[pure-silver] Re: Paperdeveloper for roller transport machine...contamination
----- Original Message ----- From: "Claudio Bonavolta" <claudio@xxxxxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, April 22, 2007 7:42 AM
Subject: [pure-silver] Re: Paperdeveloper for roller transport machine...contamination 



----- Message d'origine -----
De: "Dave Valvo" <dvalvo@xxxxxxxxxxxxxxxx>
Date: Sun, 22 Apr 2007 10:17:12 -0400
Sujet: [pure-silver] Re: Paperdeveloper for roller transport machine...contamination 
À: <pure-silver@xxxxxxxxxxxxx>
I just looked at this thread. RC paper does soak in chemicals from the edges. It is called "edge penetration". Some papers are worse than others depending on the paper design. The deeper the processor, the greater the pressure is from the chemicals and the greater the edge penetration. Then the squeezing of the rollers acts as a pump when pressure is released. RC papers if incubated will show yellow edges that rarely go beyond 1/4 inch. SO if you are concerned about edge penetration cut a quarter inch off the sides. BTW, Kodak had technology that prevented this from happening. 

You can NOT wash the paper to remove this.

Dave


Dear Dave,
Do you know what's the impact of the residual fixer in the paper layer of an RC print ?
Say, you overfix a RC print for an hour and then wash it carefully to be sure the emulsion has a low level of fix in it. Will have the fix in the paper the possibility to impact the emulsion layer through the plastic layer in-between or by other ways ? 

Thanks,
Claudio Bonavolta
http://www.bonavolta.ch
The question is whether anything in the paper layer can migrate through the plastic to the emulsion. I suspect the yellowing Dave mentioned is from decomposition of the residual chemicals _in the paper_ layer rather than in the emulsion, can Dave confirm this? On another topic, there are a number of other problems which RC paper proved to be vulnerable. One was the gas emmissions from the TiO in the reflective layer, another was decomposition and staining from residual developer in papers with incorporated developer. Kodak, Agfa, and Ilford seem to have found ways to cure all of these but I wonder if some of the smaller companies currently making RC have this technology. One reason Kodak's leaving the paper manufacturing field was such a disservice is that IMO Kodak had the most advanced technology of all. 

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