| Pigment particle size | Sub-micron dispersion; commonly targeted below approximately 200 nm for the dispersed pigment system | Finer, well-dispersed particles reduce the chance of nozzle obstruction and sediment-related deposits. | Request particle-size distribution data, not only an average particle-size figure. |
| Viscosity at 25°C | Typically about 2–5 mPa·s, depending on the printhead and ink formulation | A controlled viscosity supports stable drop formation and helps prevent poor jetting or ink accumulation around the nozzle plate. | Compare the ink’s test temperature and method with the printer or printhead requirements. |
| Surface tension | Often approximately 25–40 mN/m for aqueous inkjet formulations | Balanced surface tension supports clean meniscus behavior, consistent drop release, and reduced satellite droplets. | Confirm compatibility with the printhead’s specified operating window. |
| Filtration level | Fine final filtration is commonly used; the exact rating must match the printhead design | Effective filtration removes agglomerates and foreign particles that could block narrow ink channels or nozzles. | Ask for filtration specifications and batch-control procedures. |
| pH stability | Commonly mildly alkaline, approximately pH 7.5–9.0; the acceptable range is printhead-specific | Stable pH helps maintain pigment dispersion and reduces changes in viscosity or surface tension during storage. | Check the recommended pH range and whether it remains stable after accelerated storage testing. |
| Humectant and moisture balance | Formulated with water-retaining components; the exact percentage is proprietary and printhead-dependent | Humectants slow evaporation at the nozzle plate, reducing crust formation during pauses and low-frequency printing. | Evaluate nozzle recovery after idle periods such as 8, 24, and 72 hours. |
| Sedimentation and redispersion | Uniform appearance with no hard sediment; gentle shaking or circulation should restore homogeneity when specified | Low sedimentation reduces the transfer of concentrated pigment particles into filters, dampers, and nozzles. | Request storage-stability and redispersion test results at the intended transport temperature. |
| Nozzle recovery after idle time | Should recover through the printer’s normal maintenance cycle without repeated aggressive flushing | Good recovery indicates limited drying, stable dispersion, and suitable evaporation control. | Test using the actual printer, printhead, capping station, and planned maintenance schedule. |
| Bacterial and fungal control | Preservative system and microbial limits should be documented in the technical or safety documentation | Microbial growth can create particles, odor, viscosity changes, and filter or nozzle blockage. | Request microbial test information and observe recommended shelf-life and opened-container limits. |
| Recommended operating environment | Typically controlled indoor conditions; many inkjet systems operate near 20–30°C and 40–70% relative humidity | Excessive heat accelerates evaporation and aging, while low humidity can increase nozzle drying and static-related dust contamination. | Use the ink and printer supplier’s specified temperature and humidity limits for final validation. |