How to make a positive dry plate? (liquid emulsion)
Last month I start being obsessed in making calotypes. It's been a while I became obsessed in taking photographs and making prints in the most old, traditional and often weird way possible.
At the same time I didn't stopped printing my bw prints and occasionally some bromoil. I use only liquid emulsion (generally on paper) and it's very rare for me to print on modern factory-made papers. Anyway, I was running out of emulsion... So I decided to prepare some bromide emulsion myself. I did it once in Denmark with Emil Schildt and worked well. I did it again now and worked still perfectly. I just followed instructions for the only unwashed bromide emulsion described in the "Silver Gelatin" book (the bible of liquid photographic emulsions). This time I attempted to prepare also some "gaslight" silver chloride paper too, but results were odd. I did not investigate on that because I'm happy with the bromide emulsion. Key factors are gelatin type/quality and temperatures. The homemade bromide emulsion is great for regular b+w printing, b+w toning, and even bromoil.
Yesterday I had this idea of trying to make a dry-plate... I made wooden plate holder for a 4x5" camera and I couldn't wait too long to try it with a "real" plate. With great surprise it worked very good on ordinary glass. No noticeable frilling on the edges, just a couple of bubbles. And no subbing layer! All kinds of commercial emulsions always lifted from the plate when placed in the developing bath. The exposed and developed plate is now drying and looks soooo nice. It's a bit slow though. Under the enlarger the emulsion took 5 minutes at F4 to deliver a good, contrasty picture. Used as dry plate, with 7' at F8 I had a badly underexposed image (indoor lighting, it was evening time). Anyway I've rated the emulsion ISO 3-5 (like my latest calotypes), which is ok enough to photograph people during daytime.
It would be really nice to make positive plates. I know that collodion wet plates consist essentially of an underexposed/underdeveloped negative that looks like a positive when placed over a dark/black surface. While daguerrotypes were real positives, right? And how would it work for a dry plate made out from a silver bromide gelatin? Is there any process for inverting a bw print that will work in my case?
Last edited by Fulvio; 11-29-2006 at 06:29 PM. Click to view previous post history.