Well....that was an unmitigated disaster. The emulsion melted down well enough in 35mm film cans, but it was like doing wax-resist painting. When I went to pour the emulsion on the plates, it was practically beading up and not sticking at all. Whether I poured directly from the film can or tried a syringe I could not get any adhesion. I washed the plates with calcium carbonate, a drop of dish soap, and scrubbed them with a cotton pad. I let them dry thoroughly and then subbed them according to these instructions:
Preparation of subbing layer (done under normal lighting). It is essential that an initial subbing layer be attached to the glass, or else the emulsion layer will simply detach during tray development. Although varnish may work too, the traditional gelatin subbing layer is the most
e$ective. In addition, it can be removed with bleach if one wishes to reuse the glass. The following recipe is what I use for a batch of four 4×5′′ plates, though far more plates could be treated with this amount:
A. Heat up 50ml. of distilled water to a maximum of 50 degrees C. (about 125 degrees F.) in a beaker. Then pour 1g. (1/4 teaspoon) of chrome alum into this water and stir with a standard darkroom paddle until dissolved. Without this hardening agent the subbing layer tends to frill and sometimes completely separate from the glass during tray development; so the small expense is worth it.
B. Sprinkle 3.5g. of gelatin onto surface of 236ml. (1 cup) of distilled water. Let this stand for 10-15 minutes so that the gelatin can swell up. Then heat up the mixture until the gelatin is dissolved. Pour contents into a third container that is speci#ed for photographic use only.
C. Add 5ml. (1 teaspoon) of chrome alum hardener solution (from step A) to gelatin solution to make a total of approximately 240ml.
D. Add approx. 15ml. (1 tablespoon) of Photo-Flo to this same mixture to make approx. 255ml. of gelatin/chrome alum/Photo-Flo solution.
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E. While the solution is still warm, pour it over the glass plate and spread evenly by tilting the glass. Because it isn’t always easy to see which surface has gelatin, I go ahead and pour gelatin over both surfaces. Once this is done, carefully lean the glass against a vertical surface to dry. In order to prevent excess gelatin from collecting at the lower end I drain o$ most of the excess and allow the surface to cool somewhat before placing it vertically. Allow the plates to dry for at least 6-8 hours before proceeding with the next phase.
The chrome alum solution (the 45ml. left over) will only keep for about a day, so it should be disposed of. Why the waste? Because I can’t measure a smaller amount accurately. I keep any left over gelatin/chrome alum/Photo-Flo solution in the refrigerator for a day or two in case I wish to make more plates. After three or more days this solution loses it’s beneficial properties and should be disposed of. (Source: The Dry Plate Process. Mark Scholer Peterson.
www.alternativephotography.com)
Where am I way off the mark? I can reuse the coated plates by cleaning with bleach, correct?
I stopped after 2 and had 4 more ready to go. I didn’t want to waste more emulsion.
I realize that there’s a learning curve to this and am willing to pay the tuition for the lesson.
I already have a new and better appreciation for how good the guys that had to do it this way were.
Thanks in advance.
