Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> ATM, Optics and DIY Forum

Pages: 1
JohnH
Carpal Tunnel
****

Reged: 10/04/05

Loc: Squamish BC Moved!!!!!
Cleaning rough off Mirror being Made
      #6135100 - 10/13/13 02:04 PM Attachment (10 downloads)

I am getting back to my 12.5 f4.8 project and I wanted to improve the look of my mirror before doing final tests and corrections.

There is still some rough present from the polishing process and I wanted to clean it off before sending it for coating.

Tried using turpentine, paint thinner and methyl hydrate, as I thought part of the reason it stuck on so well is some pitch is mixed in with it. None of these worked and I wanted to clean it to leave the molded sides and ground bevel intact.


Post Extras: Print Post   Remind Me!   Notify Moderator  
prfesser
member


Reged: 09/09/13

Loc: Kentucky
Re: Cleaning rough off Mirror being Made new [Re: JohnH]
      #6135133 - 10/13/13 02:22 PM

I recall a suggestion in one of the telescope-making books in which the author used a pencil eraser to remove rouge. If using this method I'd be very careful not to let the eraser slip onto the optical surface.

Best -- Prfesser


Post Extras: Print Post   Remind Me!   Notify Moderator  
JohnH
Carpal Tunnel
****

Reged: 10/04/05

Loc: Squamish BC Moved!!!!!
Re: Cleaning rough off Mirror being Made new [Re: prfesser]
      #6135163 - 10/13/13 02:44 PM

Didn't touch it, even in the spots where there wasn't that much.

I am considering doing a silver coating as a tst on a small mirror, so I will have nitric acid around sooner or later.


Post Extras: Print Post   Remind Me!   Notify Moderator  
planet earth
Pooh-Bah
****

Reged: 09/07/10

Loc: Ontario Canada
Re: Cleaning rough off Mirror being Made new [Re: JohnH]
      #6135231 - 10/13/13 03:19 PM

You could try warm the mirror blank up in water slowly and then use turps.
Maybe 90-110 deg F or so, to soften up the rouge /pitch.
Sam


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Cleaning rough off Mirror being Made new [Re: planet earth]
      #6135380 - 10/13/13 04:47 PM

Acetone nicely dissolves pitch, and leaves no residue. Use it in a well ventilated area. It may not be effective on dried-on polishing compound, for which scrubbing with a nylon brush and a cleaner such as Spray Nine might be more efficacious.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Jeff Phinney
super member


Reged: 02/20/13

Loc: CA
Re: Cleaning rough off Mirror being Made new [Re: GlennLeDrew]
      #6135716 - 10/13/13 07:48 PM

I'm assuming that the stain is not going to be visible once the mirror is mounted in the telescope.

Question: If the stain is on the side or back of the mirror and not on the face, why worry about?


Post Extras: Print Post   Remind Me!   Notify Moderator  
GlennLeDrew
Postmaster
*****

Reged: 06/18/08

Loc: Ottawa, Ontario, Canada
Re: Cleaning rough off Mirror being Made new [Re: Jeff Phinney]
      #6136265 - 10/14/13 03:31 AM

Stains should pose no problem. But I wonder about outgassing from pitch in the vacuum chamber during coating; it's safest to eliminate that.

Post Extras: Print Post   Remind Me!   Notify Moderator  
David Castillo
Carpal Tunnel
*****

Reged: 09/09/06

Loc: Carmel Valley, Ca
Re: Cleaning rough off Mirror being Made new [Re: GlennLeDrew]
      #6136895 - 10/14/13 12:45 PM

You might get it off with toluene. It's an organic solvent that should dissolve that residue. It is also capable of dissolving a number of notable inorganic chemicals such as sulfur, phosphorus, bromine, and other non-polar covalent substances, so it could do the trick.If you use it be careful, it's vapor is neurotoxic if too much is inhaled. I've used it on tissue samples on slides to dissolve wax.
------
Dave


Post Extras: Print Post   Remind Me!   Notify Moderator  
Don H
sage


Reged: 12/28/06

Loc: Midwest US
Re: Cleaning rough off Mirror being Made new [Re: JohnH]
      #6137028 - 10/14/13 01:32 PM Attachment (3 downloads)

Hi John. In the past I have used detergent and a soft scrub brush to clean my mirrors of rouge residue, often followed with alcohol and more soapy water. Ultimately your coater will clean your mirror to the point where I think you won't have to worry. A little left over rouge color is testament to your mirror making endeavour.

Regards,
Don


Post Extras: Print Post   Remind Me!   Notify Moderator  
ccaissie
professor emeritus


Reged: 09/13/10

Loc: Whitefield, Maine
Re: Cleaning rough off Mirror being Made new [Re: GlennLeDrew]
      #6148568 - 10/20/13 03:10 PM

Quote:

Stains should pose no problem. But I wonder about outgassing from pitch in the vacuum chamber during coating; it's safest to eliminate that.




I was assured from a coater I used to use that epoxy on the back to secure a nut in a conical blank would not cause outgassing...that it was an overblown concern.

Now after a year, they still can't deliver a decent coating, so maybe he doesn't know what he's talking about. I'd say clean it up the way they used to tell you, just to be sure.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Mark Harry
Vendor
*****

Reged: 09/05/05

Loc: Northeast USA
Re: Cleaning rough off Mirror being Made new [Re: ccaissie]
      #6149412 - 10/21/13 08:36 AM

I got a way.
It's called SCOTCHBRIGHT. In getting the glass polished out, I go to the sink and it cleans up the edge nicely. (just the EDGE!)
Then, I figure the mirror with a few short spells, and as soon as I lift the polisher off the glass, I spray the heck out of it with a spraybottle. This dilutes the alkaline characteristic the swarf might have, and prevents re-deposition of the crusty stuff. Then it's a total sink rinse to leave a nice pristeen optic. Works for me.
If your water is notably hard, do the rinses and sprays with distilled H2O after scrubbing the edge off.
M.


Post Extras: Print Post   Remind Me!   Notify Moderator  
JohnH
Carpal Tunnel
****

Reged: 10/04/05

Loc: Squamish BC Moved!!!!!
Re: Cleaning rough off Mirror being Made new [Re: Mark Harry]
      #6150808 - 10/21/13 11:01 PM

I had forgotten that the act of grinding and polishing Pyrex results in a chemically changed material that can (and does) stain crown and flint lens blanks being worked if not rinsed promptly.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
8 registered and 24 anonymous users are browsing this forum.

Moderator:  ausastronomer, richard7, Starman81 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 465

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics