How to see the quality of the ink?

   The quality of the ink directly affects the correctness and stability of the color of the

printed product. The water-based ink used in flexographic printing has the characteristics of

low viscosity and low pollution. Ink management is mainly to realize the control of ink

color quality parameters through the detection of ink hue, tinting strength and light fastness

performance, and eliminate color shift from the source. Ink testing and related information

can be provided by the supplier, or can be tested by the printing company itself.

   Ink hue, tinting strength testing, hue, and tinting strength are the basic items of ink testing,

and they have a great influence on the color of ink. Hue is the specific feature of ink color,

which optically corresponds to light of a certain wavelength and frequency, such as: red,

yellow, and blue refer to the hue of ink. Tinting strength refers to the degree to which one

ink affects the color change of another ink. When mixing spot color inks, when the hue or

color of one of the original inks changes, the color of the spot color inks will change.

Therefore, it is very important to control the color of printed matter to ensure the correctness

of printing ink hue and the stability of tinting strength.

   For the detection of hue, for the newly provided ink, it is generally necessary to adjust

its viscosity to the viscosity of the upper machine, use the printing machine to make a sample,

and print the color sample of the ink with a solid plate, or put the ink on the color

development wheel with the pressure adjusted Drop a few drops, drag it on the surface of

the substrate with a certain pressure and speed, and print out a ribbon as a color sample.

Observe the effect of these proofs. If the ink layer is uniform and smooth, well-colored,

with a certain gloss, the ink color is thick, and the color is basically the same as the standard

color card provided by the supplier, it means that the hue of the ink meets the requirements.

Finally, a certain amount of ink for this test can be sealed and stored as a reference

wet color sample for the next hue test.

   For the detection of ink viscosity, the viscosity of liquid ink is relatively low and its fluidity is

relatively good. The method of detecting viscosity is also very simple. Only a viscosity cup

and a stopwatch are needed to complete the detection of ink viscosity. The specific operation

method is: first stir the ink evenly, then immerse the viscosity cup in the ink, and then lift

the viscosity cup out at a constant speed. When the viscosity cup is just pulled out of the

ink surface, press the stopwatch to watch the ink flow out; when the ink just has a break point,

press the stopwatch immediately. At this time, the time value on the stopwatch represents

the viscosity of the ink. If the viscosity is high, the seconds will be large; if the viscosity is low,

the seconds will be few. Due to the different temperature, the viscosity of the ink will also

change accordingly. Therefore, the general detection temperature is fixed at 25°C.