Sky & Telescope - March 2019 - 38

Telescope Care

t FIRST BATH Top: Flooding the mirror
with warm tap water will remove a lot of
the dirt. Middle: Gently swipe a soapy
wet cotton ball across the mirror. Use a
fresh cotton ball for each pass to avoid
scraping grit particles across the mirror
again and again. Bottom: Use your soapy,
softened fingertips to feel for any remaining grit particles.

I've never had quite the courage
to do that, but I believe he's right.
I have cleaned mirrors with Glass
Plus and Kleenex without harming them. But there's a tried-andtrue method that's safer, and it's
easy enough that it should be your
standard method, too.
First, remove the mirror from
its cell if possible. If you can't, then
you'll have to clean it in the cell, as
I've done in the illustrations here.
Next, blow off any dust that you
can. Don't use a high-pressure air
jet; just puff away whatever is loose.
Get a couple dozen cotton balls
ready. You'll want to be able to
pick them up one at a time with
wet hands.
Have some distilled or deionized
water ready, too.
Take off your rings.
Trim your ﬁngernails. Seriously.
Prepare a bowl of warm, soapy
water. Add just a couple drops of
Dawn, Ivory, or some other gentle
dish soap. Unscented is best (fewer
additives), but that's not critical.
Wash your hands ﬁrst to get most
of the oils off, then soak the ﬁngertips of your dominant hand for a
few minutes in the mirror-washing
water. This will soften up your skin
and get it squeaky clean.
Next, rinse the mirror under
warm running water. From this
point on, don't let any water dry
on the mirror. Tap water leaves
mineral deposits when it dries, and

Mirror

COATING
SERVICES
Here's a list of companies that currently
provide aluminization
services for amateurs
in North America.

those are hard to get off.
Rinse off all the dirt you can.
Use your sink sprayer if it has one.
You might even soak the mirror for
a while if you have stubborn spots.
Once you've gotten off everything you can with running water,
start in with the cotton balls. Take
a single cotton ball, dip it in the
soapy water, and, starting at the top
of the mirror, wipe it gently across
the mirror in one steady, light swipe
from one edge to the other. Now
throw that cotton ball away. If the
cotton picked up any grit, you don't
want to be scraping it across the
surface on your next pass.
Work your way down with overlapping horizontal motions, using
one cotton ball per swipe. (Yes, if
you're careful you can rotate the
cotton ball and get a second clean
swipe out of it.)
When you've done the entire
mirror, rotate it 90° and do it again.
Now take a deep breath and
touch the mirror with your ﬁngertips. (This is why you trimmed
your ﬁngernails - you just want
the ﬂeshy parts of your ﬁngers to

Aluminum Coating
807 Rutherdale Ave.,
San Carlos, CA 94070
650-868-5035
alcoat.net

Evaporated Metal Films
239 Cherry St.,
Ithaca, NY 14850
800-456-7070
dynasil.com

H. L. Clausing, Inc.
8038 N. Monticello Ave.,
Skokie, IL 60076
847-676-0330
clausing.com

Evaporated Coatings Inc.
2365 Maryland Rd.,
Willow Grove, PA 19090
215-659-3080
evaporatedcoatings.com

Galaxy Optics
P.O. Box 2045,
Buena Vista, CO 81211
719-395-8242
galaxyoptics.com

North American
Coating Laboratories
9450 Pineneedle Dr.,
Mentor, OH 44060
866-216-6225; nacl.com

M A RCH 2 019 * SK Y & TELESCOPE

http://www.alcoat.net http://www.clausing.com http://www.dynasil.com http://www.evaporatedcoatings.com http://www.nacl.com http://www.galaxyoptics.com

Sky & Telescope - March 2019

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