Canned Air

(Wfoley2) wrote in message ...
Canned air might be OK for cleaning crap out of a keyboard or smoke alarm. It
is NOT a good idea for optics. There are lens brushes for this purpose. If
canned air will blow it off, then a brush will brush it off. Be sure the brush
is clean and without oils on it.
Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

I often use canned air to clean optics. The cautions about using it
slowly and only when the can is warm are true as otherwise it will
leave residue. Generally, if used at very slow rate, the impact
velocity of most dust should not be a problem.
I hand polish metal x-ray optics and use it to remove distilled water
from the mirror surfaces because no matter how pure the water, it
always leaves residue if allowed to form spots. Often, we use pure
gold surfaces and the gold is so soft that any brush will scratch it
so that is why we use the canned air.
Glass surfaces and the layer of Aluminum oxide on a telescope mirror
is probably harder than most of my optics so I do not expect canned
air to cause any pits or scratches.

On 01 Mar 2004 14:32:52 GMT, (Wfoley2) wrote:

Canned air might be OK for cleaning crap out of a keyboard or smoke alarm. It
is NOT a good idea for optics. There are lens brushes for this purpose. If
canned air will blow it off, then a brush will brush it off. Be sure the brush
is clean and without oils on it.

I couldn't disagree more. I've used it for years for cleaning all sorts of
optics in the lab. It isn't difficult to use it in a way that prevents liquid
propellants from getting on the optics. You just need to start the air flowing
while it is pointing away from things. It does a much better job of cleaning
than a brush in many cases. I wouldn't use it on a front surface mirror, but on
just about anything else, no problem. Worst case, the propellant isn't going to
hurt glass or coated optics, even if you screw up.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

There are lens brushes for this purpose. If
canned air will blow it off, then a brush will brush it off.

Hi Bill:

Certainly there are differences of opinion, but, in general in my _opinion_,
canned air is more than safe enough for optics (other than mirrors) and is less
apt to cause damage than a brush.

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

Chris L Peterson wrote in message . ..
On 01 Mar 2004 14:32:52 GMT, (Wfoley2) wrote:

Canned air might be OK for cleaning crap out of a keyboard or smoke alarm. It
is NOT a good idea for optics. There are lens brushes for this purpose. If
canned air will blow it off, then a brush will brush it off. Be sure the brush
is clean and without oils on it.

I couldn't disagree more. I've used it for years for cleaning all sorts of
optics in the lab. It isn't difficult to use it in a way that prevents liquid
propellants from getting on the optics. You just need to start the air flowing
while it is pointing away from things. It does a much better job of cleaning
than a brush in many cases. I wouldn't use it on a front surface mirror, but on
just about anything else, no problem. Worst case, the propellant isn't going to
hurt glass or coated optics, even if you screw up.


Why even worry? I use a hand-squeezed air bulb to blow off the last droplets
of distilled water after cleaning a front surface mirror. Been doing it for
decades with NO problems whatsoever, and the bulb is extremely inexpensive. I
bought mine at a photo shop so these should be readily available.

My telescope is new so I haven't found the need to clean the corrector
yet, but when I do, I decided to use what is called a "hurricane
blower" for camera lenses. This is basically a largish squeeze bulb
with a nozzle.

It works very well for even large camera lenses. Now my Telescope is
MUCH bigger, but I expect that it will work just as well. Any good
camera store should have one. The cost is about $5 (US).

On 1 Mar 2004 12:26:29 -0800, (Parallax) wrote:

(Wfoley2) wrote in message ...
Canned air might be OK for cleaning crap out of a keyboard or smoke alarm. It
is NOT a good idea for optics. There are lens brushes for this purpose. If
canned air will blow it off, then a brush will brush it off. Be sure the brush
is clean and without oils on it.
Clear, Dark, Steady Skies!
(And considerate neighbors!!!)

I often use canned air to clean optics. The cautions about using it
slowly and only when the can is warm are true as otherwise it will
leave residue. Generally, if used at very slow rate, the impact
velocity of most dust should not be a problem.
I hand polish metal x-ray optics and use it to remove distilled water
from the mirror surfaces because no matter how pure the water, it
always leaves residue if allowed to form spots. Often, we use pure
gold surfaces and the gold is so soft that any brush will scratch it
so that is why we use the canned air.
Glass surfaces and the layer of Aluminum oxide on a telescope mirror
is probably harder than most of my optics so I do not expect canned
air to cause any pits or scratches.

I've never seen "canned air" used in an optics lab and can't imagine
why you aren't using dry nitrogen.

Regards,
Bill Dean

Chris L Peterson wrote:

On 01 Mar 2004 14:32:52 GMT, (Wfoley2) wrote:
I couldn't disagree more. I've used it for years for cleaning all sorts of
optics in the lab. It isn't difficult to use it in a way that prevents liquid
propellants from getting on the optics. You just need to start the air flowing
while it is pointing away from things. It does a much better job of cleaning
than a brush in many cases. I wouldn't use it on a front surface mirror, but on
just about anything else, no problem. Worst case, the propellant isn't going to
hurt glass or coated optics, even if you screw up.

I guess a lot of us are just incompetent. Im sorry we are screwing up the world
so badly!
Jerry





_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

On Tue, 02 Mar 2004 06:02:58 GMT, Edward Smith wrote:

My telescope is new so I haven't found the need to clean the corrector
yet, but when I do, I decided to use what is called a "hurricane
blower" for camera lenses. This is basically a largish squeeze bulb
with a nozzle.

It works very well for even large camera lenses. Now my Telescope is
MUCH bigger, but I expect that it will work just as well. Any good
camera store should have one. The cost is about $5 (US).

Usually, correctors get contaminated by a mixture of atmospheric deposits
dissolved in dew. I've never found any kind of blower, including the high
pressure of canned air, sufficient for cleaning. Normally, you need some kind of
solvent. I use Windex, others use various homemade formulas consisting of water,
alcohol, or detergents.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Chris,

You have it dead on with below statement.

At the various thin film companies I worked for we found that contamination
of substrates was occurring within the first few seconds when using even
so-called dry nitrogen. We created the 10 second rule (blasting the nozzle
away from the substrate before aiming at the substrate). And the same is
true for canned air.

Dan McShane

Chris L Peterson wrote in message
...

You just need to start the air flowing while it is pointing away from
things.

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

If it comes in a Can, it must be Spam! The 10-second WWII rule.
Jerry

Dan McShane wrote:

Chris,

You have it dead on with below statement.

At the various thin film companies I worked for we found that contamination
of substrates was occurring within the first few seconds when using even
so-called dry nitrogen. We created the 10 second rule (blasting the nozzle
away from the substrate before aiming at the substrate). And the same is
true for canned air.

Dan McShane

Chris L Peterson wrote in message
...

You just need to start the air flowing while it is pointing away from
things.

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com