Dave....That was a great post. I wonder who JJ was. However... I'm a little suprised about having to use the alcohol. First, if you do your final rinse with distilled water, the mineral content should be very low, and not leave spots upon drying. Also, I've found that if I've done a good job of cleaning, the final water rinse sheets off almost completely, with just a few drops left here and there. These I absorb with the tip of a paper towel. Just another opinion. .....RICH
--------------------------------------
Date: 4/5/95 3:54 PM
To: Richard Combs
From: atm@best.com
>
> My shiny new mirror is getting dusty and dirty. I tried blowing some
> canned air on it to clean it off and ended up with a blueish haze where
> the air hit the mirror. I intend to take the mirror out of the mount,
> soak it in a bathtub with a little dishwashing soap, then rinse well
> and wipe lightly with lens cleaning tissue and Edmunds Sci. lens cleaning
> solution. Will that take care of the blue haze from the canned air?
>
> PS -
> We've been having network problems here. Sorry if you've seen this -
> I don't know if we dropped the copy I sent or the one I got back from
> best.com.
>
> Bob
I have never tried this procedure, but I got the following off the net a couple months back. Caveat emptor!
-Dave
I've used several cleaning procedures recommended by magazines and books, but I always get to that step where there are still beads of distilled water on the mirror that won't drain off, and I'm helpless as I watch them slowly dry up, seemingly taking forever. I developed this new procedure and my mirror gets perfectly clean, and spot- and haze-free.
Note: Cleaning a mirror is a very personal thing. I have used this procedure with great success, but this is, of course, a very limited sample. Do only what you think best for your particular circumstances. For example, if your mirror is still under warranty, as mine is, follow the instructions in the owner's manual as to materials and mixture concentrations.
Mirror size: I'm assuming a 4-13" mirror. Adapt for larger sizes.
Frequency: If something is not necessary, it is best to refrain from doing it. A good guideline is to never clean the mirror, and go from there.
Cleaning the mirror is like chinese cooking. Everything must be ready to use and the action must be continuous with no interruptions. Turn off the phone and lock the door. Perform the following steps with no pauses during or between steps.
Get ready the following materials and equipment (or equivalent):
Absorbent cotton, 100% USP sterile, 2 oz. roll Dish soap, Dawn clear (appropriate name, isn't it?) - has no perfumes or dyes. Distilled water (de-ionized), 1 gallon Isopropyl alcohol, 91% Hair dryer - heating element OK but not preferable Turkey baster, glass or one with a good air stream - look in the Yuppie utensil store in the Mall
1. Blow off the mirror with the baster; you probably don't even need to clean it. If you still think you must, then remove the mirror from its cell.
2. Run a light stream of water in the sink to room (and mirror) temperature and place the mirror under the stream at a slight angle, propped up on a hand towel or large sponge so the water runs fully across it and down the drain. Always beware of that faucet: it's a killer. Wet a medium-sized piece of cotton and apply a little dish soap. Waft the cotton in back and forth strokes over the entire surface. (Waft means to lightly move as if on a buoyant medium - look it up.) The running water will gradually rinse the soap from the cotton as you do this but that's OK. Squeeze out and discard the cotton, and either repeat or go ahead and rinse the mirror thoroughly. Trying to rinse the back of the mirror is where a mishap can occur. It is not necessary to turn the mirror over to rinse the back so let's avoid it altogether. Make sure the front is fully rinsed of soap by wafting another wad of cotton without the soap this time. Rinse some more.
3. Turn off the water and tip the mirror up almost to the vertical this time, watching out for that faucet. Pour the distilled water onto the top edge of the mirror and down the face of the mirror. This displaces the high-mineral content water that would permanently spot the mirror if allowed to dry. Pour just enough distilled water to give it full coverage. Splashing is OK, it helps rinse the back.
4. With the mirror still at a steep angle, slowly and carefully pour alcohol down the face of the mirror. (Use either full strength 91% alcohol, or the alcohol/distilled water mixture recommended in your particular owner's manual (usually 50/50). This displaces the slow-drying H2O. Remember alcohol is a solvent. Do not get any on the back of the mirror as it will erase or smear any markings or QC stamps there. The trick is to get FULL coverage on the front yet don't get any on the back. I use an absorbent washcloth as a dam and the baster to squeeze alcohol on the extreme upper portion of the mirror, and then pour from the bottle to get the rest.
5. Follow this quickly with the hairdryer on high speed from about three feet away. Waft the air! If you catch the light just right, you will see the evaporation line race across the face of the mirror, leaving a perfectly clean, dry, spot- and haze-free surface.
I have submitted this procedure to both S&T and Astronomy, but neither magazine has found room for it yet (chickens). Well, it works for me.
QUESTIONS:
1. Is alcohol bad for mirror coatings? A: No, it isn't. Your type of coating was specifically tested to a solvent specification and passed. You would have heard of anything bad by now, anyway. All sources (books, magazines, manuals) say to use it. It is specified in owners' manuals, and we are talking thousands of mirrors. The variable here, however, is the concentration tion of the alcohol/distilled water solution. Some sources (Meade for one) say 50/50, some say 90/10, some say 0/100. Some are vague, specifying an alky/H2O ratio, but not giving the type/conc. of the alcohol itself. Rubbing alcohol says it is 70/30 (but read the label, some rubifacients contain mineral oil or glycerin). And then there is denatured alcohol at 95%. If I were to change my procedure, I would probably go to to the much cheaper 70% isopropyl alcohol, as long as I was sure the inert ingredient was purely distilled water. Anyway, this is where the research needs to be done. What is the minimum alky/H2O ratio that still gives rapid evap. with blowing air? I will use it.
2. How often should I clean my mirror? A: Normally, as far as a vacuum-deposited reflective optical coating less than a micron thick is concerned, if something is not necessary, it is best to refrain from doing it. A good guideline is to never clean the mirror and then proceed from there. However, city- <|,"3">dwelling and seashore telescope mirrors actually benefit from a periodic (4-6 mo.) removal of pollutants. This can extend the life of the coating. Some specialty coatings, like Beryl, are really tough stuff, though, and you can leave them out in the rain (well, not quite).
3. What about mirrors larger than 13"? A: A 10" fits in the bathroom sink. A 13" fits in the kitchen sink. Some 16-to-20-inch mirror owners have been known to get right into the bathtub with them. Over 20" hey, ask the man who owns one.
4. Should I use canned air, alcohol swabs, lens cleaner, lens tissue, lens brushes, facial tissue, cosmetic (synthetic) puffs/ pads, acetone, or sulfuric acid on my mirror? A: No.
5. What happens if water is allowed to dry on the mirror? A: Permanent polka-dots.
6. What happens if I do accidentally drop the mirror? A: ... Then disregard the above procedure. Actually, recoating a mirror is really inexpensive - replacing a mirror is not. Most of the labor cost in a telescope goes into machine- and hand- figuring of the mirror blanks. Making a mirror takes from dozens to hundreds of hours, depending on the size of the blank, the pocketbook of the consumer, and the standard of quality of the manufacturer. It has somehow been determined by the mass-producers that 1/4-wave is a good qual/cost ratio. Let's not get into another controversial (p-v, rms?) area here, however.
DISCLAIMER: This cleaning procedure is solely my opinion and will most probably ruin your mirror completely and you will have to get it recoated/replaced at your own expense. Everyone will laugh at your foolhardiness for believing something that you read on the Net. There. I am totally disclaimed.
Goodbye.
JJ
------------------ RFC822 Header Follows ------------------ Received: by quickmail.llnl.gov with SMTP;5 Apr 1995 15:51:59 -0800 Received: (majordom@localhost) by shell1.best.com (8.6.11/8.6.5) id OAA26662 for atm-outgoing; Wed, 5 Apr 1995 14:36:45 -0701 From: David Boll <dboll@hp-vcd.vcd.hp.com> Message-Id: <9504052136.AA12975@hp-vcd.vcd.hp.com> Subject: Re: Cleaning mirrors To: atm@best.com Date: Wed, 5 Apr 95 14:36:54 PDT In-Reply-To: <9504052054.AA23318@db1.ncube.com>; from "Bob Bond" at Apr 5, 95 1:54 pm Mailer: Elm [revision: 70.85] Sender: owner-atm@best.com Precedence: bulk Reply-To: atm@best.com