How to Correctly Measure the Viscosity of Water-Based Ink

Date: Oct 17 2024 From: Star Color

The viscosity of water-based ink is a crucial parameter in the printing process, directly affecting the quality and effect of the printed materials. Therefore, correctly measuring the viscosity of water-based ink is an important step to ensure stable printing quality. This article will provide a detailed introduction on how to correctly measure the viscosity of water-based ink, including the required tools, operating procedures, and precautions.

I. Required Tools

Zahn Cup Viscosity Meter (No. 4): Compliant with GB/T 1723 national standard, with a measurement range of less than 150s.
Zahn-Kuhn Cup (Viscosity Cup): Compliant with ASTM D4212 national standard, with a measurement range of less than 80s. The Zahn-Kuhn Cup comes in five models, forming a complete set.
Stopwatch: For precise timing.
Glass Rod: For stirring the ink and scraping off bubbles.
200mL Measuring Cup: For collecting the ink flowing out of the viscosity meter's orifice.
Stopper: For blocking the orifice of the viscosity meter.
Thermometer: For measuring the ink temperature, ensuring it is within the range of 25±0.2°C.

II. Operating Procedures

Method 1: Zahn Cup Viscosity Meter Method

Preparation: Clean the inner wall and orifice of the viscosity meter cup, adjust the horizontal screw of the stand to make the viscosity meter horizontal. Place a 200mL measuring cup under the orifice of the viscosity meter and reset the stopwatch to zero.
Temperature Adjustment: Adjust the temperature of the well-mixed ink to 25±0.2°C.
Measurement: Use the stopper to block the orifice, pour the ink into the viscosity meter cup, and use the glass rod to scrape the bubbles and excess sample into the groove. Release the stopper and start the stopwatch simultaneously. When the ink stream breaks and the first drop appears, stop the timing. The time indicated by the stopwatch at this point is the viscosity of the ink.
Repeated Measurement: The test should be performed in parallel twice, and the difference between the measured value and the average of the two measurements should be less than 5%. If the condition is met, the average of the two test results is the viscosity of the ink sample.

Method 2: Zahn-Kuhn Cup Method

Preparation: Stir the ink sample for testing evenly.
Measurement: Dip the viscosity cup into the sample ink and then lift it out at a uniform speed. When the viscosity cup just pulls out of the ink surface, press the stopwatch to start timing, observe the ink outflow, and stop the stopwatch when the ink just has a breakpoint. The time value on the stopwatch at this point represents the viscosity of the ink. Higher viscosity results in larger seconds, and lower viscosity results in smaller seconds.

III. Precautions

Temperature Control: Since the viscosity of ink varies with temperature, the ink temperature should be controlled within the range of 25±0.2°C during measurement.
Cleaning Tools: The rotor or viscosity cup of the manual viscosity meter must be cleaned before use to avoid errors.
Measurement Environment: Measurements should be performed in the same temperature and humidity environment and must remain stable. Avoid vibrations or other interfering factors in the experimental environment.
Repeated Measurement: To ensure measurement accuracy, each measurement point should be measured at least three times, and the average value should be calculated.
Validity Period: The viscosity measurement of water-based ink should be performed within the validity period of the sample.
Instrument Selection: Choose the appropriate viscosity meter or viscosity cup for measurement according to the viscosity range of the ink.

Correctly measuring the viscosity of water-based ink is an important step to ensure stable printing quality. By selecting the appropriate measurement tools, following the correct operating procedures and precautions, the viscosity of water-based ink can be accurately measured, providing reliable parameter basis for the printing process. We hope that the introduction in this article can help readers better master the method for measuring the viscosity of water-based ink.