Within the retro computing community there exists a lot of controversy about so-called ‘retrobrighting’, which involves methods that seeks to reverse the yellowing that many plastics suffer over time. While some are all in on this practice that restores yellow plastics to their previous white luster, others actively warn against it after bad experiences, such as [Tech Tangents] in a recent video.
After a decade of trying out various retrobrighting methods, he found for example that a Sega Dreamcast shell which he treated with hydrogen peroxide ten years ago actually yellowed faster than the untreated plastic right beside it. Similarly, the use of ozone as another way to achieve the oxidation of the brominated flame retardants that are said to underlie the yellowing was also attempted, with highly dubious results.
While streaking after retrobrighting with hydrogen peroxide can be attributed to an uneven application of the compound, there are many reports of the treatment damaging the plastics and making it brittle. Considering the uneven yellowing of e.g. Super Nintendo consoles, the cause of the yellowing is also not just photo-oxidation caused by UV exposure, but seems to be related to heat exposure and the exact amount of flame retardants mixed in with the plastic, as well as potentially general degradation of the plastic’s polymers.
Pending more research on the topic, the use of retrobrighting should perhaps not be banished completely. But considering the damage that we may be doing to potentially historical artifacts, it would behoove us to at least take a step or two back and consider the urgency of retrobrighting today instead of in the future with a better understanding of the implications.
At the heart of the issue lies the misconception that all plastics are alike, and what damages one damages all. This is not so: there are plastics that go brittle on their on, while others don’t; there are plastics that are negatively affected by retr0bright while others ain’t. Treating the problem as if the plastics of a Dreamcast behave in the same way as the plastics on a SNES is not the way to look at these problems.
There are not much polymers that can resist a very strong oxidant like H2O2 or O3 anyway…
retrobright creates retrodust
I would consider a multi part treatment. Strong oxidants can remove discoloration but they probably create many acidic sites which can later easily yellow. So you probably need to esterify them or something similar. Perhaps cost them in an antioxidant after. Not sure but in most cases oxidants are used to age materials not the opposite!