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Subject: RE: [MAPUG]: Re: LX200 damaged corrector plate?
From: Michael Hart
Reply To: mapug@shore.net
Date: Sat Sep 28 00:19:28 1996

David Williams said on 9/27/96:

>A few months ago I was cleaning my corrector plate with Dust-Off (canned
>air). I have always used this carefully because I know that if you shake the
>can, or move it too rapidly, it can eject a substance onto the surface that
>is being sprayed. I had the nozzle rather close to the plate--2 to 3 inches.
<snip>

Most of us know that the various "dust" removers out there are not really
"canned air" but diflluoroethane (Dust-Off), 1,1,1,2-tetrafluoroethane
(Office Duster & others) and other non-fluorocarbon based products.

This is one product that works well when used with caution in the gaseous
state. In the liquid state (easy to get with long presses or tipping can), these
dust removers become powerful solvents that can dissolve plastic and damage
first surface mirror coatings.

After accidentally damaging several items, I realized that in referring to that
dust removal spray as "canned air", I sometimes forgot and used the dust
removal spay interchangeably for filtered dry air, which it isn't, period.

Air from a standard compressor is usually poorly filtered, can contain small
amounts of oil and can be and is often near saturation. I prefer argon or nitrogen.

Michael Hart
mhart@netexpress.net