Re: problem mixing argyrotype

I don't have experience with Argryotype, but I know sulfamic acid
solution does not keep very well. Sulfamic acid (amidosulfuric acid)
decomposes to ammonia and sulfuric acid if kept in aquaous solution
for a long time. Keeping property is worst at high concentration and
high temperature. If you used a stock solution of this agent mixed
some time ago, I suggest to use fresh solution.

From: ryberg <cryberg@comcast.net>
Subject: problem mixing argyrotype
Date: Sat, 18 Mar 2006 15:20:59 -0800

> Folks,
> I am trying to mix sensitizer for Argryotype following Mike Ware's
> instructions and starting with silver nitrate. I mixed the specified amount
> of silver nitrate in water, added the specified amount of sodium
> hydroxide/water solution and got a dark brown precipitate which I assume is
> the correct amount of silver oxide. This I filtered, washed and dried.
> Next I dissolved the specified amount of sulfamic acid in the specified
> amount of water and slowly added the silver oxide. It seemed to dissolve,
> giving me a brown liquid, however, when it sat a few minutes I realized it
> had not dissolved but merely formed a suspension which settled out. It is
> hard to tell, but I would guess that at least a third of the brown solid
> (presumably silver oxide) dissolved, perhaps as much as two-thirds. The
> rest has not dissolved after 6 hours.
> Should I add sulfamic acid, (assuming there is not enough to react with
> the silver oxide)?
> Should I filter and carry on with the addition of ferric ammonium
> citrate?
> Should I dump the lot and start over?
> Any suggestions will be appreciated.
> Charles, Portland OR
>
Received on Sat Mar 18 17:53:23 2006