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A TRS-80 Color Computer 2 case showing significant yellowing
A TRS-80 after treatment, showing the yellowing largely reversed

Retrobright (Stylized as Retr0bright) is a chemical mixture used to remove yellowing from ABS 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.

Yellowing is caused by both bromine and exposure to ultraviolet (UV) 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.[1]

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.[2][3]


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:

  • Hydrogen peroxide solution. 12% or 6% work the same.
  • Approximately 1/4 teaspoonful (4.9 ml) per gallon (3.8 l) (1/3072) of Tetraacetylethylenediamine (TAED)-based laundry booster (concentrations of TAED vary).
  • UV light, either from sunlight or a UV lamp.

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.

It has been realized by some that certain beauty salon products that are primarily composed of hydrogen peroxide can be used as a ready-made alternative to Retr0bright, almost identical in effect, already "creamy" so that it can be applied less wastefully to yellowed plastics (especially large devices such as computer panels or monitors) without any of the hassle of having to put together one's own batch using the Retr0bright instructions.[4]


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