Mirror cleaning for a Newtonian

A friend of mine has a Newtonian reflector. He says it's got some fairly
heavy spotting on it, probably due to condensation and evaporation. It's
been years and years and years, probably three decades or more, since I last
cleaned a first-surface mirror. What's the latest and greatest on how to do
it? I haven't examined the mirror yet, but we'll be getting together the
first weekend of October to clean the mirror and recollimate the scope.

"Bob Bethune" wrote in message
...
A friend of mine has a Newtonian reflector. He says it's got some fairly
heavy spotting on it, probably due to condensation and evaporation. It's
been years and years and years, probably three decades or more, since I
last
cleaned a first-surface mirror. What's the latest and greatest on how to
do
it?

It depends.

If I am cleaning a small mirror, I fill a clean plastic dishpan with hot
soapy (Ivory or Dawn or somesuch dishwashing liquid) water.
Soak the mirror for 20 minutes or so. Agitate the water, rock the mirror
back and forth, without actually touching the surface.
Rinse it off with a steady stream of cold water. Blot the droplets with a
paper towel edge.

I have never tried putting the mirror in an automatic dishwasher. I really
want to try it. Especially with those much-touted anti-spotting detergents.

If the mirror presents favorably after this treatment, I put it back to
work. If not, I use new cotton swabs dipped in a 50/50 mixture of denatured
alcohol and water. Brush lightly across the face with this mixture,
exerting no pressure. Use horizontal or vertical strokes, not circular
strokes. Change cotton swabs (cotton balls) frequently, to avoid having
material lossened from the swabbing dragged across the mirror and possibly
damage it. Rinse with alcohol, then distilled water. Blot with a paper
towel as before.

If the mirror presents favorably after this treatment, I put it back to
work. If not, I go outside and get five gallons of acetone, 20 gallons of
distilled water, and notify the fire department.

If the acetone doesn't work, there's always USP Ether. Trouble is, after 10
minutes of washing with ether, you can't find your mirror, or the ether, and
you can't tell if the mirror is dirty or not. But it doesn't matter because
it wasn't that important anyway, and you're feeling pretty good and it's
time to listen to some jazz.

Regards,
Etok



__________________________________________________ ____________________
Posted Via Uncensored-News.Com - FAST UNLIMITED DOWNLOAD - http://www.uncensored-news.com
The Worlds Uncensored News Source

"Bob Bethune" wrote in message
...
A friend of mine has a Newtonian reflector. He says it's got some fairly
heavy spotting on it, probably due to condensation and evaporation. It's
been years and years and years, probably three decades or more, since I
last
cleaned a first-surface mirror. What's the latest and greatest on how to
do
it? I haven't examined the mirror yet, but we'll be getting together the
first weekend of October to clean the mirror and recollimate the scope.






General guidelines for cleaning optics and mirrors.



http://home.earthlink.net/~astralnomicon/cleanins.htm

etok wrote:

If the acetone doesn't work, there's always USP Ether. Trouble is, after 10
minutes of washing with ether, you can't find your mirror, or the ether, and
you can't tell if the mirror is dirty or not. But it doesn't matter because
it wasn't that important anyway, and you're feeling pretty good and it's
time to listen to some jazz.


But for God's sake don't light up and have a smoke.

"etok" wrote in message ...
"Bob Bethune" wrote in message
...
A friend of mine has a Newtonian reflector. He says it's got some fairly
heavy spotting on it, probably due to condensation and evaporation. It's
been years and years and years, probably three decades or more, since I
last
cleaned a first-surface mirror. What's the latest and greatest on how to
do
it?

It depends.

If I am cleaning a small mirror, I fill a clean plastic dishpan with hot
soapy (Ivory or Dawn or somesuch dishwashing liquid) water.
Soak the mirror for 20 minutes or so. Agitate the water, rock the mirror
back and forth, without actually touching the surface.
Rinse it off with a steady stream of cold water. Blot the droplets with a
paper towel edge.

I have never tried putting the mirror in an automatic dishwasher. I really
want to try it. Especially with those much-touted anti-spotting detergents.

If the mirror presents favorably after this treatment, I put it back to
work. If not, I use new cotton swabs dipped in a 50/50 mixture of denatured
alcohol and water. Brush lightly across the face with this mixture,
exerting no pressure. Use horizontal or vertical strokes, not circular
strokes. Change cotton swabs (cotton balls) frequently, to avoid having
material lossened from the swabbing dragged across the mirror and possibly
damage it. Rinse with alcohol, then distilled water. Blot with a paper
towel as before.


Here are the two most important rules:

1) DO NOT USE ALCOHOL WITH AN ALUMINIZED MIRROR!
2) DO NOT LISTEN TO ETOK.

Contact the manufacturer for their recommendations.

Hi Bob,
Those spot may be permanent by now.

The best cleaning, I have found, involves blowing off the dust and
then soaking in lukewarm water with Dawn dish soap. I gently drag a
paper towel over it and then rinse thoroughly with lukewarm water.
Keep the mirror wet and do not let any water dry as it will leave some
residue behind. I then use compressed, dry nitrogen(50 lbs air gun). I
blow off the water very quickly. After a few hundred cleanings, I have
found this to be the finest means of mirror cleaning.

The problem is finding the compressed nitrogen tank with pressure
regulator and air gun.

Al M



"Bob Bethune" wrote in message ...
A friend of mine has a Newtonian reflector. He says it's got some fairly
heavy spotting on it, probably due to condensation and evaporation. It's
been years and years and years, probably three decades or more, since I last
cleaned a first-surface mirror. What's the latest and greatest on how to do
it? I haven't examined the mirror yet, but we'll be getting together the
first weekend of October to clean the mirror and recollimate the scope.

1) DO NOT USE ALCOHOL WITH AN ALUMINIZED MIRROR!


EXPLAIN!


john

I've used isopropol alcohol for over 40 years....but I
don't use it straight....for your 2nd step, you mix up
a solution of 2/3 distilled water, 1/3 alcohol, and
1 or 2 drops of dishwater soap, and apply to mirror in straight
strokes with surgical cotton. Then rinse, first tap
or spring water, then rinse distilled water.
(The little alcohol in there helps with oils, cigarette smoke,
etc)...but this is only once or twice a year process).
FWIW,
Tom W.




Jskies187 wrote:

1) DO NOT USE ALCOHOL WITH AN ALUMINIZED MIRROR!


EXPLAIN!


john

"etok" wrote in message ...
"Coppy Littlehouse" wrote in message
m...


Here are the two most important rules:

1) DO NOT USE ALCOHOL WITH AN ALUMINIZED MIRROR!
2) DO NOT LISTEN TO ETOK.

With all due respect, Coppy, you should wear safety glasses when grinding an
axe.
The following sources recommend using alcohol with aluminized mirrors:
The Gemini 8m telescope:

[snip of everyone recommending alcohol]

The CTIO .9M telescope staff have this info on alcohol cleaning their
mirror:
"We used isopropyl alcohol at the end of the rinsing but this did leave a
few ugly whitish marks that we could not recover with another soap wash.
Rancourt explains (Optical Thin Films, User's handbook, McGraw Hill 1987)
that the 'evaporation of the solvent on the surface beeing cleaned will
reduce the temperature locally and may cause the moisture in the air to
condense in the vicinity of the droplet, leaving a mark when water dries'
(p175). This might be what happened. Since then, we do not use alcohol
anymore in our washings... "


So... you're saying that I'm right. Is that it?

On 16 Sep 2003 06:24:25 -0700, (Al M) wrote:


The problem is finding the compressed nitrogen tank with pressure
regulator and air gun.

Al,

I use O2 from my cutting torch nozzle to "air knife" the water off
mirrors prior to aluminizing or after cleaning an already aluminized
surface. Works good, cheap, and another good excuse for wanting to
own a "hot wrench"


Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction, Testing, and Coating site)