Retrobright is a chemical mixture used to remove yellowing from acrylonitrile butadiene styrene plastic computer and electronics cases, including computers that were manufactured by Commodore and Apple in the 1980s and 1990s, and various video game consoles and cartridges. The original meaning has been expanded, so now "retrobright" often refers to indicate any H2O2 based process used to remove yellowing from ABS plastics. The usage has also expanded to other retro restoration applications, such as classic and collectible sneaker restoration. Yellowing is caused by both bromine and exposure to ultraviolet light. Many of the ABS plastics used in consumer electronics devices are typically "brominated"—combined with bromine as a fire retardant—to meet fire safety standards. The method of reversing the yellow discoloration was first discovered in 2007 in a German retrocomputing forum, before spreading to an English blog where it was further detailed. The process has been continually refined since. There is still some debate over the long-term effectiveness of this technique. Some have discovered the yellowing reappears, and there is discussion of factors that may result in this happening. There are also some concerns that the process weakens the plastic.
Composition
Retr0bright consists of hydrogen peroxide, a small amount of the "active oxygen" laundry booster TAED as a catalyst, and a UV lamp. The optimum mixture and conditions for reversing yellowing of plastics:
Approximately 1 ml per 3 liters of tetraacetylethylenediamine -based laundry booster.
A source of ultraviolet light, from sunlight or a UV lamp. However, the YouTube channel "Modern Classic" demonstrated that exposure under UV-minimized fluorescent lighting for a period of twenty-four hours will give similar results.
Xanthan gum or arrowroot can be added to the mixture, creating an easier-to-apply gel. In addition to homemade gel mixtures, hydrogen peroxide-based hair bleaching creams available at beauty supply stores can also be used as a ready-made mix. Certain beauty salon products that are primarily composed of hydrogen peroxide can also be used as an alternative to retr0bright, as it has been discovered to be almost identical in effect, and already "creamy" so that it can be applied less wastefully to yellowed plastics. While this eliminates the difficulty of having to put together a batch directly from the instructions, one must be careful to apply the cream and wrap consistently and evenly to avoid streaks in the final product. Sodium percarbonate may also be used by dissolving it in water and following the usual steps for hydrogen peroxide, as it is sodium carbonate and hydrogen peroxide in a crystalline form. Ozone gas can also be used for retr0brighting and is simple, as long as an ozone generator and a resealable plastic bag of sufficient size are available, but takes longer than with hydrogen peroxide and other methods. Heat may be used as a substitute for UV exposure, submerging ABS plastic in 40 unit hydrogen peroxide solution at 71°C has been shown to be effective.
