----- Original Message ----- From: Shel Belinkoff Subject: Re: Kodak Portra and T400CN (WAS: Kodak Portra)
> Perhaps this has been asked and answered before, and if it has, I wasn't > paying attention. There may be some need or preference for me to shoot > some chromogenic B&W in a few months and I was wondering if any version > of the stuff has better archival properties than another, and if the > various emulsions are sensitive to processing techniques? Is, for > example, longer washing helpful, or processing at one temperature or > another? I think XP-2 is the proven one. I have XP-2 negs that are over a decade old, and still looking good. I have seen with my own eyes, T400CN film that has faded past usefulness, from a process which was "in control" with correct wash and stabilization. Select and Portra have yet to prove themselves. There are a myriad of causes of dye shifting or fading in processed negatives. Some are the fault of the processing, some of storage treatments and others are inherent or design and/ or manufacturing defects in the material. Temperature of the process on its own would have to be fairly extreme to affect dye stability. The processing temperature of the bleach, fix, wash and/or stabilizer would have to drop several degrees below the control limit before it became an issue. In a standard film processor, there would be alarms going off all over the place before a machine failure of this nature generated a dye instability problem. The most likely process errors to cause dye instability are under replenished or under oxygenated bleach, under replenished fixer, or under replenished/ carryover contaminated wash/ stabilizer. I don't know if any of the chromogenics are especially sensitive to process variations. However, my opinion is that if a machine is well maintained, in control and has clean and correct strength stabilizer, any problems with dye stability fall on the film. I realize this probably doesn't answer your question. William Robb - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
