Cleaned filthy mirror - with pictures

[kirkster501]

My mirror was in a bit of a state...

So using the method I have for the last 25 years cleaned it in the sink......

Make sure the sink is clean and there are no cups, plates, glasses etc. about that could drop onto the mirror!  Then run water on it for a few minutes under the tap:

Let the water stand in the mirror for 10 minutes to soften any dirt:

Now using some fairy liquid - a few drops - agitate *gently* the water on the mirror surface with your *clean* fingertips.

Now rinse with RO water (costs peanuts from an aquatic section of garden centre)

That looks better!!!!

Now install back into the scope after letting the mirror vertically dry - can use a few *gentle* dabs with kitchen towel. Never seems to hurt.

 

Job's a good 'un........

[Alien 13]

Nice job, the mild green stuff works wonders 

Alan

[mikeyj1]

nice, to get rid of the last water spots you could/should use distilled water...

[kirkster501]

5 minutes ago, mikeyj1 said:

nice, to get rid of the last water spots you could/should use distilled water...

Yeah, agreed.  However I find RO - much cheaper (and I use it for my tropical fish as well) does 99% of what distilled does.

[kirkster501]

The biggest dangers in mirror cleaning are actually in removing the mirror and carrying it round and the risks of dropping a screwdriver onto it or bashing it into the sink, door frame etc.  The actual cleaning is simple enough.

This mirror is a 12" Dob mirror.  Can clean SCT / RC mirror in the same way.

[mikeyj1]

3 minutes ago, kirkster501 said:

However I find RO - much cheaper

fair point, can't tell that from the tap ;-)

now i see the comment on the jug pic

 

[xvariablestarx]

Out of curiosity, how often do you need to clean a mirror? I have read elsewhere that its a bad idea to judge how dirty a mirror by shining a flashlight down the tube, because it can look filthy but still function well.

[Ben the Ignorant]

Nice cleaning job, nothing pleases a telescopist like seeing clean optics.  My 12" GSO has three clips like your Sky-Watcher, though smaller mirrors often have six clips. The very smallest are always held by three clips only (my 130 and my brother's 150), but I often wondered why mid-size mirrors must have six retainers when some larger ones can do with only three.

I never had problems with my cell, it is stable and strong, but I wonder anyway. I would instinctively put more retainers on a larger mirror if I was designing the cells.

[Ben the Ignorant]

1 hour ago, xvariablestarx said:

Out of curiosity, how often do you need to clean a mirror? I have read elsewhere that its a bad idea to judge how dirty a mirror by shining a flashlight down the tube, because it can look filthy but still function well.

Once a season if you expose it very often to outside air and pollen is present, cause it's quite sticky; every six months or every year if the pace is slower. The flashlight thing is real, intense light scatters on little things and makes them look big, that's why a laser with only 0.005 watt can be seen from the side over very long distances.

I remember a sunny day in kindergarten, sunlight entering between two black curtains made all the dust particles floating in the air so very obvious but they disappeared when they flew into the curtains' shadow. This was one of my first "scientific" observations, maybe the absolute first. I saw the image in my mind again when I read your question.

[Dragon_Astro]

Reminds me, I need to clean the mirror in my 150P.

i dunno how it gets so filthy, when the end cap is always on when not in use. I'm sure the flocking I put inside has something to do with it?

[estwing]

You won't believe how dirty a mirror can be before it affects views...

[mikeyj1]

storing the scope vertically gets the mirror dirtier than horizontal

[Stu]

40 minutes ago, estwing said:

You won't believe how dirty a mirror can be before it affects views...

I know that is the perceived wisdom, but I do find it strange that if you are looking for threshold objects, and you have lost say a few percentage points transmission or are getting a bit more scatter from the dirt on a mirror, surely that must have an impact?

Has anyone done any side by side testing?

[xvariablestarx]

24 minutes ago, mikeyj1 said:

storing the scope vertically gets the mirror dirtier than horizontal

Even if the dust cap is on and the scope is covered in a blanket?

[JG777]

Did you clean the secondary as well? Good tip about the water from the aquatic place. I thought mine was pretty dirty and cleaned it with ionised water and it came out sparkling like yours but even though I thought it was quite dirty it didn't seem to make any difference when I next took it out. I suppose if anything cleaning might help prolong the coatings life. 

[Alien 13]

22 minutes ago, Stu said:

I know that is the perceived wisdom, but I do find it strange that if you are looking from threshold objects, and you have lost say a few percentage points transmission or are getting a bit more scatter from the dirt on a mirror, surely that must have an impact?

Has anyone done any side by side testing?

I agree, people will often cite the fact that you cant see the central obstruction but its not the same thing, a layer of dust scatters light so it must have an effect. I do notice a massive difference when I clean my glasses or windows even if the change in light transmission might be minimal.

Alan

[MarsG76]

Nice and clean....

I'm always weary about touching my mirror while cleaning, so I opt to spray it with distilled water, that isopropyl alcohol and wash it all off with distilled water again and let it dry... touchless cleaning, so far this did a great job.

 

[mikeyj1]

11 hours ago, xvariablestarx said:

Even if the dust cap is on and the scope is covered in a blanket?

Well in my not very scientific test, yes.  I normally store it (the 10" NEWT) horizontally, in a large trunk.  When i needed to to move some stuff around the house and garage, I stopped using the trunk for about 3 months, during which time the scope was stored in the garage vertically, and by the end of that, the mirror was visibly dirtier than it would have been over the same period normally.. Dust cap was always on.  My assumption is that any dust and moisture will naturally settle to the bottom of the tube..

[kirkster501]

Yep, my Dob was stored vertically with a scope cover over it with all caps/covers on it and the mirror was reasonably clean, not pristine by any stretch but not that bad.  And when I used the scope again a year later (not been doing much Dob observing lately) the mirror was in was in that state.

Depends on where the scope is used as to the regularity of cleaning.  If you are observing near trees shedding pollen onto a dewed up mirror then you might need to clean it every few months.  If you're in drier conditions in a hotter country or use infrequently (and we all use infrequently in the UK let's face it due to the climate here), you might need to clean it every two or three years.  Regarding the mirror I cleaned above this is the first time it's been cleaned in five years.  The golden rule is clean as little as possibe.

[Space Hopper]

I cleaned my 10" mirror a couple of years ago, and thought i'd made a bit of a mess of it.

I followed all the procedures correctly, but found the mirrors coatings (OO Hilux) seemed to have a slightly mottled look to them.

I took it over to OO to have inspected. John took a quick look at it, disappeared with it for 5 mins, and returned with it

looking absolutely pristine. I'm assuming it just needed a quick polish, but i'm not sure what he did.

 

My current scope has a 12" mirror, its only 2 years old, and has not had to suffer my clumsy hands yet........

[Ricochet]

I discovered when cleaning my primary that soaking can cause the centre spot to lift so it is a good idea to check it is still centred afterwards. 

[kirkster501]

A common mistake is to try and get the mirror gleaming immaculately without a spec on it.  Not so and furthermore trying to get it to this level of pristineness risks overdoing it and scratching it.  You can get 99.9% of the crud off of the mirror with almost no effort at all. To get that remaining 0.1% (i.e. a few remaining motes of dust and specs) off takes a very great deal of effort and risks causing damage for no real purpose since you'll get those specs of dust on again at the mirror's first outing after the clean.

The mirror clean I did above took 30 minutes - 20 mins of which was the mirror soaking.  It took an hour from mirror in scope and mirror back in scope, cleaned and collimated.

[LukeSkywatcher]

I've had scopes for 10 yrs and never cleaned mirrors. Simply don't need cleaning. 

[kirkster501]

21 hours ago, LukeSkywatcher said:

I've had scopes for 10 yrs and never cleaned mirrors. Simply don't need cleaning. 

Depends where you are, your surroundings, how often, what's around you.   Sometimes they do need cleaning.  No one cleans to pass the time.....

[alan potts]

Nice set of pictures there, I have a wash cycle on my washing machine that works  delicates  .

Alan