Re: [ATM] Moisture resistant baffles

["Don Clement" <clement.focuser@verizon.net>]

I use Krylon 1602 Ultra Flat Black paint  (available from Wal-Mart) on the
inside surface of the Hypalon rubber bellows of my focuser.  The rubber
bellows are turned inside-out and run through an automatic dish washer to
remove the corn starch used as the mold release. The inside surface is then
cleaned with alcohol. Rubber gloves are used when handling the bellows to
avoid finger oil contamination. (Warrick Brown recommended).  The bellows
are mounted inside out on a mandrel and sprayed with Krylon 1602. Krylon
adheres best when the temperature of the paint can and Hypalon rubber is
>85* F. It is important to only spray a very, very thin layer or the paint
will not adhere well to Hypalon rubber. Also important is to vigorously
shake the can for at least two minutes just prior to spray painting.



 The pleated internal surface is just as important to trapping reflected
light as the flat black coating. The combination of 3/8" thick pleats of the
circular rubber bellows and thin coating of Krylon ultra flat black make for
a far superior internal baffle (especially at the longer wavelengths where
CCDs are most sensitive) than black anodized solid tubes found in other
focusers. The circular rubber baffles are not only moisture resistant, but
also dust proof, light tight, and air tight.



Don Clement

Running Springs, California

http://www.ClementFocuser.com

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