Last updated: 12 August 2012

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Cleaning Optics

From: (Kevin P. Kretsch)
Having seen a number of questions about cleaning the optics on the ETX, and being an optical physicist, I thought I'd give some advice.

The ETX optics will not need cleaning unless a great glob of something lands on the corrector. Do not try to blow dust of the corrector, you'll just cover the corrector with spit. (THEN it will need cleaning!)

Dust, or the occasional hair, will not affect the performance of the scope. A little dust will drop the light transmission, but the human eye will not see that small a change (unless it's REALLY covered!), It takes a lot of dust for diffraction limited performance to be affected.

If you do have to remove dust, use a can of clean compressed air, available from RS. If any dust stays on the corrector, or you dont have an air can, then use a soft camel-hair type brush, available in any good camera store, and gently with MINIMUM PRESSURE brush the dust towards the edge of the corrector. If you ever NEED to clean inside the ETX, ONLY use the air can. NEVER UNDER ANY CIRCUMSTANCES make contact with ANY mirrored surface inside the ETX. You really risk damage if you do, damage that you can't easily fix.

Really nasty finger marks on the corrector can be removed with an appropriate solution. "Neat" iso-propanol, used as described below would be my first choice, but I have NOT tried it, as I don't know how it will affect the coatings. I'm in NO hurry to find out! The 90-EC manual suggests 3:1 distilled water/propanol solution. (Make sure it is distilled, not just deionised.)

With whatever solution you choose, use lens cleaning tissue, folded to a 1/2" pad, and add a few drops of solution, just enough to lightly wet the pad. Avoid touching the part of the pad to be in contact with the optics. The use a SINGLE stroke across the mark, toward the outside of the corrector. Then throw the pad away and use another. It's an idea to cut the pads in half first, with a sharp scissors, so you don't go through too many packs for one mark! But, if you do, take care to fold so that the cut edge of the tissue is INSIDE the pad. Draw the pad very slowly across the area to be cleaned. IF you go too fast, you'll just leave solution on the optics and might leave a mark when it dries. Use medium-light pressure at first, and as the mark starts to clear, use less and less pressure until you literally barely drag the pad across the surface.

Hope this is useful, and if I wasn't clear before, DON'T WORRY TOO MUCH ABOUT DUST. It's not a big problem.

Clear skies,


Kevin P. Kretsch B.A.(Mod.)Phys e-mail:
Photonic Materials Group, Tel: +353 1 608 1324
Department of Physics, Fax: +353 1 671 1759
Trinity College, Dublin 2, IRELAND.

Subject: LensPen
Sent: Sunday, April 4, 1999 16:33:33
From: (Joe Hartley)
I had been vexed by some crud on 2 of my lenses, both Meade Series 4000 Plossls - the 9.7mm and the 26mm. I know some people can be fanatical about not cleaning lenses for fear of scratching or marring the lens or its coating, but these particles on my lenses were so distracting I felt I needed to clean them somehow.

Trying a tissue moistened with distilled water hadn't done much, nor did canned air or a "blower" bulb. I had yet to try isopropyl alcohol as I didn't have any to hand that was pure (I only had 70% rubbing alcohol in the house, which has other chemicals in it which might leave a residue).

Based on some comments in the USENET group sci.astro.amateur, I went out and picked up a gizmo called a LensPen MiniPro at the local Ritz camera for $7.99.

The LensPen has a retractable soft brush on one end, and a unique flexible cleaning tip on the other end. This cleaning tip, which is 7mm in diameter on the MiniPro and 15mm on the regular LensPen, uses a carbon-based cleaning compound to help get rid of smudges like fingerprints.

I'm very happy to say that the LensPen did a wonderful job on the lenses! The brush took off most of the particles, and almost all of rest easily came off with the cleaner tip. There was one relatively big particle that seemed particularly stubborn. I used my fingernail (gasp!) to dislodge it, then swept it off with the brush. Of course, I'd left a fingerprint on the lens. This came off in seconds with the cleaning tip, leaving me with a very clean eyepiece. No discernable flaws, marks or scratches were visible in the lens coating, and some terrestrial test views shows the lenses to be nice and clean. No residue from the cleaning tip was visible after use.

Eyepiece lenses seem to pick up a lot of dirt from sitting outside on the scope while it sits unused (soot? comet dust? Who knows?). This is not as bug a problem with the main corrector lens on the ETX, likely thanks to my dew cap, so I haven't needed to do anything to that surface except brush a little dust off it.

I'm really happy with this little unit. It seems a lot safer and easier than using lens tissues or cloths on the eyepieces, and is very inexpensive. There is a website for the LensPen at but is not sold through that website. It seems widely distributed through photo stores.

Joe Hartley - - brainiac services, inc
12 Emma G Lane, Narragansett, RI : 02827 - vox 401.782.9042: fax 401.782.8782
Without deviation from the norm, "progress" is not possible. - FZappa

Sent: Wednesday, March 22, 2000 13:22:47
From: (Glenn Dunlap/CAM/Lotus)
I thought I would share a tip on cleaning lenses with your readers.

The lens on my ETX-125 was starting to sport a fairly good number of spots on it from where droplets of condensation had dried. It had also collected a bit of dust. Although the image quality was still excellent I'm the kind of guy who just can't leave well enough alone and so I decided to clean the lens. Even though the method that I employed worked very well and did not harm the lens at all I would still suggest that people not clean their lens unless it's gotten pretty grotty. It really does take quite a bit of junk on the lens for image quality to be noticeably impaired.

OK, so here's what I did.

1) buy a gallon of distilled water, a bottle of isopropyl alcohol, and a bottle of biodegradable dishwashing liquid and a small can of compressed air (available at camera stores). Mix up 1 pint of cleaning solution consisting of 3 parts distilled water, 1 part isopropyl alcohol, and 1 drop of dishwashing liquid. Fill a *clean* spray bottle with this solution. This is a solution which is Meade-sanctioned.

2) fill another *clean* spray bottle with just distilled water.

3) remove the lens cover, give the lens a good blow job with the compressed air, align the scope's tube so that it is parallel with the fork arms, and then suspend the ETX upside down over a sink, bathtub, etc. so that the lens is facing straight down. Allow for a 2 or 3 foot gap between the lens and the sink. It's up to the reader to figure out exactly how to suspend the scope ... just make damn sure you suspend it securely and that you don't drop it in the process (ouch!).

4) trim your fingernails short and wash your hands carefully.

5) spray a liberal amount of the cleaning solution on the lens. any excess will drip into the sink.

6) use the tip of a finger to *gently* rub the entire surface of the lens.

7) liberally spray the lens with distilled water until you're satisfied that the cleaning solution has been removed.

8) tilt the tube a little (loosen the dec knob a little if necessary) so that the tube is no longer pointed straight down. This will allow water droplets on the lens surface to run off to the edge of the lens.

9) soak-up the water that is at the edge of the lens by dipping the corner of a paper towel into the water being careful not to let the paper towel brush against the lens.

10) At this point you should have a nice clean lens with some water droplets scattered here and there across its surface. Now you can carefully unsuspend the ETX and place it upright on a table. Remove the majority of the remaining water droplets from the lens surface by employing the same technique of carefully dipping the corner of a paper towel (or maybe now you want to switch to lens tissue and use the corner of the lens tissue) into each remaining water droplet to soak it up. When you're finished there will be remarkably little evidence that the lens just took a good bath ... aside from being very clean. :-)

What I like about this procedure is that you don't ever rub the lens with anything other than the tip of your finger and the rubbing that you do do is minimal and is very light, lubricated rubbing. It also leaves the lens *sparkling* clean. I'm guessing that unless you use your scope *a lot* there is probably no need to do this procedure more than 1 or 2 times a year.

Thanks for taking the time and effort to maintain such a great site.


LensPens Mike here: I purchased the dual set of LensPen and LensPen MiniPro from Scopetronix ($17) to see if they really worked. They do. Both pens have a nice brush that retracts. At the other end is the lens cleaner; a rubber-like surface but is soft enough to not damage the lens or coating. The larger model surface is about 1/2" in diameter and is used for larger surfaces (35mm camera lens, binoculars, or telescope objectives). The smaller pen is about 1/4" in diameter and works well for eyepieces or other small lens. I had a rather stubborn bunch of small "dots" on one of my eyepieces; they defied removal by regular cleaning methods. The LensPen miniPro got them off without leaving any smears. I then tried out my ETX-90RA and eyepieces; no distortions or blurriness was evident and the views were clean. These are nice products. If you want ease of cleaning your optics, consider the LensPen and LensPen miniPro. Available from camera stores and the mail order dealers you are likely to see mentioned on this ETX site.


Subject:	Re: Cleaning the Corrector Lens
Sent:	Monday, May 21, 2001 04:33:55
From: (Clay Sherrod)
First the lens pen is NOT a good way to clean neither the corrector lens
nor the eyepieces; the chemicals inside are not good for the coatings
and they leave significant streaking and films.  Mix a gallon of
solution using three quarts of distilled water and one quart isopropyl
alcohol and one large teaspoon of Ivory (ONLY!!) liquid dishwashing

You apply this with ONLY Kleenex brand (it is made of cotton,not wood
fibers) tissue.

Use this generously on the corrector by applying to the Kleenex (never
to the corrector lens) and rubbing gently; you should have enough liquid
to keep it from drying out; quickly use a dry second Kleenex to very
gently rub to loosen particles and stubborn stains; a third dry Kleenex
is then used to polish or buff the lens (very lightly!).

The same procedure should be used for eyepieces and your finder, rolling
up the Kleenex into a "pen" point to get into the difficult crevaces.

Clay Sherrod
-----Original Message-----
>Could you reiterate your method for cleaning the corrrector lens, as well
>as eyepieces, lest we have the urgent desire to do so? I have an ETX-90/EC
>that could use a better cleaning than what the Carson LensPen does. I
>believe you said you didn't like the LensPen, so I'm looking for an
>alternative method.


Subject:	TECH TIP - ETX 125 finder and cleaning precautions!
Sent:	Tuesday, May 29, 2001 15:11:33
From: (Clay Sherrod)
As part of the ETX Supercharge Service, I always check, clean and
collimate the finderscope of all telescopes sent to the Observatory.  In
most cases, the finders are typically cleaner than the telescope itself
but frequently need collimation, particularly the right angle model used
with the ETX 125.

Another major problem with the ETX 125 right angle finder is GREASE
deposits on the eyepiece lens.  Almost every one that I see has it.


Because the finder is focused via the small helical rack below the
eyepiece and this gearing is packed with a very thick and viscous grease
for smooth focusing and also for holding the focus once achieved.  This
grease is very abundant under the rubber eyecup and ETX users typically
smear this when cleaning.  This grease contains petroleum distillates
which are VERY difficult to clean and are very harmful to the magnesium
fluoride coatings on the eyepiece lens if left uncleaned.

Thus, I have a simple tip for ETX users who have the right angle
finderscope.  REMOVE THE RUBBER EYECUP prior to attempting to clean! 
Most of the grease that is smeared across the lens is from an
accumulation UNDER that eyecup, and if the lens is rubbed with the cup
in place, it is pulled out from the crevace and onto the glass surface.

When a telescope arrives that has the grease on the finder (and nearly
all do), I typically will use a special solution that has about one-half
isopropyl alcohol to one-half distilled water with some Ivory liquid,
rather than the 1/4 part iso. to 3/4 water that is typically used to
clean other optical surfaces.  I have found that this will break the
film easily and prevent excessive rubbing on the fine glass surface in
an effort to remove the film.

P. Clay Sherrod
Arkansas Sky Observatory
ETX Supercharge Tune Up Service


Sent:	Tuesday, June 25, 2002 1:13:11
From: (Clay Sherrod)
The "new" cleaning solution formula AND technique is posted
(temporarily) on the Arkansas Sky Observatory website under "Current
News." It will hopefully be moved under our GUIDES section when time

You will find the heading under:

Note TWO things about this cleaning solution/process:

1) there is nothing "magic" or earthshaking about the final cleaning
solution.  I tested all current recommended methods and learned (and
groaned....) from those; many worked okay, while others failed
miserably. Some were NOT safe for EMC much less UHTC coatings...some
seemed to work on Starbright while failing on other types.  This
concoction is your "kitchen variety" in that EVERYONE can put this
together and make it work....and boy does it work well.

2) the TECHNIQUE is just as important as the proper cleaning solution. 
If you will follow both the recipe AND the proper cleaning process to
the letter, you will have very good and streak-free results without any
hassle whatsoever.

Pay attention to the TIPS that I have provided; these are small
considerations that make a HUGE difference in cleaning of your optics.
Please read ALL information before attempting to clean optics and


Best of luck, and the most in shiny glass!
Arkansas Sky Observatory


Sent:	Thursday, June 27, 2002 5:53:52
From: (Clay Sherrod)
There seems to be some confusion and difficultly in obtaining the proper
cotton pads to clean corrector plates, lenses and all refractive optical
surfaces with.

Please follow to the letter the ASO Cleaning Protocol as outlined at:

Regarding the cotton pads, if they leave LINT, you are NOT using the
right stuff.  I have found the actual one-and-only source of these
wonderful cleaners!


"4 x 4 ESTHETIC Gauze lint-free, 4-ply, opens to 8" x 8", non-woven"

"Non-woven, medical-grade wipe ensures lint-free application and removal
of a variety of esthetic products"

Barnhardt Mfg., Charlotte, NC

That should do it!  Ask your pharmacy to ORDER IT for you!  Or just call
the number given above!

Dr. Clay

Subject:	Lens Pen Warning
Sent:	Thursday, July 18, 2002 22:08:31
Thanks for maintaining and sustaining this site. It was integral in my
decision to buy an ETX90 RA and is the first place I go for scope info.

I bought a LensPen about three months ago and have used it a few times
with generally good results. Yesterday I was noticing how dirty my moon
filter was and decided to touch it up with the LensPen. I was attempting
to gently clean the filter when I noticed that not only wasn't the
filter coming clean, but it was getting smeared and streaked. After
closely inspecting the pen I noticed that the soft pad on the end of the
pen had detached (it was still in the cap) and I was rubbing the black
rubber underneath against the filter.

A word of caution to anyone who uses a LensPen: Always inspect the thing
before you let it touch any of your optics, the tip is black and it is
not obvious if the pad has fallen off. I will now try to rehab my poor
moon filter. I guess I should look on the bright side, if I must ruin
something in my eyepiece case than I'm glad it was an inexpensive moon
filter and not an expensive eyepiece or even my scope.

BTW I really enjoy the ETX90RA I believe I bought the perfect backyard
scope for a beginner. Living in Las Vegas I must contend with some of
the most light polluted skies in the country (if not the world). As
such, I seriously considered buying an ETX90 EC reasoning that I would
never be able to find anything dimmer than the moon in my sky without
the Autostar. It takes some work, but with the help of Starry Night
Backyard on my PC and my Scoprtronix 40 mm eyepiece I'm finding
everything I look for and enjoying the search. Again thanks for the
great site.

Mike Silverman


Subject:	lens cleaning
Sent:	Monday, July 29, 2002 16:10:31
From: (a.hatwood)
I've owned my ETX 125 for around 2 years. Apart from the occasional blow
from an air can, the front lens has never been cleaned. Every thing I
have read about cleaning optics, says "Don't Do It" unless the optics
are really dirty.

My problem is how do you define dirty? My lens looks pretty mucky to me,
but with nothing to compare it to, it's hard to say.

Could you or Clay take a look at these photo's, and let me know what you
Tony Hatwood.
dirty optics
Mike here: That amount can cause "light scattering", which can affect performance. Personally, I'd clean it.


From: (Clay Sherrod)
Oh, yes absolutely....but first it needs to be brushed off very gently
with a soft artists' brush to remove the debris that I can see on
it....then cleaned.

My new solution under "Guides" at the ASO site is by far the best I have
seen, provided that it is used to the letter as described in that new
report.  It makes cleaning a snap and is near-perfect.

Dr. P. Clay Sherrod
Arkansas Sky Observatory


Subject:	Re: Fwd:  Re: lens cleaning
Sent:	Saturday, August 10, 2002 7:21:39
From: (a.hatwood)
I've been collecting the materials I need to make Dr. Clay's magical
potion, and I have a couple of questions.
1. I can only get de-ionised water, as opposed to distilled. Is this suitable?
2. I live in the UK. Do you know if Windex (blue) is available here? If
not, do you know of a British counterpart?
Sorry to be a pain, but I'm determined to get this cleaning process
Thanks again,
From: (Clay Sherrod)
you CAN use deionized water as a substitute, but it MUST be filter prior
to using on optics;  a standard coffee maker filter will work
fine.....just take your time and filter about a quart which will last
you for a long time; the Windex solution -must- be used as is....

Following is the formula and specification from the actual chemical
company that does their testing:

Dr. Clay


NSN: 793000F040924
Manufacturer's CAGE: 85234
Part No. Indicator: A
General Information
Company's Street: 8600 GOVERNORS HILL RD STE 300
Company's City: CINCINNATI
Company's State: OH
Company's Country: US
Company's Zip Code: 45249-5000
Company's Emerg Ph #: 513-583-3900/800-242-1677
Company's Info Ph #: 513-583-3900/800-242-1677
Record No. For Safety Entry: 001
Tot Safety Entries This Stk#: 001
Status: SE
Date MSDS Prepared: 22APR92
Safety Data Review Date: 12JUL95
Preparer's Company: DRACKETT PRODUCTS CO
Preparer's St Or P. O. Box: 8600 GOVERNORS HILL RD STE 300
Preparer's City: CINCINNATI
Preparer's State: OH
Preparer's Zip Code: 45249-5000
MSDS Serial Number: BXMRC
Ingredients/Identity Information
Proprietary: NO
Ingredient Sequence Number: 01
Percent: <3
NIOSH (RTECS) Number: NT8050000
CAS Number: 67-63-0
Other Recommended Limit: 400 PPM
Proprietary: NO
Ingredient Sequence Number: 02
Percent: <2
NIOSH (RTECS) Number: KJ8575000
CAS Number: 111-76-2
Other Recommended Limit: 25 PPM (SKIN)
Physical/Chemical Characteristics
Boiling Point: 212F
Vapor Pressure (MM Hg/70 F): 17.6
Vapor Density (Air=1): 1.2
Specific Gravity: 0.99
Evaporation Rate And Ref: (BU AC =1): 0.3
Solubility In Water: COMPLETE
pH: 11
Fire and Explosion Hazard Data
Flash Point: 129F
Flash Point Method: SCC
Reactivity Data
Stability: YES
Cond To Avoid (Stability): HEAT, FLAMES.
Hazardous Poly Occur: NO
Health Hazard Data
Route Of Entry - Inhalation: NO
Route Of Entry - Skin: NO
Route Of Entry - Ingestion: NO
Health Haz Acute And Chronic: EYES: IRRITATION.
Carcinogenicity - NTP: NO
Carcinogenicity - IARC: NO
Carcinogenicity - OSHA: NO
Explanation Carcinogenicity: NONE
Signs/Symptoms Of Overexp: SENSATION OF IRRITATION.
Precautions for Safe Handling and Use
Control Measures
Transportation Data
Disposal Data
Label Data
Label Required: YES
Label Status: G
Label Street: 8600 GOVERNORS HILL RD STE 300
Label State: OH
Label Zip Code: 45249-5000
Label Country: US
Label Emergency Number: 513-583-3900/800-242-1677

Subject:	New Cleaning Pads
Sent:	Wednesday, August 28, 2002 04:42:43
From: (Clay Sherrod)
Our friend at Pacific Sky Observatory, Jim Phillips, has found an
excellent source of COTTON PADS for cleaning corrector plates and other
lens/optical systems.  These pads are a wonderful solution, totally lint
and streak-free according to his tests, to the method and cleaning
solution that I worked on and posted a couple of months back on the
Arkansas Sky Observatory site and that many of you have been using to

If you remember, most were having a tough time finding the cotton pads
here from any source.  These ones that Jim has found are excellent and
nearly the same is his information:

>>>  "It's a US company in business since 1905.

"Sentinel Consumer Products
7750 Tyler Blvd.
Mentor, OH 44060

"The product on the top left (white pads with the green "80" on the
bag)is the one I have.  Exactly that packaging.  They describe them as
"textured" pads, but it's more like spun cotton batting.  Very soft and
absorbent." <<

Dr. Clay
Arkansas Sky Observatory


Subject:	The ultimate lens brush....
Sent:	Wednesday, September 25, 2002 9:31:40
From: (Clay Sherrod)
Hello to all....
After months of searching and many inquiries about proper brushes for
corrector plates and MAK front lenses, I have found and tested the
ultimate brush.

What's can get it a Lowe's Home Centers....

This is an incredibly soft brush with no bristles hard enough to both
even the softest of finishes.  I have been using one now for about 4
months to test on refractors, Newtonian mirrors, corrector plates and
all other optical surface;  I did a long-term "scratch test" using some
very soft sprayed lacquer that would sleek over long periods of rubbing
should the bristles be too stiff.

None.  Perfect results.  The brush will be ideal for coated, uncoated,
special coatings, UHTC, EMC, lenses, mirrors, front surface silvered
mirrors.....virtually everything with a large enough surface area to
clean with them.

Here are the details on the brush:  (run....don't get one of
these; you will be amazed at how effective this little brush is for
picking up crud, dust and pollen from your corrector plate...FAR softer
than the StaticMaster anti-cling brush.  I have put my StaticMaster in
mothballs because of this neat little brush!

1) small brush with flexible rubber short handle, 2" wide with finely
tapered bristles; very easy to hold and maneuver around the edges of
your front lens;  the soft easy grip handle is ideal for telescopes as
it is nearly impossible for the brush to slip out of your
also is so short that you can really turn the necessary surfaces to
clean optics.

2) found in Lowe's paint brush department, near the fine quality trim will by far be the "shortest" brush on the hanging rack;

3) look for a blue and yellow package with a yellow soft handle hanging
out the bottom;

"Wooster Shortcut" brush, 2" - (Oil paint and varnish, white china
Distributed by:
Wooster Brush Co.
Wooster, Ohio, 44691 and Reno, Nevada 89510

Dr. Clay
Arkansas Sky Observatory


Subject:	Telescope Optics Cleaning Pads
Sent:	Saturday, November 2, 2002 10:23:29
From: (Clay Sherrod)
Hello to all.........
I have found a source for the cotton cleaning pads we have all been
looking for (well, not me....I have several cartons of them)
These are the Esthetic Wipes by Barnhard Industries that have been
searched out....

The long search for a reliable source for the non-woven ultra-soft
cotton cleaning pads that I have found to be the ideal cleaning medium
for astronomical lenses, corrector plates, eyepieces, camera lenses and
binoculars has now found a source willing to sell direct to the
astronomical community at very reasonable pricing.

I contacted the manufacturer and turns out the Bobby Barnhard, of
Barnhard Industries is also a very enthusiastic amateur astronomer and
supportive of our efforts, so he had his marketing staff supply the
following source.

Note that these are absolutely lint-free and scratch-free cotton pads,
4" x 4" and suitable for all fine optics.  They are the ultimate is safe
and streak free cleaning if used in conjunction with my new formula and
procedure posted at the ASO site under "Guides"
( )

Following is the response from Barnhard's marketing director:

------------[begin quote]:
"Dr. Sherrod,
I apologize for the delay in getting back to you; however, I wanted to
secure a supply source for you and your colleagues before responding. 
And I have done just that!  Our leading distributor, The Nailco Group,
has a division called Sunco that is ready, willing and available to
supply you and your associates with our 4x4 Esthetic Wipes.  Maureen
Mann, whom I have copied on this e-mail, is the sales manager for The
Nailco Group.  She and I have discussed your needs, and you can / /
contact her via e-mail ( or telephone [...]

I am so pleased to learn of yet another professional use for one of our
quality products.  I appreciate your leadership in putting us in touch
with your colleagues and feel quite comfortable that you all will be in
very good hands with Maureen and Sunco.  Do not hesitate to contact me
if I may be of further assistance.

------------------"  [end quote]

They have indicated their willingness to sell direct for reasonable
orders to consumers worldwide (I would assume that we would all have to
pay appropriate postages....) OR give us the source closest to your

I am calling on Monday and setting up some details on being able to get
these to at least ONE (hopefully more around the country will contact
them as well....) top dealer that I would like to see carry these pads
for telescope and optical cleaning purposes.

Dr. Clay


Subject:	etx 125 flip mirror cleaning
Sent:	Thursday, May 29, 2003 15:16:28
From: (dan hester)
Thought I would pass along some information about cleaning the flip
mirrow on an etx that will probably make you and Dr. Clay cringe.

My flip mirror was very dirty...pollen, dust, a haze had formed on the
mirror.  Something had to be done.

After much thought, here's what I did.

1. Carefully drilled a quarter inch hole in the bottom of the plastic
housing at the rear of the scope for drainage.

2. Mixed distilled water, a tiny drop of dishwashing liquid and small
amount of alcohol.

3. Used the focus knob to move the main mirror as far forward as

4.  Armed with cotton balls...a small pair of tweezers, one clean
container with the solution and another small squeeze bottle with pure
distilled water...i went to work.

5.  Attached cotton ball to tweezers, turned the mirror to an almost
straight up position, used a small bulb to blow off dust.

6. Dipped the cotton ball in the solution and carefully lowered it onto
the mirror...being careful to use only the weight of the wet cotton ball
on the mirror while the ota was pointed almost straight up (for

7. After several passes with the cotton ball (carefully)...i used the
small squirt bottle to gently squirt distilled water to wash off the
solution.  All the water drained out the small hole I had drilled.

8. I attached an absorbent lens cloth to the tweezers and let it lie
only with its own weight on the mirror to remove excess water.

9.  I let the unit air dry with the OTA pointed up...then put a small
rubber plug in the hole.

Bottom seems to have worked very well.

The mirror is spotless, no scratches and no water got inside the scope.

Maybe it's a little crude, but if it works, it works.


Subject:	Cleaning Optics
Sent:	Saturday, November 8, 2003 02:20:24
From: (Stephen Bird)
To: (P. Clay Sherrod)

In the UK it is impossible to get Windex. The common glass cleaner over here
is Windolene, the product is not the same, being a clear rather than blue
liquid. This means that making your ASO Superplus lens solution a little
difficult, as I am unable to get an alternate cleaner where I can confirm it
as being the same as Windex. Some of the supermarket brands do look the same
as Windex, but I am unable to find out from SC Johnson who make Windex if
they allow the supermarkets to either re-label windex or manufacture their
own brand under license.

Chemically Windolene aims to do the same thing as Windex, but the components
are different:

Windex = Ethylene Glycol n hexyl ether (1% approx) + Isopropanol (5% approx)
+ Water (95% approx).

Windolene = Butoxypropanol [also called Propylene glycol monobutyl ether)
(5% approx) + Sodium Hydroxide (less than 1%) + Water (95% approx)

With the exception of the propanol (which being alcohol is part of the other
ingedients of the lens solution anyway) the components are very similar,
except of course that sodium hydroxide is listed, whereas in Windex the only
mention is the "smell of ammonia".

In your opinion would it make much difference if Windolene was submitted in
place of Windex in the cleaning solution? What concerns me is the inclusion
of (less than 1%) ammonia in the composition of Windolene.


Stephen Bird
From: "P. Clay Sherrod" (

Please pass this on to others in the UK...

Windolene is excellent, except you need to make one change in the
formula to account for the difference in composition: Decrease the
amount of Windolene per quart mixed (or whatever volume) by 25%
overall....that will make up for the change of the alcohol content; note
that Windolene does not contain any vinegar, but does contain some
degree of ammonia....that is what you want.  Avoid any cleaner for
coated optics that has acetic acid (vinegar) as one of its components.

Good luck and thanks for writing.

Dr. P. Clay Sherrod
Arkansas Sky Observatory
Harvard MPC H41 (Petit Jean Mountain)
Harvard MPC H43 (Conway)
Harvard MPC H44 (Cascade Mt.)

Mike here: As discussed by Dr. Clay Sherrod and others above, Dr. Clay's cleaning solution and techniques are excellent for cleaning your optics (not mirrors though). Oceanside Photo and Telescope has bundled everything you need into a kit. You can read my review at: "OPT Doctor Clay's Cleaning Kit".

Subject:	Re: Question on Use of Dr. Clay's Cleaning Kit on ETX
Sent:	Friday, May 23, 2008 13:28:34
From:	P. Clay Sherrod (
On this mirror there is NO protective overcoating, so you must be very,
very careful; I suggest using only a brush to clean off the surface and
use it very delicately.  Using compressed air will blow the dust inside
the OTA which just creates even more problems.

Sometimes if you rub a square tipped artist's brush rapidly against a
nylon or synthetic cloth (a clean shirt) back and forth many times, it
will build up enough static charge to attract the dust particles and
actually remove them from the OTA!

Best of luck...

Dr. Clay
Arkansas Sky Observatories
Harvard MPC/ H43 (Conway)
Harvard MPC/ H41 (Petit Jean Mountain)
Harvard MPC/ H45 (Petit Jean Mtn. South)

----- Original Message ----- 
Subject: Question on Use of Dr. Clay's Cleaning Kit on ETX

Dr. Clay-

I have your optics cleaning kit and had a question of proper use.

I purchesed an ETX-90PE as a store demo. I think the eyepiece hole was
uncovered at some point-- there is dust on the right angle mirror.

What would be the proper proceedure to clean the right angle mirror?
Your great instructions talk about different cleaning for "protected"
versus "non-protected" mirror surfaces. Wasn't sure which the right
angle mirror was.

- Use a small brush or air can? (didn't want dust going free and
possible up to main mirror)

- Your cleaning solution and extra long Q-Tips?

This would be just a one time thing. Once clean I'd leave in covered.

Thanks so much for your help! Am looking forward to having you
supercharge both my scopes when in budget.



----- End Original Message ----- 

And an update:

Thanks Clay!
What looked like grime just came off with a light brush or two on the RA
mirror with an artist's brush, and putting a static charge on it with
polyester also seemed to work.


Thanks for the great site as well.  I also have a new LX-90.  Maybe your
site can expand to that since you just got one.


Excellent and thanks for the update.

Dr. Clay

[11/16/10] [NEW!]
Subject: Using Windolene for cleaning Telescope optics
From: Brian (
To: (Stephen Bird)
Sent: Monday, November 15, 2010 5:41 PM
Hi Stephen,

I got your details from the Mighty ETX site. I am desperately trying to
find a substitute for Windex, and note that you have had the
conversation with Doc Clay about using Windolene.

Which version did you use? I have seen lots of cautions on camera sites
warning that the pink stuff contains abrasives. I assume you used the
clear stuff. I haven't actually been shopping for it, because I didn't
realise that there were two versions and my years old experience of
using the pink stuff for cleaning various things (like aircraft cockpit
canopies; don't ask) always seemed to end in tears. Mostly mine!!

If you used the Windowlene, what were your results like?

Any help greatly appreciated as my 12" LX 200 GPS is about to burst into
bloom it has so much pollen on it.

Best regards,

Brian Martindale


From:	Stephen Bird (

DO NOT use Windolene or any of the UK look-a-like Windex products. All
of them contain either abrasives or other non friendly chemical
additives that will wreck the coatings on your optics as far as I know.
Even though people tell you they are the same, in my researched opinion
they are not.

In fact Windex is made by SC Johnson a US company. Windolene used to be
made by Johnson & Johnson, but it was always a complicated relationship
and they never made Windex in the UK. Windolene is now made by Reckitt
Benckiser who I think bought out J &J a few years ago. Complex eh! SC
Johnson do produce products for the UK market under the "Mr Muscle"
name, but not a Windex equivalent that I have been able to find.

I pulled the specification sheets on a few of the products that looked
promising and none were the same as the good old Blue Windex.

So in the UK this gives you a problem. I solved this by bringing a
supply in from Australia as I visit every three years and my relations
do vice versa. So each time I go I grab a 500ml bottle or get a relative
to bring me one over. I get really nervous these days as even though it
goes in the hold luggage, we all know what it looks like. Anyway I'm
sitting on 2 litres of the stuff, so with Dr Clay's recipe I am set up
for life. You have to mix it exactly as he says, and boy does it work
great! I use it on the house windows and the car glass too!!

As to importing it via post, I have a feeling it would not get through
the current freight checks, but with Christmas coming up you might be
lucky. Shame I had a friend just back from the land down-under only a
couple of weeks back and the standing joke of what to bring me as a
present came out:-)

Time to check out friends and relatives in far off places for you I


Stephen Bird


I just got back from the supermarket. It's not good news I'm afraid!

The blue Windolene contains VINEGAR and thus is NOT suitable for use in
the Doc Clay cleaning system. I never got to read the rest of the
ingredients, it says right across the front label 'Cleans with Vinegar!'

Also, the listing of ingredients in UK is not as stringent as it is in
the US. Some cleaners say 'Contains, among other ingredients....'

God knows what is in them!

The Windolene that Doc Clay endorsed was either a different version of
the product or an old recipe; the post was dated 2003.

Back to the drawing board on this one unless someone from UK comes up
with the answer for me.

Regards, Brian


Apologies, it was Johnson Wax, not Johnson and Johnson! I have been
working on a pharmaceutical contract the last couple of months and J & J
was on my mind. Johnson Wax was the UK arm of SC Johnson a good few
years back. SC Johnson are still in the UK, but Windowlene is not made
by them. All very confusing!

Anyway Windex Original is the one you want:

Stephen Bird

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