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Cleaning a Secondary

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#1 cloud_cover

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Posted 22 January 2013 - 11:42 PM

I know this must have been asked many, many times but I thought I'd get specific advice for my scope. Thanks for "bearing" with me.
The scope is a rather old Tscopes (2004) and the secondary looks like it has spider-like patterns of dirt on it. I'm thinking of getting it cleaned. So far I only have experience with refractor and eyepiece cleaning where I use a bulb blower followed by gentle dabbing with a soaked cotton ball impregnated with methylated spirit, then gentle wiping off with dry cotton ball. For refractors, eyepieces, and my Televue Everbrite dielectric diagonal mirror, so far so good.
Will this be OK as well for a secondary mirror or must different techniques be used?

#2 Jon Isaacs

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Posted 22 January 2013 - 11:57 PM

Will this be OK as well for a secondary mirror or must different techniques be used?



A different technique must be used because mirror coatings are much softer than dielectric coatings or lens coatings.

Basics:

First blow the dust off with a bulb or canned air (careful)

Rinse under clean running water.

Soak in clean water with a tad bit of soap.

Rinse with distilled water and allow to dry...

If the mirror still needs cleaning, then repeat, soaking mirror and then "float" a wad of cotton balls across the mirror surface to ever so gently clean the surface with zero pressure.

Rinse with distilled water, allow to dry, possibly dabbing remaining drops with soft tissue.

That's how I do it. Others may have better systems. Don't use a brush, I learned that one the hard way.

Jon

#3 cloud_cover

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Posted 23 January 2013 - 12:09 AM

Thanks Jon! You're always dependable on for good advice :)
By the way, I'm having the very pleasurable experience of assembling my (new-to-me) first ever Dob!
Its quite an adventure and I only wish it would go faster but I don't want to wreck anything! Especially since its at least 10 years old.

#4 panhard

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Posted 23 January 2013 - 12:12 AM

That is why Jon is a star contributor. :bow:

#5 paul hart

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Posted 24 January 2013 - 08:26 PM

Good advice from Jon. I just wanted to say hi to a fellow TScopes owner. There aren't very many of us. It's a good scope
I've had it for 7 years.

#6 cloud_cover

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Posted 24 January 2013 - 08:40 PM

Hi Paul :)
Yeah, I've heard only good things about its operation. Pity that its no longer in production though.
The movements feel awfully smooth and nice even though the UTA and mirror haven't been assembled yet.
I'm really looking forward to first lighting it, probably next week. Amazingly, the weather's been co-operative, but maybe that's because the scope hasn't been assembled yet!
Nice "meeting" you :)

#7 KerryR

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Posted 25 January 2013 - 10:00 AM

Don't use a brush, I learned that one the hard way.

Jon


Me too, after a dusty day at the Texas Star Party. Embarrassing.

#8 cloud_cover

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Posted 10 March 2013 - 07:55 PM

Just to update you guys:
I removed the secondary, held it in my hand and simply flooded it under the kitchen tap. This removed most of the large objects but not the fine dust (Yes, I know you should leave well alone but since I am cleaning the thing...) so I used surgical cotton (the kind used to clean babies' unbilical cord), completely wet under the running stream of water to brush off the surface while holding the mirror in the vertical.
Seems to work. Discovered 3 small sleeks but they are in a perpendicular direction to my cleaning strokes so I think they must have been there previously.

#9 Tony~M

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Posted 10 March 2013 - 10:06 PM

Hello,

Make sure you rinse it off with distilled water after you wash it with the tap water. Tap water has lots of impurities that will deposit on the mirror, not to mention the chlorine content.

Personally I skip the tap water step and just use jugs of distilled water.

Just fill a rubber tub with distilled water and some gentle hand dish soap (I use Joy), take your surgical quality cotton balls and swirl the water above the surface of the mirror to get off stubborn dirt.

After it is clean pour clean distilled water over it to rinse and put it vertical on a towel to dry.

As the water drips off you can use your cotton to touch the water drops that remain to suck them off of the mirror.

Later,

Tony

#10 Víctor Martínez

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Posted 11 March 2013 - 04:29 AM

Use pure acetone. A few days ago I cleaned mine with this method and it has been flawless.
http://www.spectrum-...rints Video ...






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