ColorFlow Training

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Background

The flexographic printing technology uses a flexible relief plate to transfer inks from a cylinder to a substrate. The flexographic print response is controlled by the highlight gain and minimum printable dot. The minimum printable dot is accomplished by using Mindot bump and cutoff curves. This activity is to control the response of a flexographic plate by using Mindot bump curves.

Tasks

Goal
Create a print transfer curve to control the response of a Kodak Flexcel NX plate.

Task 1: Create a print transfer curve with a mindot bump for a flexographic printing plate

  1. In ColorFlow, click the Print Curves tab.
  2. In the Transfer Curves section, click the Add button .
  3. In the Name box, enter XX Flexo transfer curve (where XX = your initials).
  4. Ensure that the Show in Prinergy check box is selected.
  5. In the Device Conditions section, choose Flexographic Press for the Device Type and leave all the other settings as default.
  6. In the Curve Channels section, in the Process Inks list, select One channel for CMYK+. 
  7. Option 1: Define a preset curve shape for Flexcel NX plates, based on a midtone gain measurement (choose this option if you use Miraclon Flexcel NX plates.) 
    1. In the Curve Definition section, choose Flexcel NX Preset for the Curve Origin (talk to your Miraclon service representative to learn more about Flexcel NX Media Preset curves)
    2. In the Midtone Tone Value Increase box, enter the measured midtone gain, e.g. 15%.
  8. Option 2: Define a flexo transfer curve based on input and output values (choose this option for other flexo media)
    1. In the Curve Origin list, select Tint In/Out Points.
    2. Click the Tint Set  button.
    3. Click the Add button .
    4. Enter 10 25 50 75 90.

    5.  Enter the following Tint Out values:

      108
      2523
      5047
      7572
      9087
  9. In the Mindot Bump/Cutoff > Process Inks (CMYK) section, enter the following:
    • In the Tint In box, enter 0.39 (minimum system value)
    • In the Tint Out box, enter 2 (minimum printable dots on this type of plate)
  10. Leave the Highlight Contrast as the default value, if active (for Flexcel NX Preset only). This value can be adjusted to give the desired adjustment slope.
  11. Click Apply.
    A single-channel print transfer curve for flexographic plates is generated. It is named XX Flexo transfer curve.

Task 2:  Output a page using the print transfer curve in Prinergy

  1. In Prinergy, create a new job, and name it as XX Flexo plate (where XX = your initials).
  2. Refine Chart_TintRamp_CMYK.pdf with 1stRef-Normz.
  3. Output the PDF file using Virtual Proof.LoosePage with the print transfer curve you just created:
    1. In your Virtual Proof.LoosePage Process template dialog box, from the Output To list, choose Virtual Proof.
    2. Leave ColorFlow Color Relationship Management unchecked.
    3. Expand the Calibration & Screening panel.
    4. Select the ColorFlow Current State radio button.
  4. Midtone values will vary, depending on whether you chose a Flexcel NX Preset for Curve Origin or Tint In/Tint Out values. 
    1. Expand the Print Curve drop down list and choose curve XX Flexo transfer curve.
  5. Open the generated page in VPS and measure the 1%, 2% and 5% cyan patches. 
    Confirm that the print transfer curve has been applied:
    1. OPTION 1: for the Flexcel NX Preset curve, 1% measures 2.5, 2% measures 3.0, and 5% measures 5.3. 
    2. OPTION 2: for the Tint In/Out Points curve, 1% measures 2.6, 2% measures 3.2, and 5% measures 5.6. 

Outcome

You have created a print transfer curve with a minimum printable dot that controls the highlight and tonal response of a flexographic printing plate.

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