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  • Film has too Low Density

    I developing film output from an Agfa Accuset 800, in a Glunz & Jensen Mulitline 15 processor and my film density is too low. I have the exposure set as high as possible on the imagesetter (255).
    I've addressed all the possible causes in the processor's manual:
    - exhausted developer - mixed a fresh batch
    - developer too cold - increased temp of developer
    - developer time is too short - increased time
    - replenishment insufficient - increased values

    We normally mix the developer in a 1:2 ratio. Would increasing the ratio yield more dense film?

    Any help is appreciated.
    Thanks.

  • #2
    Re: Film has too Low Density

    Ok so what is remaining that you have not tested for...?
    bad film, bad imaging device

    try exposing 2 rectangles, one black, the other white with a 50% border, this should tell you if the film is OK, preferably this should be done manually, to remove the imagesetter from the equation, if you don't have a camera then you'll have to use old-fashioned masking and daylight. the 50% screen is more for reference and can be left off for a manual test

    if the film processes fine, no dust or pinholes in the solids, then you know the film is OK.
    once you know the film is OK, then you can run a greyscale/density test on your imagesetter.

    Comment


    • #3
      Re: Film has too Low Density

      A couple of questions for you.

      1. What is the density you are trying to get to?
      2. What is the film manufacturer?
      - Is it a matte tilm?
      - Is it .040 or .070?

      We still use an Accuset 1000 with all the filters turned off (full blast like yourself) in order to get to a density of 4.6 - 4.8. What made the difference for us (besides keeping on top of your chemistry) was the manufacturer of the film itself. You may also just have a laser that is on it's last legs.

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      • #4
        Re: Film has too Low Density

        Thanks for the suggestions.
        Unfortunately I do not have a camera. I'm not sure what the procedure is for the "old-fashioned" way of masking and daylight you mentioned, but I can tell you the end of the film that is exposed from the imagesetter's take-up cassette is totally dense, and is the density I'd like to achieve. Other than that the film looks OK.

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        • #5
          Re: Film has too Low Density

          Flexo,

          1. The density reading I'm getting is 2.089, and the reading I get from a fully daylight exposed piece of film is 3.088. (i'm not even sure if I'm using the densitometer correctly)

          2. the film manufacturer is #1 Network brand HN/VLD film. It is not matte. I assume you're asking about the thickness of the film, my calipers register it 0.035mm, so I guess that would be .040 (I don't see that information on the packaging)

          Thanks,

          Scott

          Comment


          • #6
            Re: Film has too Low Density

            > 1. The density reading I'm getting is 2.089, and the reading I get from a fully daylight exposed piece of film is 3.088.
            > (i'm not even sure if I'm using the densitometer correctly)

            Well, if you are using the densitometer correctly, a daylight exposed density of 3 is way to low. Density should be at least 3.5, and daylight exposed film should get much higher densities... way above 4.

            Maybe the film you are using is to old? Is there a manufacturing date on the box?

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            • #7
              Re: Film has too Low Density

              Another possibility is the optics, if they are dirty, you are not getting maximum light or perhpas the laser is on it's last leg of life and can not provide enough energy. The film manufacture should be able to provide you what the recommended D-max should be.

              Good luck,

              Mark Tonkovich
              Heidelberg USA
              Product Manager, CtP & Proofing
              Mark Tonkovich
              Heidelberg USA

              Comment


              • #8
                Re: Film has too Low Density

                We had a film density problem years ago. It turned out that the filter was closed so the developer was not circulating properly.

                Edited by: Mark on Jan 4, 2008 11:29 AM

                Edited by: Mark on Jan 4, 2008 12:21 PM

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                • #9
                  Re: Film has too Low Density

                  For years before we had a densitometer my method for testing the film density was holding it up to the light and if I couldn't see through it I was good to go.

                  Sounds to me like you might want to try another film supplier. I've being using ViTony graphics for about 10 years now with no problems.

                  We have an old Accuset 1500 for an imagesetter that works like a champ. Our old Ultre 3000 rollers literally melted away. I fought that thing for a long time on registration and my Bindery trained boss just couldn't understand what was going on.

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                  • #10
                    Re: Film has too Low Density

                    Hello Scott. It has been a while since we used a film processor. I know when we had problems with density 1 of the things we did was drain the chemistry tanks in the processor and clean them up. We would refill the developer tank manually. When refilling we started by using unmixed developer, not to fill the tank but partially, then we would pour in the mixed developer,2 to1, but use warm water to speed the process up. Once it was warmed up we started running test to check the density.

                    Comment


                    • #11
                      Re: Film has too Low Density

                      Hello Scott. It has been a while since we used a film processor. I know when we had problems with density 1 of the things we did was drain the chemistry tanks in the processor and clean them up. We would refill the developer tank manually. When refilling we started by using unmixed developer, not to fill the tank but partially, then we would pour in the mixed developer,2 to1, but use warm water to speed the process up. Once it was warmed up we started running test to check the density.

                      Comment


                      • #12
                        Re: Film has too Low Density

                        Hello Scott. It has been a while since we used a film processor. I know when we had problems with density 1 of the things we did was drain the chemistry tanks in the processor and clean them up. We would refill the developer tank manually. When refilling we started by using unmixed developer, not to fill the tank but partially, then we would pour in the mixed developer,2 to1, but use warm water to speed the process up. Once it was warmed up we started running test to check the density.

                        Comment


                        • #13
                          Re: Film has too Low Density


                          just a note about densitometers... there are several types, and there is one type designed specifically for film. So running out to the pressroom to borrow theirs is not likely to work properly if that's what you did.

                          The idea here is to test the film, which ever way works best for you, in a way that does not include the imaging device or the processor as a factor. if the film is bad +without+ the imaging device, the the device is not the problem, however if the film is OK

                          the processor speed is also a factor, but you'd need to know the film manufacturers specs for "dip-to-nip" in order to time it, the slower it is, the more time the chemistry has to act on the film, lowering your density. so you need to know that no-one changed the processor speed by accident

                          a dirty laser lens or underpowered or bad laser head would cause poor exposure of the film, but you would likely have noticed signs of this intermittently over time, perhaps banding, and/or laser power errors from your imager's console.

                          in the old days, we had darkrooms, screen tints, orange and ruby masking materials
                          if I had to test film I could make a mask with one rectangle exposed, another rectangle with a 50% screen tint and an unexposed section. expose it and hand process it and you have film that never saw either the processor or the camera, then you can say "yes, the film is good", or "no, the film is bad"

                          Usually what happens is an additive effect, where on person tweaks this, another tweaks that, next time some other thing, just trying to get by until you make the down-time to fix it, but by that time, no one remembered any of the tweaks. Eventually it reaches a point where there's only a very small margin for error and one change in your equipment throws it out of kilter.

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                          • #14
                            Re: Film has too Low Density

                            You need to bring in your film sales reps pronto and have them bring along test equipment for chemistry and film.
                            If as reported film at end of roll is black i think its a chem problem
                            Image setter lasers don't usually get weak, they just die and turn off.

                            Good luck

                            Comment


                            • #15
                              Re: Film has too Low Density

                              Just out of curiosity, have you tried changing your processor speed? Didn't see that mentioned. Could've missed it though.

                              Monkey

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