The DARKROOM COOKBOOK, Third Edition

Printing Out Processes 155
Add the strontium chloride to distilled water and dissolve by gentle heat and agitation
using a glass rod. Add to this the alcohol and glycerin and mix well.
Solution B
Collodion USP, 250.0 ml
Alcohol, 85.0 ml
Add the alcohol to the collodion and mix until dissolved. Add chloride Solution A to the
collodion Solution B and mix well. This is now called “Salted Collodion.”
Solution C
Citric acid, 1.8 g
Alcohol, 2.0 ml
Add the citric acid to the alcohol and mix until dissolved. Add this to the Salted Collodion
Solution.
Solution D
Silver Nitrate, 6.0 g
Distilled water, 7.0 ml
Alcohol, 20.0 ml
Add the silver nitrate to some of the distilled water and dissolve. The less water you
use to dissolve the silver the better. Add the alcohol to the silver solution and mix until
dissolved. You will now have two distinct solutions; the Salted Collodion and the silver
nitrate. The emulsion is made by carefully combining these two solutions.
Making the Emulsion
A mechanical magnetic stirrer is great for emulsion making. In lieu of that, you may stir
the solution with a glass rod in one hand while adding the silver solution with the other.
The following should be performed under safelight conditions, using either amber or red
light. Making the emulsion involves adding silver nitrate solution to the halide solution
with constant agitation. The silver may be added by using a plastic hypodermic syringe
with a fi ne opening. In collodion emulsions the silver may be added in a thin continuous
spray while the collodion solution is being stirred. As the silver is added, the collodion
will change from a clear liquid to an opalescent color.
Once the silver is added, pour the emulsion into a very dark brown glass bottle, or
better yet search your local antique shop for the less common black glass bottle. Cork
the bottle and shake it vigorously for a couple of minutes. Set the bottle aside, undisturbed
for at least a day. Never allow the emulsion to be shaken again, as this will stir
up any precipitates and produce millions of fi ne bubbles, both of which will make it
impossible to make an even coating. The mixed emulsion has a remarkable shelf life if
kept in a cool, dark place.
Coating Paper with Collodio-Chloride Emulsion
Because collodio-chloride emulsions are alcohol/ether based, paper for coating must
be either heavily sized with hardened gelatin or coated with a baryta layer. The baryta