Grain on 4x5 - could the cause be exhausted bleach?greenspun.com : LUSENET : Large format photography : One Thread
I have a lot of 4x5 color chromes that show a tremendous amount of grain in the skies, specially noticeable in transition areas between different colors in sunset scenes. The look, even under a 4x loupe seems to be "peppered", as if someone took a pen and dotted a different color over the background. Since a lot of this film was Provia and Velvia, I sent it to Fuji engineers for review, they had no explanation. (these scenes are all properly exposed)
An experienced darkroom guy told me that this occurs when the bleaching process is done using exhausted bleach. Here was his comments....
Itīs the bleach. What you see is SILVER that is not dissolved by the fix, because the bleach is not oxidized enough. We had the same problem in our lab years ago with Fujiīs Velvia, which is hardly the worst to fix and wash out. Making a new run from Prebleach on will remove the silver but can alter the color.
My questions to any experienced E-6 guys out there....
1. Would you agree this problem is most likely from exhausted bleach. I can email a small sample of a sunset to demonstrate what the problem looks like if anyone is interested.
2. If so, would running this through a second bleach fix the problem? What are the risks?
3. If you feel its not an exhausted bleach issue, what else can cause this?
Thank you all in advance.
-- Bill Glickman (firstname.lastname@example.org), April 02, 2001
The exhausted bleach explanantion sounds feasible, and a second go through the bleach and fix shouldn't harm the film. The wash and stabiliser will have to be repeated as well, of course.
I've only seen this effect in its extreme, when the bleach bath got contaminated and was almost useless. The film had an obvious grey mask to it as well as a grainy appearance in that instance.
Does your film show any veiling?
If it's not the bleach, then I suppose that incorrect storage of the film could have caused the problem (any strange colour shift might be a clue here), or it might also be reticulation.
-- Pete Andrews (email@example.com), April 03, 2001.
Bill, I have the same problem on some of my Velvias. They seem to habe been processed by the same lab on a particular year. When I got them back from the lab, I did not notice something was wrong. But years after when I decided to scan them, I found that the skies were full of black dirt and were almost impossible to correct (it is not limited to the skies but that's where it is the most annoying). I would be interested in hearing if there is a way to clean them too!
-- Paul Schilliger (firstname.lastname@example.org), April 03, 2001.
Here is a reccomendation from a e6 processor...any comments?
I suggest that if possible you have someone give an extended wash, say 10 minutes to remove any chemicals left in the film and to make the emulsion as receptive as possible, then give a bleach of 6 mins, a fix of 3 mins, a wash of 3 mins and finally a stab of .5 min. If that fails to work then I think you have problems unfortunately Thank you..
-- Bill Glickman (email@example.com), April 03, 2001.