Standard Finishing
4Over

Announcement

Collapse
No announcement yet.

GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

Collapse
Canon
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

    Hi there

    I think I have press problems with plates not staying wet enough to prevent back trap in lighter colours, could anybody let me know what the grain depth of a analogue (pre ctp) plate is compared to a ctp plate.

    Rough figures would be great so i can make a comparison. Or anybody who would like to put there points forward, it would be nice to get your opinion.

    Thanks Paul

  • #2
    Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

    Paul,
    I am facing the same problem. I just got a new pack of plates from Ptek and I am having issues also. These are analog plates but the grain is running dry! It causes staining on certain colors. After like 500 imps’ I get tone streaks all over the paper. I switched my fountain solution to a wetter lower viscosity type and they seem to run ok now. What appeared to be a press issue was really not. In my case. The water pick up level on my ink is high and pigment level is low so you can guess the rest.
    Logical thinking: Press was running good for a long time what changed? New Plates? New CTP system? Thermal Plates? IMHO this whole forced digital move has been a Pain.
    What type of press are you on?

    Comment


    • #3
      Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

      Hi there offset guy

      I run a Heidleberg 74 5 colour, we use fuji plates and basf novavit ink. I have found our plates to struggle to keep ink out of the non image areas causing toning on the blankets roller marks in tints at the return oscillation point and other problems, unfortunatley its difficult to get things changed without knowing 100% what the problem is. What fount did you change to ?

      Comment


      • #4
        Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

        Hi Paul,

        just out of curiosity. Which platesetter are you using?

        Regards

        Comment


        • #5
          Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

          The plate setter is a screen pt-r4000 and the plates are fuji brillia LH-PIe with fuji developer.

          any help?

          Comment


          • #6
            Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

            Hi all,
            Generally in CTP plates there has been a move towards substrates with a "finer" grain profile, you can see this from the major plate vendors: Ultrgrain, Multigrain, Flat Substrate etc. With a finer grain it is easier to achieve a better dot resolution and plate sensitivity.
            Conventional analog plates have, or had, a Ra value between 0,5 and 0,6, the grain on the above substrates would be in the region of 0,3 to 0,4.
            Jonathan

            Comment


            • #7
              Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

              The Ra (average roughness) values might answer part of the question, but what does that have to do with the streaks and blanket build up? What was the Ra of the PDI plates, the multi metal plates, where there was no grain at all? What about the waterless plates of Toray or Presstek, the polyester non image area. I'm not sure if there is a grain issue there. It seems to me that the Presstek plates, the Anthem, etc, with the microceramic non image area is another animal, and just needs more water on start up and maybe in general.

              John Lind]
              Cranberry Township, PA
              724-776-4718

              Comment


              • #8
                Re: GRAIN DEPTH OF CTP PLATES COMPARED TO ANALOGUE

                In answer to your above questions, the blanket build up is because a very small amount of ink is in the non image area of the plate, not enough to show up on a printed sheet but enough to build up over 2000 impressions or more. The lines I talk about are caused by the rollers having slight sideward play in there journals, so when the press oscillates fully one way the roller takes a bit longer to follow the distributor and a momentary dry line is created on the plate, when you change the reverse point these lines move. This is only my opinion based on what I see happening and i could be very wrong, but plate reps defend there product, so do ink reps and paper reps in my experience blame anybody they can, and its usually left to operators like me to sort out a solution and in the past 5 years the only major thing to change at my company was the move to ctp.

                Thanks everyone for the help and the opinions it helps a lot.

                Comment

                4OverStandard FinishingDuploSmartsoft (Presswise)AleyantCanonKBA
                Standard FinishingDuploAleyantCanonGraph Expo4 PeesLabelexpoKBAKBA4OverSmartsoft (Presswise)

                What's Going On

                Collapse

                There are currently 5431 users online. 115 members and 5316 guests.

                Most users ever online was 6,597 at 10:25 AM on 04-20-2018.

                Working...
                X