(there was a url link here which no longer exists)
have fun!
john
Wirelessly posted (BlackBerry9000/4.6.0.167 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/102 UP.Link/6.3.0.0.0)
Bumping and waiting for Denise.
What size plate are you interested in?
"Hypo" is sodium thiosulfate. Hypo is not Permawash. Permawash is a washing aid. Hypo is also not Hypo Clearing Agent, another washing aid, which you seem to have it confused with.
The sodium thiosulfate is a source of sulfur which is used to increase the film speed of the emulsion.
Thanks, I always get Hypo and Hypo clear mixed up...
Thanks for posting this PE.
EA;
Here is Mark Osterman's ISO 3 - 12 plate emulsion, courtesy of Mark, for your enjoyment. It has been posted here before, but I had to look it up so here it is.
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This formula will give an ISO 3 12 formula suitable for coating on plates. It is used by GEH (George Eastman House) for teaching purposes. It is a very early SR formula. I would like to thank Mark for permission to include it here.
You will need:
Silver Nitrate
Potassium Bromide
Potassium Iodide
Photograde Gelatin
Chrome Alum
Everclear (95% Ethyl Alcohol - NOT DENATURED)
Thymol
Solution A:
Add 2.6 grams of gelatin to 84 ml of water and allow to swell, and then heat until melted. Add 10.3 grams of Potassium Bromide and 0.6 grams of Potassium Iodide. Bring to 120 deg F.
Solution B:
Dissolve 12 grams of Silver Nitrate in 84 ml of water. Heat to 120 deg F.
Solution C:
18 grams of gelatin with excess water to swell (this should be kept below 68 deg F or the gelatin will begin to melt prematurely)
Precipitation:
Add B -> A in a fine steady stream with magnetic stirring.
Digestion:
Heat for 15 minutes at 140 deg F.
Final prep and washing:
Drain the water off the gelatin in solution C and when well drained pour the emulsion over the swollen gelatin. Mix well then heat until all of the gelatin is melted and well mixed. Chill set. You may then shred the emulsion and and wash for 30 minutes with 3 changes of distilled water.
Coating:
Add 4 ml of 5% Chrome Alum and 5 ml of 95% Ethyl Alcohol (Everclear). You may add one grain of Thymol as preservative. Coat at once on glass plates.
These plates can be used in-camera or to make lantern slides.
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