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I have an article somewhere about mottle on the base side. I will look it up. It referred specifically to BTZS tubes but would be analogous to what occasionally happens to sheet film in any similar process. In some cases it is simply that there are some streak-shaped patches where some of the dyes have not come out - again due to direct contact with the tube wall. In other cases this dye residue is observed along with a slight difference in sheen. But I believe these defects can be remedied. The author of the article (Phil Davis) also indicated these defects almost never print.
Regarding DDX, it is very similar to TMax RS in its working properties. If you are processing properly with your Jobo there should be no need to switch to DDX or any other developer for that matter. Notably John Sexton uses a lot of TMax RS to develop TMax sheet films in his Jobo.
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If the mottle is on the base side, rewashing and then treatment in Photo Flo might fix the problem.
PE
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I am also using Beyond the Zone System method of exposure with the exposure calculator. It gives different times of speed for the drums for roll film and sheet film. But I will check with JOBO.
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The mottling or streaking is on the emulsion side. It can be seen even on 8x10 contact prints.
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Prewet and use a stop.
PE
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Is the example above the type of thing being discussed in this thread? This is a section from the top left of the sheet seen in full below - I upped the contrast to make the marks more obvious. This is a sheet of 8x10 HP5 that I exposed on Sunday and processed yesterday. It was processed in a Jobo 2830 print drum (with internal ribs), rolling by hand in a sink. There was no pre-soak; I used Rodinal 1:25 (16ml to 400ml) for eight minutes; water stop; fix for about 10 minutes; wash; hypo clear; then final wash for 15 minutes. When I saw the marks after the film was dry I washed it again and soaked in photoflo again but the marks were still there.
Very interesting to read Photo Engineer's remarks.
I've done a lot of HP5 8x10 in this tank and never had these marks before. I have always done a pre-soak, but this time I didn't bother, so that is the most likely cause in my mind.
I always use a water stop, but again it is interesting to read that Ron thinks stop becomes more critical as you go up in format. So perhaps the strange marks are from extra development happening due to uneven stopping of the dev. The marks are almost certainly occurring where the film base is in contact with the ribs.
Either way, both of these things are easy to do, so from now on I will be doing the pre-soak and using proper stop bath, at least for large format. Fortunately this was just a demo shot.
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No prewet and no stop. Those are two critical factors especially with large format and hand agitated in a drum as well. It takes time for developer to spread evenly across a dry sheet of film or paper. It spreads more smoothly over a wet sheet. Same thing with stop. It takes time for water to neutralize developer evenly. Acid does it quickly.
These problems are worse at short development times. Kodak mentions that in their B&W darkroom dataguide.
PE
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the back isn't getting sufficient fluid circulation to remove the anti-halation dyes uniformly--that's why you need the special jobos for film--this problem gets very big very fast when sheet size inreases....4x5 hardly a mottle...use the same type of tank for 8x10, you'll always notice some fingers in a uniform area...11x14...forget it...any tube will give you uneven dye removal---this can't be fixed after the fact either--believe me, I've tried...uneven dissolution cannot be remedied...the leftover dyes take on a set or somehow react with the chemistry and produce a permanent stain.
the jobo film tanks do a better job because they have a barrel shape that gets fluid back there--but they batter the film too and cause scratching and are still uneven sometimes. jobo people hate the truth because they spent so much money--so there will be haters hating after they read this.
even if they made a special film jobo for 11x14 films with a barrel shape, it would not work due to the forces involved--I'm pretty sure the 8x10 one can't work 100% of the time either given how the film is "held in place" and the size of the forces involved.
deal with it or figure a workaround like some smart people have done...or do trays...but then you'll get tray scratches....maybe hangers you need....too many chemicals!!!!
everything has it's problems.
Last edited by johnielvis; 11-21-2012 at 10:35 PM. Click to view previous post history.
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Well, these dyes should be removable somehow even if you need an acid or base solution to get them moving. They dissolve readily in water, acid or base.
OTOH, just like drying spots, if the film is not wetted evenly from the very start,there may be marks. You can get permanent marks just by placing a drop of water on dry processed film. The spot is not easily removed. Rewetting the entire negative, then drying after use of photo flo might help.
PE
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The actual image I am having problems with is on my website. Go to www.davefrieder.com and go to Manhattan Bridge. Then scroll to image that says "Full View" It should be noticeable as vertical streaks. ANY help with this would be greatly appreciated.
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