Coating 2.5X3.5 glass plates for Certotrop

[grain]

Recently got a really neat Certo Certotrop, Xenar 120mm. Has a 120

back. Would like to play with coating my own plates, have some

holders. Has anyone any experience doing this? Luminos/liquid light

is what I plan to use. What pointers? ASA? How thin to lay it on etc.

Thanks all.

[don_mckeith]

I don't want to discourage you from coating your own glass plates,because I learned alot from coating mine-which I was never 100% successful at-

 

but-liquid light is a paper formula,which is very useful for coating all kinds of surfaces for PRINTING on,but for in camera negs-IMO RC paper works just as well(or better(more consistant)than LL.

 

here's a link on pre flashing RC paper for in camera negs,which I have used,and can attest to-is much less of a hassle,with -equal to or better than results.

 

http://spitbite.org/pinhole-discussion/2004/0411/0800.html

[neil_parker]

Remember that Liquid Light and photo papers are orthochromatic and not sensitive to red

light, so only useful for special effects. Kodak used to make a panchromatic B/W paper

called Panalure, for making prints from color film, not sure if that is still made however.

Your best bet might be cutting down sheet film.

[silent1]

Why cut sheet film? 6.5x9 cm film is readily available, albeit in a very limited choice of emulsions (maybe only one, most of the time).

 

But coating glass plates is semi-practical. Most plates from before WWI would have been orthochromatic or even blue-sensitive anyway (1910-ish advertising touts orthochromatic films, suggesting they were still newish, at least as consumer items). Further, pre-WWI plates were also pretty slow; a modern ISO 25 equivalent would have been "normal" and ISO 50 "fast". With liquid printing emulsion, you can expect a speed roughly between ISO 1 and 6, or about two stops slower than a "normal" plate from 1910. There may be some oddities with the multi-contrast emulsion, in that scene color will affect contrast unevenly across the plate, but that's never stopped thousands of pinhole photographers using printing paper for their camera negatives (and doing it at f/128 to f/350 or slower).

 

There is information around on making your own gelatin emulsions, including speed control, panchromatizing, and how to keep the gelatin on the glass. It's scattered, and it'll be a big project to get it all together, but there *are* people doing this, and getting quite nice results. You could even go to collodion wet or dry plates -- information on this process seems easier to find than gelatin plate making, perhaps because it's never completely vanished from the photographer-made arena the way gelatin dry plates did for most of a century...

 

Or you could take the "coward's" way out and buy Russian made plates (they were $8 per plate in boxes of 12 a year or so ago, 9x12 cm format) and cut them down to your format (in total darkness -- watch out for glass splinters, ideally use an IR night vision setup). You'll get two slightly narrow plates from each 9x12, and probably won't find it difficult to adapt your holders to these 6x9 cm plates.

[jorn ake]

You might try Christopher James' book, The Book of Alternative Photographic Processes. I seem to remember that he covers tintypes, but I am not sure if I remember that he does glass plates. My books are in a room full of sleeping (oh thank god) nieces who are visiting right now. He does have a pretty good list of sources in the back. One of them is Photographer's Formulary who carry quite a range of chemistry. The other is Chicago Albumen Works, makers of POP or printing out paper for those glass plate negatives after you are done.

[don_mckeith]

btw- there is a rather lengthy discussion about making glass plate emulsions over at the "alt process "board -about halfway down the page-" Kodak tech pub AJ-12". If you call Jane Fisher @ kodak doc.'s and pattents in Rochester she'll send you a copy(I don't have the phone # offhand but customer serv. will give it to you.

[grain]

I'm not daunted. The Certo I'm using is un-coated, so ortho is what it probably prefers. Hadn't thought about the VC/color in the scene-issue before, but that could be the fly in my ointment.

Paper negs I have done with this and work fine, but I'm a romantic, and want to do some plates. Tintypes or Ferrotypes I hadn't thought of either, but also a great idea, and may be easier than the glass. Have the old Encylopedia to follow for that process.

 

Thanks a lot, A.