How to de-yellow old plastic casings
(The Retrobright Method)

During the winter of 2009, I tried out the Retrobright method to de-yellow a very yellowed Nintendo Super Famicom console I imported from Japan.

These were the tools and ingredients I used:

1. Six 32oz bottles of 3% Hydrogen Peroxide (only 97 cents per bottle at Wal-Mart, and works just as well as the 30-40% H2O2 everyone recommends - 40% H2O2 is VERY dangerous if you don't know how to handle it. A 3% H2O2 solution is JUST FINE, and using a concentration higher than 10% is stupid, idiotic, and an unnecessary risk of your life and any others within a 10-foot radius of you... at least IMO)

2. 1/4 teaspoon of Oxi Clean

3. A relatively small plastic tub (with at least 10" x 10" area)

4. Nice, cold-ish weather to avoid plastic warping (approximately 40-50 degrees F)

5. SUNLIGHT!! Lots and lots of it! (Best during the wintertime, when all the leaves are gone and skies are cloudless)

Basically, I mixed a solution of hydrogen peroxide and Oxi Clean, dismantled the Super Famicom, soaked the plastic case in the solution, left it out in the sun for approximately 10-12 hours, then wiped the case dry and put the console back together.

There's some interesting chemistry involved with the changing color of old plastic. Computers and video game consoles back in the 80s and early 90s had casings made of ABS plastic (Acrylonitrile butadiene styrene). ABS plastic contains trace amounts of bromine as a flame retardant, which reacts with the plastic components and turns them yellow through oxidation, using UV light from direct sunlight as a catalyst. The hydrogen peroxide + Oxi Clean solution with UV light reverses this reaction and reverts the plastic to its original color.

This was the first time I had ever taken a video game console apart (or really, any electronic apparatus of any kind) and it was a challenge keeping track of all the different screws and small plastic pieces. It took a lot of patience and attention to detail, and the experience of taking the console apart and putting it back together again pretty much gave me the courage to try other similar things, like modding Game Boys and upgrading computer components!

As for the Super Famicom console, the procedure did make the color revert to a nice shade of gray. The one thing I didn't do (which, in hindsight, is probably the most important thing I should have done) was coat the plastic with a UV-resistant primer or sealant, so the plastic won't turn yellow again. Since I didn't do this, the console eventually ended up turning yellow again. The plastic also became very brittle over time, though I'm not sure if the Retrobright procedure contributed to the brittleness or not. The plastic casing eventually cracked in several places, and a couple of years ago I ended up replacing it with a new aftermarket shell (a story for another time!)