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I wouldn't wash any mirror with a coating less than a year old. I made the mistake with my first scope and scratched the mirror (though the scratch was very fine and did nothing to the view).

A couple of weeks ago I washed the primary and secondary of my 12" flextube - it was about 5 years since last time so I figured they could do with it. I cleaned them the same way I wash my specs every day: under the kitchen tap with washing up liquid, using my finger to rub clean.

(Pauses for gasps of horror...)

With a cotton wool ball you can probably feel grit down to about a tenth of a millimetre. With a fingertip you can feel hundreths or even thousandths. When I scratched my first mirror years ago it was with cotton wool. Using my fingertip I was left with an immaculate, scratch-free mirror. Some water spots didn't drain off: I used a hair dryer on them, which left a few visible spots when the mirror was held at the right (or rather wrong) angle under strong light. They make absolutely no difference to the views. I'll do the same thing again in another five years.

I saw the fingertip approach on a youtube vid a while back and after the initial shock I realised it was the obvious way to do it - I can certainly vouch for it. In the past I've used isopropyl alcohol - and made myself giddy with the fumes. I'll stick to washing up liquid thanks.

And by the way, don't forget that all the light from the primary comes to the eye by way of the secondary and eyepiece: the system is only as good as its dirtiest part. That's why I gave my secondary the same treatment. Eyepieces, needless to say, don't get dunked under the kitchen tap...

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I would be very careful in buying ANY iso-propyl alcohol - that isn't certified as chemically-pure from either a chemical-supply outfit - for laboratory-use - that's listed as "Reagent Grade." Or a ph

David Lukehurst says not to clean for the first six months as you need to let the coatings harden. http://www.dobsonians.co.uk/Mirror Care.html

I wouldn't wash any mirror with a coating less than a year old. I made the mistake with my first scope and scratched the mirror (though the scratch was very fine and did nothing to the view). A c

14 minutes ago, faulksy said:

thank you all. di-ionised it is

MIKE!!!! You don't seem to be listening to the general consensus that it's a BAD idea to wash the mirror. think long and hard before you do anything. I don't want the views to be degraded before I get a chance to see them in November :D

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8 minutes ago, Scott said:

MIKE!!!! You don't seem to be listening to the general consensus that it's a BAD idea to wash the mirror. think long and hard before you do anything. I don't want the views to be degraded before I get a chance to see them in November :D

its only to rinse it scott, its got chilli all over it after calv was drooling :icon_biggrin:

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23 minutes ago, Scott said:

MIKE!!!! You don't seem to be listening to the general consensus that it's a BAD idea to wash the mirror. think long and hard before you do anything. I don't want the views to be degraded before I get a chance to see them in November :D

It's not bad but the Nichols where it's at!

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1 minute ago, estwing said:

It's not bad but the Nichols where it's at!

Don't worry mate, I'll give yours a good workout too, providing the lights from my imaging rig don't blind you ;)

 

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5 minutes ago, Scott said:

Don't worry mate, I'll give yours a good workout too, providing the lights from my imaging rig don't blind you ;)

 

that won't be polar aligned for long then :icon_biggrin:

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