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PDA.C 02 PEA - Module Print Evenness Analyzer

Ultrasonic Tester for Prediction of Print Unevenness/Print Mottle of paper/board via Multi-Sensor Measurements of the Wetting and Absorption Behavior of Liquids


  • Gathering of the profile / the distribution of printing process relevant surface parameters of paper/board like binder, pores, pigments, surface sizing by measuring the interaction between testing liquid and paper using a novel sensor
  • Main applications:
    • Prediction and determination of the reasons of print mottle with
      • coating base paper/board
      • printing paper/board uncoated
      • paper/board coated
      • Research & Development
      • Quality Assurance
      • Troubleshooting
  • Main user:
    • Producer of paper/board
    • Converter of paper/board
    • Chemical supplier
    • Machine building
  • General application recommendation: Comparison of similar products, for the proof of changes in quality within one grade or a trial with one changed parameter, mainly of coating base paper / board


  • R&D: efficient product design & optimization
  • Troubleshooting: fast and efficient determination of the reasons for production malfunctions (back trap mottle, water interference mottle, coating base paper investigations)
  • QA: avoidance of rejects as measured values are available immediately after production of a reel
  • Assessment of formation, in particular with board
  • Assessment of two-sidedness, filming degree / latex distribution in the coating
  • Reduce or replace requirement of test prints and image analysis
  • Absolute measuring results
  • Fast available results
  • Creation of an user specific mottle scale
  • Automatically calculated results, based on a correlation analysis: PEA Mottle-Rating
  • High statistical certainty by multi measurements and implementation of statistical methods
  • Measuring duration: preferably approx. 8 up to max 15 secs. (depending on aim)
  • Time requirement for a measuring series including sample preparation approx. 8 – 12 min.
  • Sensor: 32 pixels per 1mm², resolution: 25dpi
  • Average curve of 32 single curves available
  • Initial reading approx. 40ms after liquid contact
  • Volume of testing liquid: approx. 240ml
  • Assessment of reasons for mottle by using different testing liquids: e.g. water, fountain solution, ink jet ink, mineral oil
  • Widely user-independent results
  • Automatic self-test of the complete system prior to each measurement
  • User-friendly software
  • A single mouse click converts the analytical data to PDA format or exports it into MS Excel
  • Very easy to operate

PEA application „printability“

  • Assessment of the average quality by the average curve of all 32 sensor elements
    • coating base paper, uncoated paper/board
      • sized: surface sizing and surface porosity
      • unsized: surface porosity
    • coated paper/boar
      • porosity
      • covering, thickness of coating layer
      • coat weight
  • Assessment of the profile/distribution of chemical and mechanical surface parameters by evaluation of the scattering of the measuring values of each of the 32 sensor elements
    • coating base paper, uncoated paper/boar
      • sized: distribution of the surface sizing agent, distribution of the surface porosity
      • unsized: distribution of the surface porosity
    • coated paper/board
      • distribution of binder/porosity/pigments

pea principle


Measuring Principle  
Measuring Principle A paper sample is fixed with double-sided tape at a sample holder and is brought in contact with testing liquid in a measuring cell by the PDA.C 02 Basic Device. From the moment of liquid contact, it is radiated in the Z-direction with high-frequency low-energy ultrasonic signals with a frequency of 2MHz or 1MHz optional. The attenuation of the ultrasound changes as the paper reacts with the liquid. Uneven liquid reaction/ penetration from point to point results in different signal intensities at the different sensors. This variations are gathered point-dependent by a novelly receiver with a resolution of approx. 25dpi. The Mottle Rating, the Variance, the Mottle Index M and the Structure Dimension S are calculated by a personal computer.
PEA measurement of two unprinted coating base papers with different mottle tendency:
3D-Figure (intensity I; time t; position x) as well as Mottle Index M and Structure Dimension S
mottling1.png mottling2.png

weak mottle

strong mottle

Technical Data

  • Sensor: one line of 32 sensor elements, each 1mm x 1mm horizontally
  • Measuring frequency: 2MHz (for paper) or 1MHz (for paper and board)
  • First analytical value: approx. 40ms after liquid contact
  • Amount of liquid in insert: approx. 240ml
  • Testing liquids: any testing liquid of low viscosity
  • Results: PEA-Rating, Variance, Index M, Formationindex F
  • PC software: all common operating systems
  • Test data: ASCII-File
  • Operating voltage: 110V 60Hz / 220V 50Hz
  • Weight: approx. 5 kg (including Basic Device approx. 20 kg)
Download this file (ModulePEA_eng.pdf)PEA Leaflet[english]282 kB