In daily printing operations, a common phenomenon has drawn widespread attention: when using identical ink, equipment, and materials while maintaining consistent printing parameters, subtle color variations often appear in printed items produced at different times of the day—morning, afternoon, and evening. The causes of this phenomenon and potential solutions warrant thorough investigation.
Our company's research indicates that fluctuations in ambient temperature are the core factor driving this phenomenon. Our company notes that temperature changes directly affect ink viscosity. Alterations in ink viscosity subsequently impact the nozzle's ejection force, ultimately resulting in color variations in the printed output.
Ink viscosity exhibits high sensitivity to temperature. When ambient temperature rises, ink molecules increase their motion, reducing internal friction. This leads to decreased viscosity and enhanced fluidity.
Conversely, as temperatures decrease, molecular motion slows, increasing internal friction and raising viscosity while reducing fluidity. Taking common water-based inkjet inks as an example, a temperature fluctuation of 5-10°C can cause viscosity changes ranging from 10% to 30%. This fluctuation range is sufficient to significantly impact print quality.
Regarding the specific mechanism: When elevated temperatures cause lower ink viscosity, increased fluidity leads to diffusion during nozzle ejection. Droplets accelerate, landing closer than intended, thereby increasing ink density per unit area and resulting in darker colors.