[pure-silver] Re: KRST (was Sistan and Senior Moments)
----- Original Message ----- From: "Adrienne Moumin" <photowonder2010@xxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, August 17, 2007 9:49 AM
Subject: [pure-silver] KRST (was Sistan and Senior Moments)
Humpf. Not sure who to believe at this point, Kodak or the speculators!!
So I guess I'll keep on using it 1:19; although I will test some reject prints w/the stronger dil. to see if there's a discernible color change. Better safe than sorry.
Not speculation at all but the results of extensive research by the Image Permamence Institute of the Rochester Institute of Technology.
I can't find the citation to the original research on KRST but its mentioned in a paper describing sulfite wash aids (1). This paper mentions the use of diluted KRST and points out that even with its use the vulnerability of microfilm to oxidative attack is greater when it is overwashed. The effect of overwashing was investigated by the IPI in the research leading to the report mentioned below, it was not a factor in the failure of KRST to protect the NEH microfilm or other microfilm found to have the same problems.
The RIT research was done for the National Endowment for the Humanities in 1991, the full title is: _Final Report to the Office of Preservation National Endowment for the Humnities 
Grant No. PS-20152-57_
_Sulfiding Protection For Silver Images_ James M. Reilly, Kaspars M. Cupriks, Image Permanence Institute Rochester Institute of Technology, March 38, 1991 

  Reprints are available from the IPI.
While this paper addresses microfilm and not printing paper there is enough similarity in the emulsions to think its valid for paper also. I also had several private conversations with Dr. Douglas Nishimura, a scientist at IPI with direct involvement in the research who stated to me that KRST at 1:19 was NOT completely effective for paper for the reasons stated for microfilm in the above document. A more effective treatment is a Liver of Sulfur type sepia toner. IPI concocted their own version intended to have low odor but packaged toners are quite effective. These include Kodak Brown Toner and Agfa Viridon of the second type. Kodak published formula T-8 is also effective. Kodak has published a paper on the use of KBT for microfilm protection. It is Publication No. A-1671, _Use of Kodak Brown Toner to Extend the Life of Microfilm_ available on-line from the Kodak site.
1, _The Effect of Salt Baths on Hypo and Silver Elimination_ R. W. Henn, Nancy H. King, J. I. Crabtree, Kodak Research Laboratories, 1956 "Photographic Engineering, Vol7, NOs 3&4, p.153ff This paper also has a considerable bibliography of research papers pertaining to fixing and washing. 

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
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