For about 4 weeks now, I've had some VERY strange and inexplicable film fogging issues with Efke PL100 and PL50.
I was getting a very weird fogging on the film. It wasn't banding that is sometimes found in Efke/Adox films, it was an even fog covering the entirety of the fill 12x20 and 8x10 sheet. It registered as about 0.45 - 0.65 on the densitometer and as I said, covered the entire sheet. The boxes were brand new and the film still within date.
I tried everything to remedy and determine the problem, mixed up new dev, new fixer, and even used distilled, thinking perhaps my tap water had changed. I tried new trays, ordered new boxes of film, patched the heck out of my camera bellows, etc etc.
All in all I probably exposed and developed 8 sheets of 12x20 and 15 sheets of 8x10 trying to solve the problem.
Nothing seemed to work.
(ironically) a light bulb went off in my head.
I had recently swapped all the light bulbs in my apartment to use the newer coiled high efficiency bulbs. The whole apartment complex had given out free bulbs in order to be "more green".
So naturally I had changed out even the one light bulb in my darkroom and was now using one of the newer energy efficient bulbs.
So I got into the darkroom and let my eyes adjust to the darkness and then looked up at the turned off light bulb and it had a VERY bright glow even tho it had been off for a good 10 mins. In the total "darkness" I took out a sheet of 8x10 film and held it up close to the bulb, dev it real quickly, and bam intense fogging in the middle of the sheet.
Apparently, when I was in total darkness and loading my 12x20 and 8x10 holders, I was actually fogging each and every sheet as I loaded them.
I've since changed out the bulb and voila, no more fogging.
The newer energy efficient bulbs have the possibility of fogging film pretty badly. Be warned.
I didn't see any reference to this in my searches during the problem solving stages, so hopefully I didn't miss or overlook what has already been mentioned.