Re: Chemist question for all of you who love to figure things out

Hello Christopher,

Potassium cyanide was used by some operators as a means of
clearing the plate, rather than the sodium thiosulfate method.
It was considered to give a more complete clearing of the plate.
(read that as a cleaner maximum density for the shadows)
The chemical was also used for cleaning images.

Have you ever tried the "electro-chemical cell" method for clearing plates?

What the Rinhart's are referring to is using potassium cyanide in
the gilding stage of the process. The key to creating brilliance in the
image can be found in the quote you provided:

"...some other things".

Those "other things" were well guarded secrets. They nearly always
consisted of carefully balanced metallic salts poured evenly over the
plate and heated with a lamp in the manner of gold gilding.

Levi Hill's method used a combination of Platinum and Iridium for fixing.

Good luck with your research.

all the best,

Phillip

>
> From: Christopher Lovenguth <chris@chrisportfolio.com>
> Date: 2005/06/02 Thu AM 12:47:34 EDT
> To: Alt List <alt-photo-process-l@sask.usask.ca>
> Subject: Chemist question for all of you who love to figure things out
>
>
> I've come across something recently about "brightening" highlights of a
> daguerreotype plate.
>
> Here is the text:
>
> "The daguerreotypist sometimes immersed the plates in a solution of
> potassium carbonate and potassium cyanide with "a little alum, borax and
> some other things" (Rinhart and Rinhart 1981
> <http://aic.stanford.edu/jaic/articles/jaic35-01-002_appx.html> , 188). This
> procedure may have brightened the highlights by slightly etching them."
>
> Can anyone tell me what chemical reaction is going on here in a way someone
> who doesn't really know chemistry would understand. Also does anyone have an
> idea of what not so dangerous and toxic chemicals could be used to maybe
> recreate the same reaction?
>
> Christopher Lovenguth
> www.christopherlovenguth.com <http://www.christopherlovenguth.com/>
> 917.721.4768
>
>
>
Received on Thu Jun 2 00:42:18 2005