Understanding Viscosity in Small Character Inkjet Printer Inks

In Continuous Inkjet (CIJ) printing, ink viscosity plays a crucial role in determining print quality, droplet formation, and overall printer reliability. A deep understanding of viscosity management is essential for maintaining high-performance coding in industrial environments.

What Is Ink Viscosity?

Viscosity is a measure of a fluid’s resistance to flow. In inkjet printing, it describes how easily the ink moves through nozzles, forms droplets, and adheres to substrates. Too high or too low viscosity disrupts droplet formation, leading to poor print quality or printer errors.

Why Viscosity Matters in CIJ Printing

• Droplet Stability: Correct viscosity ensures consistent droplet size and accurate deflection onto the substrate.
• Print Quality: Stable viscosity maintains sharp, legible characters without smudging or blurring.
• System Health: Proper viscosity reduces stress on pumps, filters, and nozzles, extending equipment lifespan.
• Consistent Coding: Particularly important for variable data like expiration dates, batch numbers, and barcodes.

Typical Viscosity Range for CIJ Inks

Industrial small character inks typically have a viscosity range between:

• 2.0 to 4.5 centipoise (cP) at operating temperatures (usually 20°C–30°C).

The exact ideal viscosity depends on the printer model, ink formulation (solvent-based, MEK-based, pigment-based), and application needs.

How Viscosity Is Measured and Controlled

• Viscometer Measurement: CIJ printers are equipped with internal viscometers that automatically measure and monitor ink viscosity during operation.
• Solvent (Make-up Fluid) Addition: If viscosity rises above the target range (due to solvent evaporation), the printer automatically adds solvent to dilute the ink back to optimal viscosity.
• Alarms and Corrections: If viscosity falls outside the acceptable range, the printer triggers alarms (e.g., Viscosity Fault) and requires intervention.

Factors Affecting Ink Viscosity

• Evaporation: Continuous exposure to air causes solvent loss, increasing viscosity.
• Temperature Variations: Colder environments increase viscosity, while heat reduces it.
• Contamination: Dust, oil, or incompatible fluids entering the ink system can alter viscosity dramatically.
• Ink Aging: Old ink can lose its chemical stability, affecting flow properties.

Best Practices for Maintaining Proper Viscosity

• Ensure solvent reservoirs are filled regularly according to the printer’s prompts.
• Perform regular preventive maintenance, including cleaning filters and nozzles.
• Use genuine or approved inks and solvents to maintain chemical compatibility.
• Store consumables in controlled environments (temperature and humidity) to prevent degradation.

FAQs

• What happens if viscosity is too high? High viscosity causes poor droplet formation, missed characters, and increased nozzle blockage risk.
• What happens if viscosity is too low? Low viscosity leads to over-spraying, blurred prints, and unstable character shapes.

Conclusion

Maintaining the correct viscosity in small character inkjet printer inks is critical to ensuring consistent, high-quality printing and protecting your equipment. Regular monitoring, preventive maintenance, and using approved fluids will optimize printer performance and extend machine lifespan. Need professional advice on viscosity control or ink selection? Contact Cheef Inkjet today at sales@cheef.cn!