Film Fogging Mystery...
Ok everyone, I need some help troubleshooting a fogging issue that is getting out of hand.
I am developing with FG7 Concentrate (obviously somewhat old, but only recently opened) in a large plastic bottle, about a gallon or so. The film in question is Tri-x 400 (either from kodak or Arista 400 Premium).
I first noticed the problem when I used a 5 roll tank, developing at 68F for 12 minutes, 1 +15.
SOME of the 5 rolls, not all, had some slight fogging that was maybe 0.15 higher than the normal FB+F
I thought maybe this was a manufacturer issue, or that my rolls had been fogged from heat, etc because they were old (nothing is older than 2 years and has never been exposed to direct heat for a prolonged period of time) even though that was unlikely.
I have gotten the issue randomly when using films in 2 reel tanks and 5 reels where sometimes all of the film is fogged and sometimes only one, and sometimes none.
I just developed 6 rolls in 3 separate 2 reel tanks for 12 minutes at 68F 1+ 15, I agitate for the first 30 seconds and then for 5 seconds every 30 seconds thereafter.
ALL SIX ROLLS WERE FOGGED, SIGNIFICANTLY. Possibly 0.20 or higher above normal FB + F. All of the tones are normal, the film does not appear over developed.
What the hell is happening? Could it be that only some films are somehow fogged? Could it be the developer? I don't have any consistent results that say it is either of these. I have developed 125 PX without any fog in this developer, and have developed some Tri-x without issue before... Any clues?
Another feature of the fog is that it does not continue all the way across the film. At the VERY edges of the film of the sprocket holes I can see unfogged film base. This makes me think it could possibly be due to the agitation, since the film is completely immersed in the developer, only the edges of the film covered by the reels could possibly be safe from agitation, but would it cause this much fog? The high values are however normal, so it could not be over agitation..
Changing bag or dark room for loading he reels? Which ever, non light tight some how?
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I just cut a piece of the film off ( which is washing now) and used my densitometer to measure the film base. The film base plus fog reading was 0.52, which is VERY high. I read about a 0.30 as normal FB + F on my other rolls of Tri-x.
Originally Posted by Rick A
I ruled that out when I had fog on only some of the rolls in a single tank as they were all loaded in the same space, which is a light proof changing closet built specifically for film loading.
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I'm inclined to agree with what Rick is suggesting, I would look at the loading situation. The variation could be due to the amount of time a loaded reel was waiting for the others, if the room or bag wasn't totally light tight, the edges may have been protected by the reel. All speculation at this point, but that's where I would start.
Hmm, that is possible I suppose, although after 5 minutes in the darkened room I still cannot see my hand in front of my face after my eyes adjusted. I will make sure to eliminate this. Annoying that I now have to work one roll at a time so as not to ruin a large batch at once..
Originally Posted by erikg
The negatives all look normal other than the 0.50 FB + F and im sure will all be printable and just fine, although its VERY annoying to have that added time, and I know some of that fog is going to ruin some of my acutance...
I'm assuming you are using plastic Paterson tanks. Are you sure that you are closing your tanks properly, and alternately, are there any cracks in the lids of the tanks? How are you agitating: inversion or using the twirler thingy? Make sure you invert.
Well maybe it's not the loading area. After 5 minutes, certainly after 10 you would see any light source strong enough to fog. Variation in the film stock perhaps?
If you are using Paterson Super System 4 Developing tanks, you will note that they have red rings on the top of the main section.
Those rings are affixed by some sort of adhesive - I have one tank where the adhesive gave way. That allowed the light-tight lid to come loose unexpectedly.
Once re-glued, that tank was fine.
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