[pure-silver] Re: Selenium toning + Agfa Sistan

I squeeze it off, just like wash water.





Regards



Ralph W. Lambrecht




On 11/26/04 5:14 AM, "Malcolm & Sylvia Brickwood"
<m_s.brickwood@xxxxxxxxxxx> wrote:

> When using Sistan, I'm never quite sure what the proper technique for
> wiping off excess is. What's the recommended procedure? Sponge, coffee
> filter, shake???
> 
> Thanks -
> Malcolm
> 
> 
> On Nov 25, 2004, at 7:26 PM, Richard Knoppow wrote:
> 
>> 
>> ----- Original Message -----
>> From: "DarkroomMagic" <info@xxxxxxxxxxxxxxxx>
>> To: "PureSilverNew" <pure-silver@xxxxxxxxxxxxx>
>> Sent: Thursday, November 25, 2004 4:11 PM
>> Subject: [pure-silver] Re: Selenium toning + Agfa Sistan
>> 
>> 
>>> We may never get the complete story (Agfa doesn't have a
>>> research staff
>>> anymore either), but they are talking about Sistan working
>>> on silver salts
>>> produced through oxidation in the print's future.
>>> Remember, Sistan is
>>> applied to the print and should not be washed out
>>> afterwards. It is staying
>>> in the print to work on future silver oxidations, turning
>>> them into
>>> insoluble silver compounds. The text says that these
>>> compounds build the
>>> protective layer at that time.
>>> 
>>> Selenium and KBT will protect the silver from this
>>> oxidation by forming mor=
>>> e
>>> stable silver selenide and silver sulfide, respectively.
>>> Hence, Sistan has
>>> nothing to do work on in a fully toned print. However,
>>> these toner
>>> conversions are never 100%, and that's why I like the
>>> Sistan treatment in
>>> addition to toning.
>>> 
>>> IMHO, Sistan is not a replacement for toning as this
>>> brochure promotes. The=
>>> n
>>> again, using Sistan without prior toning is better than
>>> using no print
>>> protection at all. However, there are arguments that
>>> Sistan might not be
>>> needed if the print has been toned. I just like to be
>>> sure, and Sistan
>>> cannot hurt as a final treatment, if its residue is wiped
>>> off.
>>> 
>>> 
>>> 
>>> 
>>> Regards
>>> 
>>> 
>>> 
>>> Ralph W. Lambrecht
>>> 
>>> 
>>> 
>>    Sistan consists of Potassium thiocyanate and a wetting
>> agent (Triton-X). Thiocyanates were used as a stabilizer in
>> the old stabilization rapid processing system to prevent
>> decomposition of the halides left in the emulsion. I think
>> the function must be similar in fixed and washed prints. I
>> suspect the action is similar to that of a small residue of
>> thiosulfate in the emulsion. That apparently operates by
>> creating about a one molecule layer thick coating of silver
>> sulfide on the image silver. Silver sulfide is very stable.
>> It may have other functions, Agfa has never been very clear
>> about the theory behind it. Fujin makes a similar stabilizer
>> called Ag-Guard. This is not Thiocyanate, I don't know what
>> is in it. Fuji's published research shows Ag-Guard to be
>> effective in protecting silver images against oxidation and
>> sulfiding but not as effective as toning with a sulfide
>> toner.
>>    Its difficult to figure out what, if any, effect Sistan
>> or Ag-Guard has on toned images because there is no
>> published theory and there is no research data whatsoever. I
>> think both are useful where some protection is desired
>> without changing the color or density of an image but for
>> genuine archival lifetime sulfiding toners of the
>> Polysulfide type seem to be the best choice.
>> 
>> ---
>> Richard Knoppow
>> Los Angeles, CA, USA
>> dickburk@xxxxxxxxxxxxx
> 
> ==============================================================================
> ===============================
> To unsubscribe from this list, go to www.freelists.org and logon to your
> account (the same e-mail address and password you set-up when you subscribed,)
> and unsubscribe from there.

=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your 
account (the same e-mail address and password you set-up when you subscribed,) 
and unsubscribe from there.

Other related posts: