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

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. Bromine is added to ABS plastic as a fire retardant.


Retr0bright consists of hydrogen peroxide, a small amount of an "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, the stronger the better. 12% works fine; 6% works also, just more slowly.
  • 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.

External links

  • Official website
  • Un-Yellow Old Plastics - Retr0brite! (Make blog)
  • Open source computer polish: Retr0Brite (Boing Boing)
  • - Retr0bright Support Thread