U of S | Mailing List Archive | alt-photo-process-l | Re: ferri sesquichlorati

Re: ferri sesquichlorati

You all are great!

OK, so here is what it says:

Photo American, 1903, A Gum Bichromate Modification:
Dr. Lux has written about this in the Deutsche Photographen Zeitung.
Paper coated with a 12% hard gelatin containing "some acetic acid and some iron solution", the liquor ferri sesquichlorati (as you say, below) of pharmaceutical lore. It is added until the color of the mixture is such that a layer 2 mm thick makes white paper look distinctly yellow. Pigment then added as usual. Coating done thick and even at 112 degrees F. Expose and develop as soon as dry. Develop in dark in water til soluble iron salts are removed, and then do rest of gum print in light.

Now, of course, he says "gum or other colloid" and proceeds to talk about gelatin...

That's about it, and not very clear for sure!

I have also somwhere a person's process who uses silver nitrate in the gum.

But Halvor, it sounds like the same in Silver Sunbeam, which I have, so I'll check it out, and you say no luck with it...interesting. But I did think, one day, when accidentally using my cyano brush to brush a gum layer on, what would happen when it was mixed into the layer?

No mention of dichromate in this mix, though? Weird. Does the ferric chloride harden the gelatin?

----- Original Message ----- From: "Alberto Novo" <alt_list@albertonovo.it>
To: <alt-photo-process-L@usask.ca>
Sent: Wednesday, October 18, 2006 1:47 AM
Subject: Re: ferri sesquichlorati

Christina, sorry for being so late.
It's a latin pharmaceutical term, meaning Fe2Cl6. You can find also "liquor ferri sesquichlorati" for an about 30% solution. In a more modern term it is simply ferric chloride.
Help! Chemists, what is this "ferri sesquichlorati"? Ferric ammonium citrate? Ferric oxalate? Potassium ferricyanide??? I think it is a German word??