What Is Inkjet Ink Viscosity and Why It Matters?
Viscosity is one of the most important physical properties of inkjet inks. It determines how easily ink flows through the printer system and affects drop formation, nozzle performance, print quality, and system stability. Whether you’re using CIJ, TIJ, DOD, or high-resolution systems, maintaining proper ink viscosity is essential for reliable operation.
What Is Viscosity?
Viscosity is a measure of a fluid’s resistance to flow. In inkjet printing, it describes how thick or thin the ink is, typically measured in centipoise (cP). The higher the viscosity, the thicker the ink; the lower the viscosity, the more freely it flows.
Typical Viscosity Ranges by Printer Type
| Printer Type | Viscosity Range |
|---|---|
| CIJ (Continuous Inkjet) | 2–4 cP |
| TIJ (Thermal Inkjet) | 1.2–1.8 cP |
| DOD (Drop on Demand) | 8–20 cP (can vary widely) |
| HSPI (High-Res Piezo) | 4–12 cP (depending on head design) |
Why Ink Viscosity Matters
1. Print Quality
Too Low: Ink spreads too much, causing blurred characters or barcodes.
Too High: Ink doesn’t jet properly, resulting in drop misplacement or nozzle clogging.
2. Nozzle and Pump Performance
Proper viscosity ensures consistent ink delivery, reduces wear on pumps, and prevents strain on the system.
3. Temperature Sensitivity
Ink viscosity changes with temperature. Higher temperatures decrease viscosity, while cold environments increase it. Many printers automatically adjust for this using viscosity control systems.
4. Stability in Recirculating Systems
In CIJ and some DOD printers, viscosity impacts how reliably ink recirculates and maintains printhead pressure balance.
How Viscosity Is Measured and Controlled
- Online Viscosity Sensors: Installed in CIJ systems to continuously monitor and adjust ink formulation using makeup fluid.
- Manual Measurement: Using Zahn cups, flow cups, or viscometers in lab settings.
- Software Control: In advanced printers, firmware dynamically compensates for temperature or solvent evaporation changes.
Tips for Maintaining Proper Ink Viscosity
- Use only compatible makeup fluids (solvent/additive) provided by your ink supplier.
- Operate within the recommended temperature range for your ink type.
- Ensure ink is well-mixed and not expired or contaminated.
- Store inks in climate-controlled environments to avoid viscosity drift before use.
FAQs
- Can I dilute ink to reduce viscosity? No. Always use the designated makeup fluid. Water or other substances will alter ink chemistry and damage the printer.
- Why does my printer keep adding makeup fluid? It’s compensating for solvent loss due to evaporation, restoring viscosity to its optimal level.
Conclusion
Ink viscosity is a critical factor that directly affects printhead operation, drop accuracy, and print consistency. Proper viscosity control ensures your ink flows correctly, dries at the right rate, and produces clean, legible markings. Want help selecting ink with the correct viscosity for your system? Contact Cheef Inkjet today at sales@cheef.cn!
