Best Way to clean Ground glass.

[gary892]

Greetings,
I have a Chamonix 45n-2 camera and I noticed the ground glass is dirty and has a slight fog to it.

When I started to remove the ground glass I noticed there are 3 sheets of glass.
1. This is the piece of glass that has the grid on it and it labled Chamonix and closest to the lens.
2. This piece is the Fresnel lens and it sits on top of the 1st piece, the one with the grid lines.
3. This piece looks to be a plain sheet of glass with no special properties that I can determine and it is the piece that my loupe rests against to focus.

So my question is: are the sheets of glass in the correct order and what is the recommended way to clean the sheets of glass.
What should I use as a cleaner and type of cloth to use.

I would guess that Windex and paper towels are out of the question.
I do have a can of all purpose window cleaner.

As usual your advice is always appreciated.

Thanks

Gary

[Tin Can]

Dawn

[nolindan]

Windex is entirely appropriate. Windex won't attack glass or plastic. Lots of rubbing and scrubbing will scratch things up - so a cleaner that really works and minimizes cleaning abrasion is the safest.

Washing the glass with dish soap and hot water, as Mr. Can has suggested, will also work well.

I imagine the Fresnel will not need any cleaning as it was protected by the ground glass and the protective glass and won't need cleaning. Cleaning will probably just get any dirt into the grooves of the Fresnel. Also, the plastic the Fresnel is made from scratches much more easily than glass.

I have been using Windex on coated camera lenses for 60 years and have never had any damage to the lens or the coating.

[maltfalc]

Windex is entirely appropriate. Windex won't attack glass or plastic.

windex or any other ammonia-based cleaner absolutely will attack plastic like acrylic fresnels.

[maltfalc]

if the grid is printed onto the glass rather than etched, it may wash off while cleaning it.

[Greg]

windex or any other ammonia-based cleaner absolutely will attack plastic like acrylic fresnels.

Agree 100%, based on a little bit of experience years ago. I use a diluted Plexiglass cleaner and final rinse with distilled (probably an overkill) water.

[maltfalc]

Agree 100%, based on a little bit of experience years ago. I use a diluted Plexiglass cleaner and final rinse with distilled (probably an overkill) water.

got this one perfectly spotless using tap water, a few drops of cheap dish detergent and a thrift store ultrasonic cleaner, then folding a paper towel around it and patting it dry.

[tgtaylor]

After blowing off the big particles with a ear syringe, I cleaned the corrector plate on my 10" telescope with 91% Isopropyl alcohol and a ton of Kimwipes making very light pressure circular passes around the circumference with the well soaked and folded Kimwipes. The brownish looking haze or film that had deposited on the corrector completely cleared and the plate now looks like new. I don't know if Isopropyl
would be appropriate for ground glass.

[Doremus Scudder]

Gary,

You have, in order from your eye to the lens, a protective glass cover, a Fresnel screen made of acrylic, and a frosted glass with grid marks.

The cover glass is fragile, but just glass. Clean it with Windex or dish detergent and water.

The Fresnel is very fragile and easily scratched. Dish detergent will not hurt it, but be careful handling it. Make extra sure you note the orientation of the smooth vs rough (circular-grooved) side of the Fresnel screen so you re-install it correctly!

The piece of glass closest to the lens, with the grid lines is the ground glass and has a frosted and a smooth side. The frosted side goes toward the lens. Be sure to install it correctly as well. If (but you need to check!) the grid lines are not water-soluble, you can clean the ground glass with dish detergent and water or Windex. Do do a test on the grid lines to see if they are water-soluble first! If so, then just brush that surface clean and clean the other side with a cloth dampened in Windex or distilled water. The test is important. I've washed of grid lines inadvertently before.

Best,

Doremus

[Mark J]

So my question is: are the sheets of glass in the correct order

Yes.