Bug Spray Vs. Optics - dissolves coatings

What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

Thanks,
Jerry

On Mar 31, 8:16*pm, jerry warner wrote:
What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

toluene?

Cheers

In message , jerry warner
writes
What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

The active ingredient of the DEET based formulations is a pretty good
and aggressive solvent for a lot of paints and plastics. It is usually
formulated in an ethanol water mixture. MSDS for repel is at:

http://www.repel.com/ProductCategori...rtsmenFormula/
MSDS/WipesMSDS.htm

I'd be surprised if it dissolved inorganic coatings on optics (but it
might create a thin oily surface patch that altered its optical
properties).

Pure ethanol will probably clean it off.

Regards,
--
Martin Brown

--
Posted via a free Usenet account from http://www.teranews.com

On Mon, 31 Mar 2008 01:16:28 -0600, jerry warner
wrote:

What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

DEET (N,N-diethyl-meta-toluamide)

--
Tom Hise - NCØO
N42° 07' - W91° 53'

On Mon, 31 Mar 2008 01:16:28 -0600, jerry warner
wrote:

What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

If you mean insecticide, I don't think there's anything universal. That
is, some insecticides (or their carriers) may be damaging, others not.

If you mean insect repellents, the most common (and only effective)
contain DEET. I've heard the story of it damaging optical coatings, and
tried to make it do so, without success. But it's definitely a solvent
for many plastics, and will damage coated plastic optics (found on some
cheap glasses and binoculars, as well as many eyeglasses). It also
damages some polymers found in clothing.
_________________________________________________

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

Chris L Peterson wrote:
If you mean insect repellents, the most common (and only effective)
contain DEET. I've heard the story of it damaging optical coatings, and
tried to make it do so, without success. But it's definitely a solvent
for many plastics, and will damage coated plastic optics (found on some
cheap glasses and binoculars, as well as many eyeglasses). It also
damages some polymers found in clothing.

Also, though it may not damage coatings on glass, if applied in spray
form it could contaminate nearby optics with traces of aerosol mist
which could leave a film on the surface..

-dave w

On Mon, 31 Mar 2008 07:57:20 -0700, David Weinshenker
wrote:

Also, though it may not damage coatings on glass, if applied in spray
form it could contaminate nearby optics with traces of aerosol mist
which could leave a film on the surface..

Yeah, it's something to keep away from optics. And the film itself is
oily, which could cause long term erosion of coatings (the problem is
that when you're someplace where you need to use DEET, you may not have
a very good way to clean oily films from optics). Also, the DEET could
cause damage to plastic around the optics that would then migrate out
onto the glass.
_________________________________________________

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

Thanks Martin
Jerry


Martin Brown wrote:

In message , jerry warner
writes
What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

The active ingredient of the DEET based formulations is a pretty good
and aggressive solvent for a lot of paints and plastics. It is usually
formulated in an ethanol water mixture. MSDS for repel is at:

http://www.repel.com/ProductCategori...rtsmenFormula/
MSDS/WipesMSDS.htm

I'd be surprised if it dissolved inorganic coatings on optics (but it
might create a thin oily surface patch that altered its optical
properties).

Pure ethanol will probably clean it off.

Regards,
--
Martin Brown

--
Posted via a free Usenet account from http://www.teranews.com

Chris L Peterson wrote:

On Mon, 31 Mar 2008 01:16:28 -0600, jerry warner
wrote:

What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

If you mean insecticide, I don't think there's anything universal. That
is, some insecticides (or their carriers) may be damaging, others not.

If you mean insect repellents, the most common (and only effective)
contain DEET. I've heard the story of it damaging optical coatings, and
tried to make it do so, without success.

I also have tried several times, without success.
Jerry

But it's definitely a solvent
for many plastics, and will damage coated plastic optics (found on some
cheap glasses and binoculars, as well as many eyeglasses). It also
damages some polymers found in clothing.
_________________________________________________

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

On Mar 31, 2:16*am, jerry warner wrote:
What is there in bug spray that dissolves coatings and some
paints on eyepieces? Does anyone know?

Thanks,
Jerry

There are many different kinds of coatings today, from simple
antireflection to simple aluminum reflectance coatings. The simplest
antireflection coatings consist of a micro-thin layer of magnesioum
fluoride. These can be quite soft or somewhat hard, depending on how
they were applied. If they were applied in a vacuum chamber where the
vacuum was not ideal, and if the substrate glass was not heated to a
high enough temperature, then the coating will be relatively fragile.
It can come off the glass easily and can be affected by strong
chemicals. Unfortunately, one cannot know how well the coatings were
applied by the coating lab, so it is best to treat them as gently as
possible and not let any contaminant touch the surface.

This is doubly true of aluminum mirror coatings. If they are not
applied properly and do not have a protective coating, they will be
easily degraded any number of ways, from judicial cleaning to simple
atmospheric dew settling on the surface.

Modern multi-coatings can be super rugged and hard. These are applied
in a more robust manner using ion beam acceleration, which imparts
enough energy to the particles to fuse them into the subsurface of the
glass. These type of coatings are tough enough to stand repeated
cleaning and will not allow water from dew drops to seep into the
structure (lesser coatings are porous which allows water and liquids
to penetrate and ultimately destroy the coating). Dew is especially
bad for any type of coating because it contains dissolved carbon
dioxide, and thus is a weak form of carbonic acid. These newest
coatings using ion assist implantation are pretty much impervious to
dew.

I have a large Mak-Cass permanently mounted in an observatory in a
climate that has heavy moisture content in the air, and had many
occasions of the internal optics drenched in dew, even though they are
in a closed tube. Even after 5 years of this, the coatings wipe
perfectly clean without any scratches or sleeks. Dew spots come off
clean without residue on all internal and external surfaces with
simple application of Balzer's #2 Substrate Cleaner. One of the guys
here who has a large Newtonian in his observatory can get scarcely 6
months out of his coating (simple aluminum coat from Clausing) before
it develops a serious case of measles. The only drawback to modern ion
implant coatings is the cost - approximately $800 per coating run. And
contrary to popular belief, these coatings do not change the figure of
the mirrors or lenses - my Mak-Cass tested the same before and after
coating, on the interferometer.

Rolando