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  1. #1
    bpm32's Avatar
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    Trouble with screen and tube

    I've been using cibachrome tubes with 4x5 film. I use a machine to roll the tube, although it's a unidirectional roller, so I have to turn the tube around every minute.

    After some great suggestions on here, I started using fiberglass screen cut just a bit larger than the film, and sandwiching the film and screen together before sliding it in the tube. (emulsion side up, or away from the screen)

    I think this is a great method, but more than occasionally I'll get a grid pattern from the screen left on the backside of the film. This, in turn, translates onto the paper when I'm ready to print the negative.

    Has anyone else run into this? Any suggestions for fixing this? Is it due to using a unidirectional roller, and maybe during the presoaking stage (6 mins) the water isn't being agitated enough to clear the halation layer? I almost feel like the cibachrome tube has such a narrow diameter that the film is rolled so tightly against the screen, the water can't get behind there to clear the layer.

    Thoughts?

    I appreciate any help you can send my way - grid patterns don't add a lot to my photos.

    Thanks!

    Brian

  2. #2
    bpm32's Avatar
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    Anyone have any suggestions at all?

  3. #3

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    I use a Jobo Print Drum for processing 5x7 and 8x10 negatives and it works fine. I used to use an old Beseler print drum on a motorized base. Both methods gave good results and no fiber glass screen.

    I suspect the screen is pressing against the film and chemistry is not getting to those areas. You are loading the film with the emulsion side facing toward the center of the tube and the backing facing the wall of the tube - right.

    If you are then the screen marks should disappear in the wash.

    Hope this helps - Mike

  4. #4
    bpm32's Avatar
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    Thanks a lot for your reply, Mike!

    I hold the film (Ilford Delta Pro 100) with the notches at the top right. I then place that on the screen and slide it into the tube. With the notches at the top right as I lay it down, that is emulsion side up right? (sometimes my brain goes haywire)

    I wash the film for 20 minutes... but it still won't go away. Should I wash it longer... or use additional methods of washing other than self-emptying tank?

  5. #5

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    I know this can be confusing, but with the notch at the top right hand side the emulsion is facing you.

    Washing for 20 minutes should clear the backing. So, a little more investigation. Are the screen marks clear, ie can you see through them? And a quick test, do they change if you re-fix the film.

    My gut feel says you loaded the film the wrong way round into the tube - but lets keep going

    - Mike

  6. #6
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    You don't say if you are washing the film in place in the tube or removing it and washing in a tray. You are probably seeing the remains of antihalation backing which is in contact with the screen. A short try wash in weak sulfite solution might remove the grid.
    Gadget Gainer

  7. #7
    bpm32's Avatar
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    The lines from where the screen was actually in contact with the film is clear. It's the empty spaces between the screen grids that is the value that it should be. To me, it does sound like I put this sheet emulsion side against the screen. But let me say again, just to make sure I have it right...

    I pull the sheet out of the sheet film holder. I feel the notches at the top right (on the short edge of the sheet). I place the sheet on the screen with the notches at the top right of the screen. I then curl then sandwich and slide it into the tube. (In short, I literally pull the sheet straight out of the holder and place it straight onto the screen, never turning it right to left, or flipping it.)

    Am I missing it - or isn't that the way it should go?

    I did try refixing it, but that didn't clear it up.

    I wash the film in a hanger in a tank. If this helps visualize the problem, the negative has those lines only in the middle 1/3 of the negative. If you hold the negative in front of you, the longest edge on the sheet would be vertical, the shortest edge would be horizontal. In that position, the grid appears halfway down the sheet in the horizontal position, or across the shortest distance of the neg.

    When I roll the "sandwich" and slide it into the tube, the neg naturally wants to uncurl. This tendency puts the most pressure against the screen at the point where the grid is showing on the neg now. (does that make any sense??) There are times I've noticed when I go to wash the neg - as water crosses over the negative at that spot, the water will cross over this section differently - you can almost see the grid pattern appear where the water will collect or bead across the neg. Is this shedding any light on the situation?

    Where would a good place be to buy this sulfite solution? I don't want much at all, in case this isn't the fix.

    Thanks a bunch for your patience with me on this.

    I've got a real mess.

  8. #8

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    The fact that the grid lines are clear means the the film was fixed OK. So hold off on getting the sulfite just yet. No matter how long you soak the film the sulfite bath will not help.

    You do seem to be loading the film in the tank correctly, but it is easy to become disoriented in the dark. What I would do would be to sacrifice two sheets of film. One to practice loading into the tube and the other to take a test shot and run through your process again.

    Mike

  9. #9

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    Could it possibly be stress marks from the pressure exerted by the film itself within the tank? I think we've probably all seen them on roll film.
    Do the marks appear if you don't use the screen?

  10. #10
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    Thanks again for everyone's reply so far...

    I've got a few sheets that I either felt like I scratched as I was putting them in, or an unexpected flash of light occurred (lightning bug!) while I was loading the film into the film holder. So I can practice with those. My process is so simple though - I can't see how I'm messing that up. But I'll give it a shot and see if it makes any difference.

    As for the stress marks - I didn't get these lines when I wasn't using the screen. The reason I started using the screen was to cut down (or reduce completely) the number of scratches that I got from sliding the film in and out of the tube. Using this screen, I no longer get any scratches, as long as I'm careful. It's interesting - sometimes I get these grid lines, sometimes I don't. Sometimes they're less noticeable... but on this last negative - they're VERY noticeable!

    It's kinda scared me from developing any more film until I get a better handle on what's causing this. I -really- like this method - the rolling in the tube method - but I obviously can't keep using it if it's going to do this. I know it's the screen, b/c the lines and grid pattern match up perfectly with the screen I'm using. I guess the question comes down to whether or not I'm laying the film onto the screen incorrectly. I figure if I'm loading the film holders correctly (never loaded one wrong so far), then I should be aware enough to load the tube correctly. (Pardon me - I'm thinking outloud now - maybe this would be more appropriate in my journal)

    Maybe I'll look for a different screen. The mesh I've got is very fine. If any of you use this method - what kind of screening are you using? Mine is intended for doors/windows, and it is fiberglass.

    Thanks for letting me vent.

    Brian

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