🔗 Retrobright
Retrobright refers to H2O2 (hydrogen peroxide) based processes used to remove yellowing from ABS plastics. The usage has also expanded to other retro restoration applications, such as classic and collectible sneaker restoration, where it is referred to by collectors as "sole sauce".
Yellowing in ABS plastic occurs when it is exposed to UV light or excessive heat, which causes photo-oxidation of polymers that breaks polymer chains and causes the plastic to yellow and become brittle.
One method of reversing the yellowed discoloration coined the term (stylized as retr0bright or Retrobrite) 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.
The long-term effectiveness of these techniques is questioned. Some have discovered the yellowing reappears, and there are concerns that the process weakens and only bleaches the already damaged plastic.