Plastic knobs, fungus and cleanup

[Christian Fandt]

Here's a question I've been wondering about for quite awhile.

What exactly is the type of plastic many knobs are made of which, after a
period of time in a dark, moderately damp place, develop what looks like a
white fungus upon the surface??

I'm sure most of you have seen this. I'm suspecting the white stuff is a
fungus based upon its appearance and conditions it would develop. I suspect
that finger oils which collect on the knob surface over time feed the
fungus, perhaps the plastic itself (being an organic compound) feeds the
fungus. The type of plastic material is dependant upon whether this happens
or not it seems. That is to say, I don't see it on knobs which seem to be a
somewhat diff. material while under the same condx. The clear/translucent
knobs are the most likely to exhibit this it seems, but color doesn't
matter. The typical amber-yellow or clear screwdriver handles are
apparently of the same material and show this too.

As for cleanup and restoration, the once shiny surface of a knob (or
screwdriver handle) ends up dull and somewhat pitted -depending upon the
severity of the collection of fungus. Anybody devised a way to bring back
the original gloss? Seems a clear lacquer or enamel paint would help a bit,
especially to at least seal the surface.

Thanks for enlightening me!

Regards,  Chris
-- --
Christian Fandt,         Electronic/Electrical Historian
Jamestown, NY  USA      cfandt at netsync.net
Member of Antique Wireless Association
        URL: http://www.ggw.org/awa

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