Editing Super Famicom Maintenance Guide (section)

== Yellowed plastic ==

The Super Famicom's upper shell is the machine's most recognisable ageing problem. The grey ABS discolours unevenly, commonly with the top shell affected far more than the base and often in patches rather than uniformly.

Treatment is possible; see [[Retrobrite]] for the chemistry, the procedure and its risks. Two things worth knowing before you start:

* The discolouration is in the body of the plastic, not on the surface, so cleaning will not touch it.
* Over-treated ABS becomes brittle and the finish goes chalky. Watch the temperature and the exposure time, and stop early rather than late.

The coloured buttons, the cartridge slot dust flap and the base are usually less affected than the top shell, so treating the whole case uniformly can leave you with a mismatch you did not have before.