[alt-photo] Collodio-Chloride and Collodion-Based Silver-Chloride Processes: Strontium-Chloride vs Sodium Chloride?

Francesco Fragomeni fdfragomeni at gmail.com
Wed May 30 14:54:08 GMT 2012

Hi all,

I have a question that I'm hoping someone may be able to help me with. I've
sent this same email to Denise Ross as well as Mark Osterman and figured
I'd present the same questions to all of you in hopes that someone here
might also have relevant information.

Based on my current environment and resources, I've decided to concentrate
my efforts on two variants of Collodio-Chloride processes. Specifically,
I'll be working with the Collodio-Chloride POP process (Aristotype Process)
described in moderate detail by Mark Osterman and I'm very interested in
working with a variant of Ron Mowrey's Silver-Chloride Azo-like contact
speed emulsion described in his book but substituting collodion in place of
gelatin. My question pertains to the use of Strontium-Chloride vs Sodium
Chloride in the Collodio-Chloride (Aristotype) process and subsequently any
advantage of substituting Strontium-Chloride for Sodium-Chloride in Ron's

I found a reference<http://books.google.com/books?id=05wOAAAAQAAJ&pg=PA385&lpg=PA385&dq=collodio-chloride+strontium+vs+sodium&source=bl&ots=wmj2uxrbas&sig=4YdMX2Fi_lYkH6jcoYKL7_xnwWo&hl=en&sa=X&ei=VSfGT9OtFcjv0gHa36mSCw&ved=0CEwQ6AEwAw#v=onepage&q=collodio-chloride%20strontium%20vs%20sodium&f=false>
of left page) c.1865 in the Journal of British Photography in which a
reference is made to using both Sodium-Chloride and Strontium-Chloride in
the Collodio-Chloride process. The description says that Sodium was used
first but subsequently Strontium was found to "answer better". There is
also a reference to a similarity to another formula using
Magnesium-Chloride and stating that other chlorides soluble in alcohol are
effective. I assume it may have something to do with solubility in alcohol?
Sodium-Chloride is soluble in both water and alcohol but perhaps
Strontium-Chloride is more soluble in alcohol and therefore more effective
with collodion? The preference is what I am curious about. Also, all of the
references that I found suggest that the preference may have something to
do with the subsequent color of the print and making observing toning
Either way, I have Strontium on the way in case I choose to compare it with
Sodium-Chloride. I'm not particularly interested in experimenting for the
sake of experimentation. I'm interested in finding an effective and
repeatable process to work with so if I an just get this answered by
someone who knows better then I then that would be hugely advantageous.

Regarding Ron's formula for the contact speed Azo-like emulsion in his
book, this is my priority and knowing if Strontium-chloride is more
effective in collodion then Sodium-Chloride becomes important to know.

>From all of my research, collodion appears to be a direct replacement that
can be used (and was found to be advantageous) in place of Albumen and
gelatin in most if not all Salted Paper processes so hopefully there will
be few if any obstacles but clarification on the Strontium-Chloride vs
Sodium-Chloride issue could be very useful and save me some wasted
materials and money.

If you have any information that may help clarify any of my questions
please let me know. Thanks so much!

Francesco Fragomeni

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