Mprice
Member
So, as the title says, I've recently started having some troubles with my negatives and thought someone here might have the solution. Some quick background info:
I've been developing my own negatives (B&W - 35mm, 120) on and off for about the last 15 years, always with steel tanks and reels - never had anything but great negatives. About 6 months ago I got decided that I had had enough of the hand agitation and that it would be great to be able to use my Unicolor base to do more rolls at a time.
I started with a Unicolor film drum and reels which worked out alright for 35mm but left streaks along the edges of 120, something to do with the reels apparently. I switched to Jobo and am using the 2500 series tank that holds 5 35mm rolls. Overall the negatives are coming out alright but I'm noticing that there are portions of uneven sky in my 120 and last night found surge marks from the sprockets on my 35mm. I initially thought it must be from over agitation as the base is always spinning but after some hunting around it appears that these marks really come from not enough agitation. The strange thing is that there doesn't seem to be any pattern to the portions of the roll that have the problems. The base reverses and the one thing I can come up with is that maybe because of the amount of rotation between reversing (due to the size of the drum, maybe 1-1/8 rotations) a portion of the roll is getting too much or too little of something. If this is the case, anybody know if modifying the base to not reverse will help (do Jobo systems reverse?)? One other idea would be to modify the base so it spins further, no idea how or if that's possible.
More info:
Tri-X 400 - 35mm and 120
D76 1:1 (freshly mixed last week, stored airtight, etc) - 10 minutes
Stop - 45s
Fix 1:4 (fresh as well) - 7 minutes
Any ideas or help would be greatly appreciated....thanks.
I've been developing my own negatives (B&W - 35mm, 120) on and off for about the last 15 years, always with steel tanks and reels - never had anything but great negatives. About 6 months ago I got decided that I had had enough of the hand agitation and that it would be great to be able to use my Unicolor base to do more rolls at a time.
I started with a Unicolor film drum and reels which worked out alright for 35mm but left streaks along the edges of 120, something to do with the reels apparently. I switched to Jobo and am using the 2500 series tank that holds 5 35mm rolls. Overall the negatives are coming out alright but I'm noticing that there are portions of uneven sky in my 120 and last night found surge marks from the sprockets on my 35mm. I initially thought it must be from over agitation as the base is always spinning but after some hunting around it appears that these marks really come from not enough agitation. The strange thing is that there doesn't seem to be any pattern to the portions of the roll that have the problems. The base reverses and the one thing I can come up with is that maybe because of the amount of rotation between reversing (due to the size of the drum, maybe 1-1/8 rotations) a portion of the roll is getting too much or too little of something. If this is the case, anybody know if modifying the base to not reverse will help (do Jobo systems reverse?)? One other idea would be to modify the base so it spins further, no idea how or if that's possible.
More info:
Tri-X 400 - 35mm and 120
D76 1:1 (freshly mixed last week, stored airtight, etc) - 10 minutes
Stop - 45s
Fix 1:4 (fresh as well) - 7 minutes
Any ideas or help would be greatly appreciated....thanks.
Penceler
Established
Hard to understand - particularly with tri-x. FWIW I would be thinking chemistry as opposed to agitation issue. Have you had this problem with multiple batches of chemistry? Also, can you post an example?
John
John
Finder
Veteran
I have a Jobo CPP-2 processor. The processor makes several rotations before reversing.
Mprice
Member
Thanks for the help, been out of town and hadn't gotten to reply. I think that for now I'm going to do some development by hand to see if that alleviates the problem, we'll see what happens...