Brookfield Engineering

Flexographic Printing

Process Viscometer Application Data Sheet


Flexographic Printing, a major segment of the printing industry, is a primary application market for viscosity control.

Flexography is a printing process which uses a raised rubber or photopolymer plate with a rubber fountain roller or engraved chrome or ceramic anilox roller to carry the ink to the plate. It's a popular and lower cost method of printing than gravure.

Traditionally, Brookfield Engineering Laboratories has provided viscosity control instrumentation for solvent-based applications, but the major growth now is in water-based inks which have their own distinct problems.

This key application is for monitoring and controlling viscosity and pH in flexographic solvent and water-based printing inks during the printing process.

Problem Description

To assure the uniform application of water-based inks on a variety of substrates, it is necessary to control viscosity and pH. If flexographic water-based ink pH is not maintained within certain limits, an irreversible degradation of ink quality will occur. Failure to maintain the proper viscosity and pH settings for water-based inks can result in:

  • Ink, varnish and solvent additions that aren't properly proportioned
  • Higher costs due to using excessive ink
  • Colors being too dark or dense
  • Ink reservoirs requiring frequent viscosity or pH adjustments during press runs
  • Large fluid additions to reservoir will disrupt ink formulation
  • Longer press run times to correct or compensate for the above problems


  • Continuous monitoring and control of the ink reservoir viscosity using the Brookfield AST-100 or VTA-120
  • Automatic additions of proportioned batches of solvent or pH make-up fluid
  • Frequent additions of small batches will minimize ink solution disruption
  • Provide simultaneous viscosity and pH measurement and control at multi-stations
  • Integrate temperature measurement, when applicable

Qualifying Your Application

These conditions typically require viscosity control.

  • If you use gravure or flexo printing processes
  • If you roller coat solvent-based varnishes
  • If press runs are longer than four hours

Given one or more of the above conditions, ask:

  • How frequently are you checking your ink or coating viscosity?
  • How often are you making viscosity adjustments?

If you're making any of the above checks or adjustments every 15-30 minutes, you must consider viscosity control.


  • Saves money by using less ink
  • Optimizes printing quality and consistency
  • Assures that ink quality is maintained
  • Ensures continuity of color value
  • Provides cleanliness of image with no haloing
  • Maximizes press operating speeds
  • Prevents ink curdling due to wrong pH
  • Assures product consistency
  • Minimizes waste
  • Provides a permanent record for quality control, when used with recorder or PC


References include major boxboard converting companies and flexographic printing firms. Contact information will be supplied on request. For more details, contact your Brookfield Sales Manager.

Return on Investment

  • Save money on ink costs because of less waste
  • Better quality print jobs mean less rejected jobs
  • Less press downtime