Valmet IQ Total Ash Measurement

The accurate scan averages and high-resolution CD profiles measured by Valmet IQ Total Ash Measurement (IQ Total Ash) provide a solid foundation for Valmet’s machine-direction total ash content controls. Digital signal processing, and high-speed air density temperature compensation ensure superior measurement accuracy in hot, humid and dirty papermaking environments. IQ Total Ash measures total ash in papers containing clay or other fillers.


X-ray radiation from an Fe55 nuclear source is preferentially absorbed by the inorganic material in a paper sheet. As ash content increases, transmitted radiation that is captured by the ion chamber detector is reduced. This basic measurement principle is refined by using special sensor-design techniques and measurement diagnostics to provide the stable, high-resolution measurements needed for precise control. Ash content is factory calibrated for sheets containing clay or calcium carbonate or titanium dioxide.

Normal, radioactive decay is nullified by an automatic standardization sequence.
The effects of air density changes are measured and automatically compensated using high-speed air temperature measurements. In addition, temperature measurements within the source and detector heads monitor the internal sensor environment for diagnostic purposes. Using a real-time gap measurement sensor, the effect due to possible source-detector gap distance variation is automatically compensated.


  • Accurate and stable on-sheet measurements for precise control of ash content in paper.
  • Ash content can be optimized to improve quality and reduce furnish cost.
  • Faster on-spec quality and reduced startup waste.
  • Coat-weight control by ash difference measurement method.