View Full Version here: : Mirror cleaning
Zander
29-05-2007, 04:32 PM
hi, just a simple question. when rinsing the mirror after having cleaned it. would boiled off rainwater be alrigth to rinse it with??
i had some demineralised water somewhere but can't find it :shrug:
astroron
29-05-2007, 05:01 PM
It should be alright, but I suggest you filter it as any rain that comes of your roof may have dust in it which could scratch your mirror
ballaratdragons
29-05-2007, 05:46 PM
You could distill your own water.
Boil any water (tap, rain, creek) in an open top container with a piece of glass or plastic above it to collect the steam. Then allow the run-off to drip into a clean plastic bottle. :thumbsup:
BINGO! Distilled Water.
My Mum used to do this to make distilled water for her Iron when I was a kid!!! :eyepop:
Satchmo
29-05-2007, 06:03 PM
I just use bulk spring water from supermarket and never noticed any residue after cleaning. I think its only a few dollars for 4 litres. I think th emain thing is piece of mind that the water is filtered and not containing particles of grit and rust from your pipes.
ballaratdragons
29-05-2007, 06:15 PM
If he was going to the supermarket, he may as well just by proper Distilled water, also called de-mineralised water. It's very very cheap! :lol:
Zander
29-05-2007, 06:22 PM
i just got demineralised from the shop :P
but i'm havin trouble with the cleaning of the mirror :(
i washed it as Mike's "how to" said, but there is residue left all over it :S. i rinsed it with the demineralised water but the residue just stays. hte mirror now looks more dirty than it did before cleaning :sadeyes::shrug:
Zander
29-05-2007, 06:32 PM
here are some pics of the mirror. there is a lightish residue left on parts of the mirror :S
astro_nutt
29-05-2007, 09:30 PM
Hi Zander..
Correct me if I'm wrong..but does the lightish residue has a swirl pattern when you shine a light on it?..the reason I ask is that the mirror on my 10 inch saxon developed a hazy swirl pattern on it's surface and you'll notice it only in direct light..but as I've found...this condition hasn't degraded the image.
A simple test for the mirror's reflective coating is to hold the mirror up to a lightbulb and if you can see the structure of the lightbulb's filiment then it might need a reacoat..or test it's image quality against another mirror of the same type..
Have a browse around for other advice..plenty of it in this forum!!
Cheers!
GeoffW1
29-05-2007, 09:39 PM
Hi,
Spring water contains salts of one kind or another doesn't it? I would think you would get a faint powdery residue from it.
Demineralised water is just that - not guaranteed to be free of solid particles like dust.
So I bought DM water from Coles and ran it through a filter paper from the coffee percolator, result was perfect when rinsing a Bintel Dob mirror.
Cheers
GeoffW1
ballaratdragons
29-05-2007, 11:31 PM
Zander,
When you rinsed the mirror off with the De-mineralised water and stood it up on an angle to let the water run off, did you get a paper towel and lightly touch the water droplets to get them off by absorbing them?
If you don't absorb every drop of water on the surface it can leave little water marks similiar to your spots.
Zander
29-05-2007, 11:56 PM
yeah i did all that :shrug:
the swirls seemed to come from the water i washed it in. it was like there was a fine silver powdery stuff in the water. it looked like it was off the bottom of the mirror or sumthin like that. i put in new washing water a few times, but the residue stuff stayed :S. oh well, i dont think it will effect the image quality too much. i'll try to clean it off next time.
wavelandscott
30-05-2007, 08:52 AM
I am strongly in favour of rarely washing mirrors and only when they really really need it.
In my opinion there are 6 possible outcomes when you go to clean a mirror
*Everything works fine and you end up with a clean properly reinstalled mirror
*You get a clean mirror but mess up the reinstallation (or similar mishap)
*You do a poor job cleaning and leave dirt/spots but reinstall poorly
*You do a poor job cleaning and leave dirt/spots but reinstall well
*You clean poorly and scratch or damage mirror and reinstall poorly
*You clean poorly and scratch or damage mirror and reinstall well...
Of those, 5 are "bad"...
Not to be alarmist or scare people because I do believe that mirrors and other coatings were made to withstand some "common" cleaning...but a mirror does not need to be washed weekly or monthly...heck, I don't even clean them annually (unless they need it)...I only do it when they are dirty...it will take a signifigant amount of dust to degrade the view...
It is a sometimes necessary task and when it needs to be done feel confident in doing it...but, a mirror can go a long time before it "needs" to be cleaned (my opinion)
Good Luck All!
Terry B
30-05-2007, 09:31 AM
I agree. I have only cleaned my mirror once in 5 years. I don't see the need to do it any more often.
iceman
30-05-2007, 09:43 AM
I clean mine every 6 months or so, to no ill effect.
I need to do it again, after which i'll put the catseye centre spot on.
Satchmo
30-05-2007, 10:36 AM
Most mirrors used around big cities gather a greasy film fairly quickly. Just breathe on and look at the condensation pattern to see if it has a greasy film .A patchy blotchy condensation pattern, means the mirror is greasy . Also those in bushy setting get a film of Eucolyptus oil which is very tenacious. The mirror surface needs to be soaked in methylated spirits before the normal cleaning process is started. Greasy films and dust scattter light and lower planetary contrast. Small scattered spots of dirt or previous washing blems don't matter.
On the whole most mirrors I have seen get left way beyond the point that they are in need of a good wash for some fear of the unknown. They are all overcoated these days, so you aren't going damage the glass surface of the mirror. IMHO If you like your images clean and contrasty wash your mirror as often as needed, and don't deem it clean unless it passes the breath test.
ballaratdragons
30-05-2007, 11:43 AM
No, they aren't ALL overcoated these days. Some are still manufactured without.
And it isn't the glass that is at risk of being scratched, it's the ultra thin layer of Aluminium. It does mark and scratch very easily. Even fingers leave acid on the Aluminium causing oxidisation. The over-coat is meant to slow down the oxidising.
Satchmo
30-05-2007, 02:18 PM
Yes I should have been more specific .All *commercially* made mirrors are over-coated with Silicon Monoxide or Quartz these days. I don't agree that overcoated surface scratch or mark easily.
Astro -Optical Supplies coating service does not offer overcoat . However a bare aluminium coating will form a hard layer of Aluminium Oxide on top within 3 months which is pretty strong.
Misplaced fear of 'scratching' the coating is a common but poor reason IMHO to have a 'scope with a dirty dusty mirror. Its meant to be looked through not 'at' .
Zander
30-05-2007, 04:49 PM
i didn't know mirror cleaning was such a controversial topic :eyepop:
thanks for the input though, has been most helpful to hear both sides of the matter :)
iceman
30-05-2007, 08:25 PM
ah Mark, a man after my own heart.
Great to finally hear of others who believe that a dirty mirror is bound to reduce contrast and increase light scatter. Cleaning it doens't have to be scary!
That's why I wrote this article (http://www.iceinspace.com.au/index.php?id=63,345,0,0,1,0).
jjjnettie
31-05-2007, 12:23 AM
I do a similar thing but use winewash instead of water.:whistle:
Great for cleaning your ep's.;)
Zander
31-05-2007, 12:54 AM
i tried to distill my own. got about 5 mls for about 30 mins work:lol: :P. mebbe i was doin sumthin wrong:shrug:
ballaratdragons
31-05-2007, 01:16 AM
:lol:
Gargoyle_Steve
01-06-2007, 12:59 AM
5 mls of water for 30 minutes work doesn't sound great - 5 mls of alcohol, on the other hand ......;) that would be a little bit better! You wouldn't waste it on the mirror though if you had that kind of distillation going ok.
back on topic - my local Super Cheap auto accessories place has 4 litres of distilled or demineralised water (not sure which, but it cleans my mirror ok) for less than $4. I haven't seen it cheaper anywhere so far.
Don't use "spring" water - read the label carefully, they are full of various kinds of minerals, etc, and the amunts and types vary hugely from brand to brand.
jjjnettie
01-06-2007, 07:51 AM
Spring water/ Mineral water contain sodium and calcium as disolved solids that will become solids again once the water evaporates.
Satchmo
01-06-2007, 11:04 AM
Don't leave any water on your mirror to evaporate. Dab it off with cotton balls or a bunch of kleenex tissue. I've got an 8" overcoated mirror here thats been cleaned and rinsed under the normal tap for 15 years and it still looks perfect.
ausastronomer
01-06-2007, 11:19 AM
It might be pretty strong, but it still doesn't last very long. The majority of front surface mirrors in professional observatories are bare aluminium coated, not overcoated and need to be recoated about once a year. Overcoated aluminium usually lasts between 5 and 25 years depending on use and environment.
CS-John B
Satchmo
03-06-2007, 12:48 PM
John, I was referring to resistance to scratching after three months rather than ultimate longevity of plain aluminium . It depends very much on how clean the mirror has been kept and where the scope is used. I have seen plain aluminium mirrors that have been kept covered , in remarkeable condition after 10 years. I wouldn't however recommend anybody to get a plain alumium coating mirror these days, no matter how `exotic' a vendor might claim there coating to be.
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