Dot Gain Poly Plates on SM52 4 color

Discussion in 'Heidelberg Printing Presses' started by Tdj_81, Dec 5, 2018 at 5:58 PM.

  1. Tdj_81

    Tdj_81 Member

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    So where would you start on dot gain off the press sheets of 20% all units .

    So say my plates dot is 50% and i put the plates on and take a print it comes up as 70%- ;)
    My ink is any color you want will say black at a density of —- 1.85 on the Densitometer
    Alcohol at 8% to 10%
    Impression is on enough to get a solid print .

    Where would you begin to look first , I want your opinion and why ?

    Thx in advance for your help ;)

    Will say
    Poly plates micro is .20
    metal plates micro is .15
    Blankets Packets to speci aswell —
     
  2. turbotom1052

    turbotom1052 Senior Member

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    If your intention is repeatable, quality impressions I would start looking to dump the poly plates and stick with metal. I know, I know they have come a long way with poly technology, but its still not even close to metal, unless of course your running down and dirty, quickie print, type jobs. Not to disparage that kind of work if its paying the bills,but I just don't think the savings work out to be worth the headaches. If your biznez is operating true printing presses as opposed to duplicator style presses then Id say that you're better off looking to save money elsewhere.
     
  3. Tdj_81

    Tdj_81 Member

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    Yeah definitely metals is the way to go but I just run the machines and plates what my company has to offer me to keep me in a job .
    This way is definitely cheaper the quality is the same if you have everything set up correctly with your graphic design side and your machine set up correctly,
    it’s definitely more work for the printer but once you know the tolerance of the press, inks,paper and poly plates you have the same outcome as metals.
     
  4. turbotom1052

    turbotom1052 Senior Member

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    What sort of press and what type of work are you doing? If we are talking about an AB Dick running mostly line work, with an occasional crappy halftone, then I suppose poly plates will work, but.... if your typical jobs include any sort of high contrast, high resolution halftones and duotones, in screenings any higher that 133 line Id say you will need metal, unless of course your a hang um and bang um shop.
     
  5. Tdj_81

    Tdj_81 Member

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    I’ve run metal plates in my old company I worked for and we have had metal plates here aswell to keep the factory going , quality isn’t a problem it’s solving my question . ;)
    Speedmaster 52 - 4 color — SM 52
     
  6. turbotom1052

    turbotom1052 Senior Member

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    Ok lets try this again. I think that I have offered a possible solution to your problem, but you just don't like my solution. I don't believe you will ever get the high resolution you seem to be looking for from a poly plate. After your last post where you mentioned that the press in question is a 4color Speedmaster I'm going to double down on my answer. Your company has obviously shown a willingness towards quality impressions by buying a Heidelberg Speedmaster. Why would you want to compromise the presses capabilities by cheaping out on the plates??? Poly plates are best suited for duplicator style presses running linework.
     
  7. Tdj_81

    Tdj_81 Member

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    Your solution is spot on ;) thankyou for your input .
     
  8. turbotom1052

    turbotom1052 Senior Member

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    there is one possible fix that would help if you choose to stick it out with the poly plates. 8 to 10% alcohol is a pretty high concentration. If you can't find a way to eliminate alcohol completely, then I would suggest you lower the percentage to under 5%. Too much alcohol will tend to wash out the ink a bit as it acts as a solvent. This washing out of the ink will require you to run more ink to arrive at the same color. The thicker ink films you will need to run, will have the effect of reducing your ink tack levels. Lower tack levels will result in more dot gain. Especially in the 50% area you mention.
     
  9. Tdj_81

    Tdj_81 Member

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    Thnx I’ll try reducing my alcohol again and reduce my ink output to compensate and see how it goes , I would very much love to change my ink set but I’ve been told I can’t change inks, have to keep with what we have even though I’m the only one using the ink set .
    I’ll let you know if it helps , climate is getting hotter here now so hopefully it doesn’t effect my print to much
     
  10. turbotom1052

    turbotom1052 Senior Member

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    I would suggest the tackiest ink set your current supplier sells that will print without tearing apart the coating on the paper you typically use. Higher tack inks will usually print with the least amount of dot gain. Heavily pigmented inks will tend to be of higher tack.
     

  11. alibryan

    alibryan Senior Member

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    What you're describing has to do with dot gain on press, not the type of plate that you're using. You can adjust for it with a plate curve, ink form roll pressures, and blanket packing. When everything is set up correctly; Poly plates can hold 175 line, or better...
     
    Last edited: Dec 10, 2018 at 1:11 PM
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