[pure-silver] Re: b&w print has discolored - re:Richard's comment on washing

What Richard said here makes me wonder about another practice of mine. Here's how I wash my prints. I wash off the back side of the print just a few seconds, then I lay the print, image side up, on an inverted tray under the stream of water in the deep sink. It washes there for several minutes. But what about any residue I'm leaving in the underside of the paper?
I've only been printing in my own darkroom since (I think) 2002. I'll look through my oldest prints, but I don't recall seeing problems in them over this length of time. There is one in particular that I could, under no circumstances, duplicate. I wouldn't want that one to go bad. I took special care fixing and washing... as I washed. But am I washing insufficiently without the water circulating to the backside? I don't have a "proper" print washer, like they had in the darkroom class I took - neither do I have room for one in my small darkroom.
Oh, and I'm glad I never ordered double-weighted fiber but once. Yikes! That's a lot of water. 

Janet




On Mar 27, 2008, at 10:48 AM, Richard Knoppow wrote:


At 05:25 AM 3/27/2008, you wrote:


On Mar 27, 2008, at 4:48 AM, Tim Rudman wrote:


However, you say you didn't selenium tone the print because it was
RC. Why?
You will still give protection with selenium , (or polysulphide or
gold)
with RC papers. It doesn't have to be used only with FB.
Tim


I didn't know there would be any affect, toning resin coated paper.
Thank you!  And I didn't know it gave any kind of protection.  I
thought it was just for sort of a color change.

Janet
The rate of a diffusion process is mostly controlled by the difference in concentration of the ions to be washed out in one side versus the other. So, for instance, the hypo left in the emulsion after fixing leaves pretty rapidly when fresh water is used for washing. The paper support, OTOH, washes out only partly by diffusion. some of the hypo gets trapped in the fibrous structure of the paper and moves out very slowly even when a wash aid is used. For protected support, meaning RC, the support does not absorb anything and washing time is whatever is sufficient for the emulsion. Most RC papers will wash out to "archival" levels in about 4 to 5 minutes in running water. 


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