The aim of this process is to reach a desired stock brightness by removing ink. Usually two flotation and thickening steps are required. During flotation, ash is lost to a certain degree. However, to produce a consistent paper quality, the ash content needs to be constant. Uncontrolled flotation would result in a higher consumption of ash to compensate for the loss, higher costs for the disposal of the ash removed by flotation, and more wastepaper to produce the same amount of product. Using Berthold’s density measurement solution to determine the ash content in the pulp, the deinking performance is optimized by keeping the ash content constant.

Customer benefits

  • Saves filler material
  • Keeps the ash content constant
  • Saves energy
  • Maximum use of recycled wastepaper fibers


  • Inline density measurement
  • Concentration of ash content 
  • Unaffected by the hostile ambient conditions
  • High measurement stability and endurance



Density measurement Product brochure

Englisch | PDF | 1.6 MB

Solutions for pulp and paper production Industry brochure

English | PDF | 1.2 MB

Berthold's Measurement Solutions

LB 379 Inline Density Meter

Inline density meter using low energy gamma Am-241 source