The
Arkansas Sky Observatory’s Dr. P. Clay Sherrod has produced on its
webpage an excellent guide
for
cleaning your eyepieces and other refractive glass (corrector plates,
etc). He recommends making your own excellent quality cleaning solution
and rinse solution. A pamphlet with his guide is available as a pdf
file. Dr. Sherrod
designed this cleaner with the Meade UHTC coatings and the Celestron
XLT coatings in mind. Note that there is now a link in that guide
to Dr. Sherrod's method for cleaning 1st surface mirrors.
There
are some wild claims on the internet about eyepiece/refractive surface
cleaners.
-->A
few folks use acetone...which will remove your paint and any adhesives
holding your lenses together along with the dirt. Don't do it!!!!
--> Some folks
recommend lots of
alcohol...and that will loosen any adhesives in the area too.
Don't do it!!!!
--> Straight
Windex has a pH of
10-11 due to the presence of ammonia which will wreck your
coatings. Don't use it !!!!
--> A lot of
the $3.50 cleaners
are similar to ours, but stored in polyethylene or polypropylene.
These plastics are know to be permeable to alcohols, but not
water. Check the weight of your container every week and you will
see it getting lighter as your isopropanol or other alcohol leaves
through the sides of the container. If you buy this, be sure to
use it quickly... We store ours in polyethylene
terephthalate, a more expensive bottle but not permeable to alcohols.
--> The
fact is Dr. Clay
Sherrod knew what he was doing. There is just enough windex in
his formula to get the benefits of the formula while keeping the pH at
8. It has enough isopropanol (some from the Windex) and some
added to clean the glass without hurting anything else. Dr. John
Duchek (me) came along and found the proper storage to make the alcohol
and other ingredients stay in the container. I filter all of the
ingredients, mix them and refilter them into the individual
bottles.
--> One company
that sell a similar cleaner is proud to use 99% isopropanol. That
sounds nice, but you don't how it was processed. The great thing
about
the 91% material is that the final step in purification is VERY LIKELY
to be distillation. The 91% isopropanol 9% water is what chemists
call
an azeotropic mixture. If you do a careful distillation, it is
the
ratio you get no matter what the ratio of water/isopropanol is when you
start. Having the final step be distillation is very comforting
because that means everything in the mixture is volatile. When
the mix
evaporates, there is nothing left behind. If you are cleaning
lenses,
that is a good ingredient! In processing we do take the 9% water
into account so that the concentrations in the cleaner are correct.
For
all of these reasons, we are proud to say, "invented by an Astronomer,
prepared by a Chemist"
Here
is the value I add to this product:
- 1.
The
containers have
been tested for compatibility with the formula.
There are problems with containers of polyethylene and polypropylene.
These are permeable to isopropanol and with time the alcohol leaves and
the water stays...and the formula changes.The bottles
(polyethylene
terephthalate --PET) and spritzers I use have been tested and lose very
little material over long periods of time. PET bottles are more
expensive than polyethylene ones.
- 2.
My version of Clay's formula is
filtered twice using Whatman grade 541 laboratory filter paper. This
has 19-25 micron pores which are quite a bit finer than the "coffee
filters" recommended on Clay's site. The bulk solutions are filtered
once, and the final product is filtered into the bottle. That coupled
with an initial filter paper cleaning step ensures that very few
"floaters" (loose fiber from the filter paper) appear in my product.
- 3.
Rather than mixing one ounce of this and one-half ounce of that, I
converted the formula to metric and measure the ingredients to a single
milliliter (1/30 ounce). After my formula was passed by Dr. Sherrod to
be certain I had it right, this accuracy and precision and a specific
gravity test on each batch ensures that your bottle is just like the
bottles that Clay approved.
Does
the brand you are buying tell you how it is processed?
NOTES:
The ASO cleaner/rinse is a great formula when made and stored
correctly. It is the right stuff to clean your eyepieces and
refractive glass. It IS NOT the right stuff for cleaning
mirrors. For that you should use straight isopropanol.
A user suggests:
One
of my ASO users said that he would like to get a spritzer bottle to
apply the 91+% isopropanol to some filters with mirror like coatings
that he wanted to clean. That seemed like a reasonable idea for an
additional product, so I sent him one free as a thank you for the
idea. The spritzer bottle is the same PET plastic and spritzer
head labeled for isopropanol use.
User comments!
For
information on the proper use of this
product and for methods for properly cleaning 1st surface mirrors, see
The Arkansas Sky Observatory (ASO) webpage: http://www.arksky.org/asoclean.htm