Hi Nomad,
Burbank has a whole chapter on this process. He calls the variation you tried Couppier's modification. Also his instructions just use a few drops of silver nitrate solution as an intensifier in the gallic acid ( instead of AN of silver). Interesting reading!
Various instructions for development with gallic acid -- for other processes -- use silver nitrate to speed things up and intensify development and acetic acid to slow things down and keep highlights clean. Aceto-nitrate of silver is a sort of "shortcut" to add both at the same time.
When you read instructions for old processes, it's often possible to try them without using the more hazardous components. For example, elemental iodine was often used as an "indicator". It adds color, and when it has been completely converted during the sensitizing step, it indicates the sensitizing is done because the color is all gone. So it's convenient but not strictly necessary. I think you can manage to clean the plates without hydrochloric acid too. I'm a little skeptical about using gallic acid as a preservative.... if you end up experimenting along those lines, you might try tannic acid instead and see if it improves the keeping of the plates.
I still think I read a description of this process somewhere that had very long development times, replacing the gallic / AgNO3 developer every hour or two over a period of 10 or 12 hours. Not sure where I read that.
I can just see the thread title now:We have egg-laying ducks, so if I try this it will be with freshly laid eggs. I wish I had time to try it right now.... you've really piqued my interest!
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