View Full Version : Cleaning Ground Glass

John C Murphy
30-Mar-2005, 13:23
Some sea water got in between the plates of my Toyo monorail's ground glass. I took it apart and tried to wipe it off, but there is still a mark. There a two plates, one is the ground glass, the other seems to be some sort of plastic material with concentric circles etched in it. So what is the technique for cleaning these parts?

Gem Singer
30-Mar-2005, 13:52
Hi John,

That plastic piece with the concentric circles is the Fresnel lens. When re-assembling, be sure to put the pieces back together the exact same way they were arranged when they were dis-assembled, with the proper surfaces facing their original direction. Toyo places their Fresnels under the ground glass(between the ground glass and the lens). Their mounts make an allowance for the focus shift from the Fresnel.

Treat the ground glass, Fresnel, and cover glass the same way as you would treat a sheet of film. Swish them in a tray of distilled water to which a few drops of wetting agent has been added. Place them on edge on a clean, dry towel to drain and dry. The grid lines on Toyo cover glasses are acid etched, so not to worry about wiping them off. However, there is no need to wipe if handled carefully.

John Hoenstine
30-Mar-2005, 17:13
Hi John,
Salt water is a big problem. I might put everything in a tray with a Kodak syphon and let it run for a while. Also check all every other part of your camera. I have had a camera ruined by fresh water so just make sure everything is OK.
Good luck, John

ronald moravec
30-Mar-2005, 17:33
I have tried to clean ground glass amd even distilled water left drying marks. I ended up using canned air for a quicj dry.

Don`t scrub on the frenel as it is most likely plastic an will scratch. No solvents either.

Thilo Schmid
31-Mar-2005, 06:27

the best way to clean a fresnell lens (as well as many other things) is using an ultrasonic cleaner. However, the consumer models (e.g. for contact lenses) are usually too small. Laboratories do have bigger ones to clean all kinds of test tubes. You may also find a cheap used one on ebay. A model that fits half of your fresnell / ground glass is big enough, because you can clean both halfs in two runs.

Calamity Jane
31-Mar-2005, 06:33
For the cameras I have built and for the GG I have made, I scrub under hot running water with dish soap and a plastic bristled bruush (like an old toothbrush) then rinse thoroughly under hot running water. Shake the excess moisture off and, if you have got the plate good and warm (which it should be by now) the excess mositure will evaporate REAL quick - handle only by the edges at this point.

I think you will nead soap, lots of hot water, and scrubbing to get the salt residue off the glass.

I don't know if your plastic fresnell would tollerate scrubbing.

Scott Rosenberg
31-Mar-2005, 13:44
hey john... to clean the frensel, pour some distilled water in a Tupperware container, the place the fresnel in it and swish it around a bit. pour off the water and replenish with fresh stock. then taking care to only touch the fresnel by the edges, lift it from the distilled water bath and spray it with lens cleaner. using a very soft bristled brush, like a lens cleaning brush, GENTLY rub the surface, moving in circular pattern approximating the pattern of the fresnel lines. do this for both sides, though for the smooth side of the fresnel you can brush in whichever direction you please. then drop the frensel back into the distilled water bath and swish around some more. lastly, remove the fresnel from the water, only holding it by the edges, and dry it with a hair dryer - this is the only way i have EVER been able to clean one of these things without leaving marks. pass the fresnel back and forth in front of the hair dryer, moving it constantly through the air stream so that the plastic doesn't heat up. if your hair dryer has a cool setting, all the better.
i have done this successfully on one ebony, one rollei, and two linhof screens without any ill-effects.

good luck!