How do you prepare a glass plate for use as a neg

[waynecrider]

Total newbie here, and having not read too much on the subject, I was wondering just how glass plates are coated, or sensitized, for use in todays world. Can someone clue me in on the procedure and how adhering the emulsions are.

[JG Motamedi]

Wayne,

I think the only commercially available glass plates are from Russia made by Slavich.

http://www.retrophotographic.com/shop/41/

If you are wondering about a do it yourself version, you have a few choices, suspending silver salts in collodion, albumen, or gelatin.

Lots of details here:

http://albumen.stanford.edu/library/...nbeam/toc.html

Collodion, especially wet-plate collodion is having a great comeback in recent years, and you could probably find a weekend seminar near you to learn. Its not terribly difficult, but does take quite a bit of effort. Here is a brief summary from Wayne Pierce:

http://www.companyphotographer.com/h...tructions.html

Once you get collodion wet-plate under your belt, you can try collodion dry-plate. Same basic idea, but with a bit less speed and a few more steps.

I know there must be people out there making gelatin dry-plates, but I don't know any personally. Some details here:

http://www.apug.org/forums/article.php?a=44

Considering the much touted "death of film" (tongue firmly but cautiously in cheek), it would make sense for somebody to start working on a reliable gelatin dry-plate, any comments?

[TheFlyingCamera]

There is an excellent book out there that covers in some but not excruciating detail a wide range of "alternative" processes - Coming In To Focus, by John Barnier. He gives a good overview of wet-plate collodion.

Just a word of caution - the chemistry involved in wet-plate collodion is pretty nasty. Collodion (nitrocellulose... aka the movie film that goes BOOM!), ether (to dissolve the nitrocellulose so it will flow and adhere to the glass plate), hydrochloric acid, and cyanide. It can of course be done safely, but requires a modicum more advanced preparation and consistency of method.

The best thing to do as far as prepping glass plates is to order the glass pre-cut, and then polish the edges to smooth them so you won't be adding blood to the emulsion. The Barnier book gives an excellent summation. Having watched someone actually do wet-plate work, it is fascinating, and it is a relatively quick process (it has to be, because the plate has to be wet while being exposed).

[jnanian]

hi wayne

i've coated dry plates using store bought emulsion ( read: liquid light ) off-and-on since about 1986-7. there are other brands out there, some are variable contrast, and some are faster.

the main thing you have to worry about is creating a binding agent to for subbing your plates. i've tried a bunch of different ones from albumen to colodion ( bought at the pharmacy ) in addition to gelatin and urethane.
while the urethane works well, it yellows over time. the best i have used is knox gelatin. i know it isn't photo grade like the formulary or b&s sells, but it seems to have worked.

you need to clean off the glass before subbing -
wash well with a brush and washing soda and flow stop bath or vinegar over it so it "sheets off". you let the plates dry and you can either "flow"
the gelatin or brush it on. a few coats with drying inbetween.
some folks add alum hardener into the gelatin, i hear it works well, but have never done that myself ...

there are a few different ways to coat the plates. i have used those cheep foam brushes, and i have just poured the emulsion over the plate. you can put a few coats of the emulsion on as well. i haven't coated in a while, but when i did, i would have a hair dryer to dry the emulsion faster than "air drying". some say aged emulsion offers more contrast, other say you can increase speed by adding a little developer ( like dektol or whatever you use ) to the emulsion. the asa of liquid light is somewhere between asa 1 and 5, depending on the light conditions, age of the emulsion and wheter or not you incorporated developer. after you make your exposure you process like paper under a red light. a few things to worry about: if your binder didn't hold down your emulsion completely, it will lift off the plate, stretch and crease, or it will lift off, and you will lose your image down the drain - kind of like a polaroid emulsion transfer

there is a bunch information here ( probably explained better than i did ): http://www.alternativephotography.co..._dryplate.html

and the book "liquid silver emulsion" is pretty much the bible on this sort of thing: http://www.alternativephotography.co...r_gelatin.html

good luck!
john

[JG Motamedi]

John,

Thanks for the interesting post. Have you tried to make your own gelatin emulsion with that Kodak recipe or know of anyone who makes their own? I have been itching to try dryplate for a while now. Wet-plate is great but I can't move more than a few meters from the darkroom. How many plates can you get out of a bottle of light?

jason

ps: I think the "dangers" of collodion are overstated. Cutting glass is very easy as long as you spend the $20 on a good oil-type cutter (Toyo makes a great one). Also, the set-up isn't likely to blow up, since collodion is only dangerous at one stage of its production, and very few people make their own collodion; it is commercially available. Lastly, there is no reason to use potassium cyanide as a fixer, regular hypo works just fine.

[shinn]

"silver Gelatin" written by martin reed and sarah jones goes into great detail about making silver gelatin emulsions with a lengthy section on glass, and a good section on troubleshooting...which is needed....cause I didn't find this easy to do.

The book of alt processes by christopher james also gets into working on glass as well.

Making it from scratch is a bit of a PITA...for me the most difficult part was temperature control which decides speed and contrast, but I now have a hot plate/stirrer which should make things a lot easier next time. I hope.

Happy Days
Mark

[Claire Senft]

The product may have been discontinued but Kodak was making Tmax 100 glass plates and I think Technical Pan also.

[JG Motamedi]

The product may have been discontinued but Kodak was making Tmax 100 glass plates and I think Technical Pan also.

All Kodak glass plates were discontinued about four years ago. I think they were used primarily for astronomy and electron microscopy, and were incredibly expensive.

I do recall seeing some Agfa glass plates for sale somewhere.

[David A. Goldfarb]

The Slavich plates can readily be found at holography suppliers. There's a panchromatic emulsion, an ortho emulsion, and some specialized emulsions more for holography and scientific use.

[Ole]

All Kodak glass plates were discontinued about four years ago. I think they were used primarily for astronomy and electron microscopy, and were incredibly expensive.

That should be about right, I just got two boxes of 13x18cm plates off German ebay. But they weren't that expensive - now. About 2 Euro apiece - 50 Euros for two boxes of 12.