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

[Francesco Fragomeni]

All in all, I have the materials for testing the original formula's as well
as the variants I'm interested in. If I end up having problems I'll
probably just stick to the original formulas but hopefully this will be
relatively trouble free.

In the case of using the collodion for the base of a develop-out emulsion,
does anyone know if there might be any chemical reaction between the
collodion and Amidol? I would assume not but one can never be too sure.

-Francesco


On Thu, May 31, 2012 at 6:07 AM, Francesco Fragomeni
<fdfragomeni at gmail.com>wrote:

> Ryuji,
>
> Thanks for your thoughts. You're words are right in line with my
> assumptions. I'm no chemist but I have a basic understanding of what occurs
> when making these types of emulsions and while various different salts may
> have cause minor differences, I would assume that they are just that,
> minor. From my understanding, when an emulsion of this type is sensitized
> the NaCL and AgNO3 molecules exchange to produce silver-chloride (AgCl, the
> sensitive agent) and a non-sensitive byproduct that is typically discarded
> in the wash (sodium-nitrate, NaNO3). The only thing I can think of is that
> the Strontium-Chloride exchanges with Silver-Nitrate to produce
> Strontium-Nitrate which may lend itself to some specific color, perhaps a
> more prominent red that makes toning changes more evident. This is in line
> will what I've read, that Strontium lent a color that made toning easier to
> see. I'm still not sure about the alcohol solubility thing.
>
> -Francesco
>
>
> On Thu, May 31, 2012 at 2:03 AM, Ryuji Suzuki <rs at silvergrain.org> wrote:
>
>> I don't have experience with collodion process but in silver gelatin
>> process, the counter ions in the halide jet don't matter, as long as they
>> are alkaline metal or alkali earth metal ions, impurities are well
>> controlled, and the molar concentrations are adjusted. Those cations are
>> just wasted without participating in any reaction that forms silver halide
>> crystals. If solubility in alcohol is a factor, that may be one thing, but
>> then what alcohol concentration are you talking about? In silver gelatin,
>> sodium, potassium, and sometimes ammonium ions are used. Ammonium ions have
>> different effects on silver halide crystals in a pH-dependent manner, but
>> Na and K are largely irrelevant (in most cases, they are removed from the
>> emulsion before chemical sensitization phase).
>>
>> Emulsions that are used for printing out processes are very different
>> from emulsions for developed out processes. Don't underestimate that
>> difference.
>>
>> I also would not put too much emphasis on stuff written in old
>> literature, unless you can validate the statement with modern science.
>> Systematic research of how emulsion crystals are formed and what factors
>> have influence, etc., had to wait for sensitive instrumental amplifiers,
>> electron microscopes, and various laboratory equipment in the 20th century.
>> If certain issues or terminology disappeared in later literature, it might
>> be because the earlier debate became irrelevant under the light of new
>> science. THere are countless examples like that.
>>
>> --
>> Ryuji Suzuki
>> "When you're finished changing, you're finished." (Benjamin Franklin)
>> ______________________________**_________________
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>
>