At 8:07 PM +0000 11/16/02, olympus-digest wrote:
>Date: Sat, 16 Nov 2002 08:58:49 +1300
>From: "Brian Swale" <bj@xxxxxxxxxxxxxxx>
>Subject: Re: [OM] ( OM ) why keep a filter in front of your lens
>
>Hi John & everybody
> > >>>
> >> It was soon obvious that there was a thick layer of accumulated grease of
> >> years on that glass.
> >
> > Do you think that, maybe, the grease was actually Vaseline, deliberately
> > applied to the filter to give a soft-focus effect?
> >
> > Just a thought.
> >
> > JohnOR
>
>The nature of the layer was very much tougher and with more resistance to
>moving. Almost more like baked-on cooking oil, but not so extreme.
I couldn't tell if you were able to get the hardened oil completely off. If
not, what *will* work is any methylene-chloride based paint stripper. (I use
"5f5".) Why? Because oil paint is precisely an oil that has cured by the
absorption of oxygen from the air. Actually, oil varnish is the pure oil,
while paint is the oil with mineral pigments mixed in. The original oil used
was linseed oil, but many other unsaturated oils will cure in the air. Some
such oils are also edible oils, like peanut oil, though peanut oil makes a
better food than paint/varnish base, ending up as an insoluable sticky mess.
Lay the filter bad-side-up on top of a piece of aluminium foil spread out on a
level surface. (The foil prevents the paint stripper from damaging the level
surface.) With a Q-tip, carefully coat the glass surface with paint stripper.
Wait a few minutes, then remove stripper and now-softened film with more
Q-tips. Clean up with acetone.
Paint stripper also works on mechanical components that have become gummed up
when the lubricating oil turned to varnish after long service.
What may also work is washing with *very* hot water, at least 60 degrees
centigrade (140 F), and hotter is better. If you can do this by hand without
using thick rubber gloves, the water is far too cool to do the job. One can
also just put the greasy filter in the dishwasher, set upright in the silver
tray, although this may take the lettering off.
Joe Gwinn
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