. For stubborn residues, applying isopropyl alcohol (IPA), especially the 99% variety, provides effective spot-cleaning without harming the plastic surface. These cleaning methods offer a safer, less invasive way to refresh the appearance of vintage consoles.

In situations where cleaning alone isn’t sufficient, re-shelling represents another viable alternative. Re-shelling involves replacing the original, heavily discoloured or damaged shell with either an original replacement or a high-quality aftermarket reproduction shell. While original shells offer maximum authenticity, high-quality reproductions can closely mimic the appearance and texture of the original, providing a fresh aesthetic without chemical treatment risks. This approach is particularly appealing when original shells have become brittle, structurally compromised, or severely discoloured beyond practical restoration. Re-shelling also eliminates concerns about chemical weakening or uneven retrobrighting results, ensuring a visually consistent finish.

Preventative maintenance also plays an essential role in managing discolouration. Proper storage significantly slows further deterioration of plastics. Collectors can preserve current conditions by storing devices away from direct sunlight, in cool and dry environments with stable temperatures. Protective measures, such as using UV-resistant display cabinets, covers, or specially designed console cases, offer practical protection against environmental factors, helping maintain the existing condition and appearance of collectible items.

Lastly, some collectors embrace natural ageing and discolouration as part of an item’s historical authenticity. A carefully maintained but naturally aged console holds significant appeal for many enthusiasts, who view discolouration as evidence of the console’s age, character, and history. This approach encourages appreciation for vintage electronics as genuine historical objects, embracing ageing as part of the device’s intrinsic value rather than a flaw needing correction.

By carefully assessing priorities—whether aesthetics, preservation, authenticity, or structural integrity—collectors can select methods aligned closely with their personal collecting goals, ensuring the long-term enjoyment and value of their vintage devices.

Useful Links

Understanding Plastic Discolouration

• Why do old gaming consoles go yellow? - Retro32

• Why Does Old Plastic Turn Yellow? (Video Explanation)

Retrobrighting Methods and Guides

• Retrobrite - Wikipedia

• Retr0bright: How to Turn a Yellow Gameboy White Again - Instructables

• DIY Retrobright Whitening Solution - Instructables

• Definitive Guide to Retrobright - Retrocomputing Stack Exchange

• How to Retrobright Old Yellowed Plastic - Medium

Hydrogen Peroxide Vapour Method

• Retrobrite Vapor Method - Rob’s Nerd Shiz

• Tutorial: Retr0Brite VAPOR Method (Video Guide)

Alternative Preservation Methods

• How to Clean Yellowed Plastic - The Spruce

• Why Video Games & Consoles Turn Yellow - The Old School Game Vault