Particularly light-colored plastic parts do not tolerate UV radiation well, as demonstrated by computer cases from the 1980s and 1990s, which many people remember as being yellowed. These were once light gray or white.
I have often read about methods for chemically reversing this yellowing. “retr0bright” is one such method.
I decided to try a slightly different approach:
The basic chemical used to remove the yellowing is hydrogen peroxide, a rather dangerous substance that is also subject to certain trade restrictions. The problem is not only obtaining this chemical, but also applying it evenly to the plastic part so that it bleaches evenly.
It turns out that there is a “ready-to-use” solution to both problems, available in stores that sell cosmetics and hairdressing supplies. Namely, “oxidation developer”!
Legal framework
The maximum concentration that such an oxidation developer is allowed to have in Germany or Europe is 12% hydrogen peroxide. That may not sound like much, but it is – it has a strong effect on the skin and must be used with extreme caution.
There are several ready-made containers available with this concentration level. I bought a very inexpensive version of “Comair*” in a 1-liter container.
Using it
It’s actually quite simple:
- Clean the plastic part thoroughly, preferably with isopropanol.
- Remove or cover anything that is sensitive (stickers).
- Apply the cream as evenly as possible to the plastic part with a brush.
- Wrap the coated object in cling film.
- Place in direct sunlight or use a UV light source.
…it works. With the sun as a UV source, it takes a few hours or, in some cases, several days for a few hours, but it works really well. It is advisable to check regularly how far the plastic has faded in order to catch the right moment to take it out of the sun.