A characteristic I have come across when processing out-of-date sheet film is that sometimes the edges of the image tend to process with more density than the center of the sheet. This does not appear to be fog, as the unexposed film base (hidden behind the slots in the film holder) is still clear after processing. I'm thinking that the emulsion is not taking the developer evenly. Should I do a longer pre-soak? Right now I am doing a water presoak of 2 minutes before tray processing in D-76 straight. Any advice or comments appreciated.
A longer presoak is not going to make any difference. The problem is likely either slight oxidation of the halides near the edges, or may be a problem with the film itself. You do not state the manufacturer. Perhaps PE can chip in here...
Well I shot a few more sheets (Plus-X, expired 1981) and did a four minute water presoak with constant interleaving in an tray, then developed normally in HC-110 dilution B in a tray, with constant interleaving, and whatever issue I had is gone. The negs look very evenly developed and no age fog at all.
No. Of course the film was in a sealed foil lined bag inside the box, just as it left the factory until I cut open the bag. I generally take sheets from the middle to start. So...I may experience artifacts towards the top and bottom, possibly.
On further reflection, I think my problem may have been agitation related, as the first sheets were not interleaved constantly, but intermittantly. The second perfect processing, I interleaved the sheets constantly, taking the sheet off the bottom and placing it on the top over and over and over until the processing time was complete.