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

[Clarence Rhymer]

Hello Francesco and Ryuji,

I agree completely with Ryuji concerning POP vs. DOP and the pit-falls 
of old literature, but would like to note that there is *no wash *in 
making the Collodio-Chloride for POP.  Whatever one adds, stays in the 
mix.  I am not sure how one would wash it anyway.  Collodion and water 
just don't mix.  A very small amount of water is required, but not too 
much.  Collodion USP is about 25% Ethanol, 71% Ether and 4% 
Nitrocellulose.  If you use 95%  Ethanol in your Collodio-Chloride 
formula, you can figure out about how much water there will be in the 
final mix (some is used to dissolve the other ingredients).

I have no idea about the using Amidol, but assuming you can make the 
product at all, why not test it with one of the more common developers.  
Amidol is used with with Kodak Azo and Lodima to achieve a special 
look/workflow.  There is no guarantee that it will give the same result 
with another silver-gelatin emulsion even if it is similar in speed, 
etc. to Azo/Lodima, let alone a Collodion based one.

Fancecso, I am unclear as to why you want a developing-out speed contact 
paper?

Cheers,
Clarence



On 31/05/2012 7:07 AM, Francesco Fragomeni 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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