February 9, 2022

Purpose of measurements. Planning

The most important questions that need answers:

  • Within-sheet consistency/repeatability (within page variations) for solid color and tints
  • Consistency/repeatability between sheets in press-run (between page variations)for solid color and tints
  • Consistency between the printing press units in terms of printing variations
  • Consistency between printing press units for the halftone dot gain (TVI) curve.
  • Assessment of the potential occurrence of slurring/doubling issues
  • Checking the fit and quality of substrate transport
  • Assessment of the potential template effect and the effectiveness of oscillation as a counteracting method.

Planning: need to determine:

  • Substrate size, the bigger the substrate, the more complete and accurate the test.
  • Substrate type(s). It is important that this substrate is similar to your planned production.
  • Specific inks defined and supplied in necessary to ensure reproducibility when the press is reassembled in your facility.
  • Specific fountain solution, ensure this combination will be used for planned production.
  • Determine optimal exposure parameters, including the screen line and screen shape
  • Clearly define reference printing conditions for test form 1, use it for setting colorimetric targets.
  • Determine if wet and dry measurements will be significantly different and what potential target adjustments resulting from the drying process to apply.
  • Determine the correct measurement mode (M0, M1, M2, or M3). Most measurements will be relative, but it will be important to document so when the benchmark is reproduced in your shop, in order to accurately compare the two.
  • Very important to use an accurate instrument for measuring. Check the consistency of instrument in Instrument Inspector in order to determine the within instrument variation. Need to ensure the instrument is precise before making all of the required measurements. Don’t want to rule a press out if lack of precision is due to the instrument, not the press. When possible use an automated measurement device to minimize human errors. A solution like an Image Control from Heidelberg is ideal in this case. However, it must allow you to measure color strips placed at any location on the sheet. The automated system should enable the collection of spectral data and export in one of the commonly used file formats. If we do not have an automated system such as Image Control, eXact Scan is the best manual measurement device providing quick measurements.
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