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Distilled water


A Planck
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Hi, I'm cleaning my dob primary again but I can't seem to get hold of and distilled water. Everyone offers me 'deionised' but that isn't the same. If anyone has any ideas, I'd be very grateful to hear them. Alex

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Note quite the same as it removes ions only, but it can leave other remnants in there, such as bacteria and other uncharged molecules. To be on the side of caution better use distilled. I don't know abut mirror cleaning personally from experience, but all the same distilled is what I would go for.

I would also be cautious about attempting making distilled water at home, unless you know what you are doing and have the equipment, it will not be of the highest purity otherwise( more than likely ) though it may not be that critical and pure enough.

Edited by AlexB67
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I used to use distilled and now i just use tap water and havent noticed any difference at all.i live in quite a soft water area so maybe that has some bearing but i dont waste money anymore on distilled

Thing is when normal water dries it can leave debris behind and cause stains, so it is not ideal, soft or not it will have other chemicals in it, boiled or not, you could end up scratching optical surfaces I imagine. Just because it may not be visible in an obvious way, repeated application of standard water I would think is not ideal when you let it dry out, that would be my guess anyway. I would think a final good rinse with distilled would not be a bad idea before letting it dry. No doubt the expert cleaners will comment on that. I'd be interested to hear because my secondary could do with a wash at some point I think :)

Edited by AlexB67
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By the way, I use the distilled water to rinse the mirror after I have cleaned it with tap water and fairy liquid. The water down here is very hard so if you don't rinse it properly, you end up with water marks. The mirror come up like new if you do. Alex

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I don't have any problems using deionised water. The water runs off during the final rinse and any droplets can be wicked up with the corner of a kitchen towel.

You will get far more air-born bacteria and micro-dust settling in use than from anything in the de-ionised water.

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as i said,i havent noticed any difference and i clean my mirror's every 3 months but i dont let the final rinse of water dry on the mirror i use a large blower to get rid of it.if it leaves a residue its not detectable to the eyes therefore it doesnt detract from visual observations :)

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De-ionised will do perfectly, the only stuff that remains in deionosed is organic (non charged) material which is at such a low level it's essentially not there!

If you buy some water you can test it simply by letting a few drops evaporate and see if it leaves a residue, best to cover with something though as the drop can collect dust from the air if the environment isn't dust free.

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So I guess deionised is okay and pure enough is the conclusion ?, useful to know :) If I can get distilled I buy it but if not I'll go with the deionised, tap water I'd be hesitant though.

@Crashtestdummy. I am not sure I'd feel comfortable with that view, what the eye doesn't see just by looking it. I mean a mirrors must be a very finely polished surface, so any residue you may not see by eye doesn't mean it doesn't leave anything behind at a molecular level, and it may therefore affect the coating over time, that would seem logical to me, depending how tough the mirror finish is and it can withstand it for some time I guess ? In any case I read a few articles now and yet to see one that promotes that practice as a good one.

Edited by AlexB67
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I used to use distilled and now i just use tap water and havent noticed any difference at all.i live in quite a soft water area so maybe that has some bearing but i dont waste money anymore on distilled

My thoughts, precisely. Having read recently about people cleaning the mirror of a 25 inch dob with tap water and a pair of underpants (unworn) and never having used anything except ordinary water myself I've never seen any degradation or residue left from the cleaning process.

Let's face it; the very first night your distilled-water-cleaned mirror gets dew on it (a very dirty form of water: lots of dust, pollen, bacteria, acid rain and other nasties) any benefit from using purified water will be completely negated.

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Ice build-up in the freezer is "distilled water" when melted. Just make sure it hasn't got spilled food in it. It would be a great pity to claim a new comet and have the embarrassment to have to admit it was part of a left-over pizza.

P

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My thoughts, precisely. Having read recently about people cleaning the mirror of a 25 inch dob with tap water and a pair of underpants (unworn) and never having used anything except ordinary water myself I've never seen any degradation or residue left from the cleaning process.

Let's face it; the very first night your distilled-water-cleaned mirror gets dew on it (a very dirty form of water: lots of dust, pollen, bacteria, acid rain and other nasties) any benefit from using purified water will be completely negated.

True, not really considered that, silly me and acid rain for that matter in some areas, perhaps I'd be using just a tap after all :D

I found this article quite handy which does seem to mention using distilled/deionised for rinsing though. I can see why once you start wiping it if you need to why deionised is useful. When a mirror is under the elements you can't touch it, or at least it is in the cell not to be touched, so you can't scratch it, but with a wipe you can.

http://www.skyandtelescope.com/howto/diy/3437191.html?page=3&c=y

Interesting thread, so many opinions on these things that vary a lot, as seems to be the case in this hobby :D

Edited by AlexB67
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I think tap water might only be a problem if you actually let droplets of water dry on the mirror surface.

If you tip them off and leave the surface dry, then no residue.

In a hard water area you will definitely get limescale spots if any drops dry on the mirror.

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Have you considered making your own distilled water?

Boil some water in a saucepan with an piece of glass suspended above it for the steam to condense on, and have the glass at an angle so the water trickles down it into some suitable receptacle for collection.

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