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

Re: ferri sesquichlorati

Hi, No I did not have much luck with hardening gel with cyanotype alone.

Wares´s Cyanotype book page 57-8, got me interested on that, it is the "true
to scale" process, have seen it described other places too, apparently it is
the action of forming Prussian blue that can harden gelatine enough to ink
the gel and make prints from that.

The gelatine is however still, at least with my attempts, water soluble.

Else, I did a quick test today, mixing ferric chloride into a gum arabic
solution, which instantly turned it into "chewing gum", bit like dropping
platinum into gelatine... Assume that means that fe3+ hardens/crosslinks

If mixing tartaric acid into the gum solution, then mixing ferric chloride
into it, it stays liquid. Assume that means we get ferric tartrate instead
of "ferric-gum", Did a quick coating and exposure with that solution, but
the gum all dissolved in water. The pellet process says leave this solution
for 24 hours before coating, so left it and will try again later..

Will post when that is done, but may take some days...


On 10/19/06 11:32 PM, "Katharine Thayer" <kthayer@pacifier.com> wrote:

> On Oct 18, 2006, at 9:28 AM, Halvor Bjørngård wrote:
>> If you have Mike Wares Cyanotype book, have a look on the pellet
>> process. It
>> contains gum, ferric and tartaric acid. It is mentioned somewhere
>> in there
>> that Prussian blue can harden colloids, but have again not found
>> any closer
>> explanations.
> If by "Prussian blue" you mean what I mean by Prussian blue, the
> pigment PB 27 (hydrous ferric ferrocyanide, or sometimes
> ferriammonium ferrocyanide) then it definitely doesn't harden gum
> arabic, because I use it for a pigment in the gum process all the
> time; it's become my favorite blue.  Here's a test print made with
> Prussian blue.  It's not a perfect print; there's something weird
> with the coating or the sizing in one corner that flawed the print,
> but you should be able to tell from the rest of the print that
> Prussian blue acts just like any other pigment in the gum process.
> http://www.pacifier.com/~kthayer/html/Prussian.html
> I'm working on a page about bitmaps where you can see a better
> example, but I'm not finished with that yet.
> Katharine Thayer