Application of Colorimeter in Printing Color Adjustment and Ink Adjustment

Color matching principle

In the actual measurement of the Colorimeter, we mark the measured data coordinate system as a static coordinate point (called the starting point). In the printing process, in order to ensure the stability of the hue of the printed matter, it is necessary for the ink mixer to adjust the ink ratio and viscosity at any time, so that after each adjustment and measurement, other coordinate points can be marked on the coordinate map (diluted point, point black plus point, etc.), there will be a certain moving direction and distance between the two different coordinate points formed before and after each adjustment (the distance along the coordinate a-axis and b-axis varies, depending on the product).

If we combine this value with the data such as Δa, Δb, ΔL, ΔE displayed on the Colorimeter, it will be displayed as a series of dynamic points on the coordinate system. Then, the direction and distance between these dynamic points are in actual In the operation, it becomes the qualitative and quantitative reference of which or which color inks and the added amount should be added by the ink mixing workers, which is equivalent to the compass and measuring ruler in the daily ink mixing work.

Printing toning ink skills and methods

With tools such as Colorimeters, even new employees can quickly get started in the ink adjustment work, and they will not be confused in theory, and veteran employees will be more at ease. Of course, in order to achieve such an effect, it is necessary to find out the coordinate points and dynamic points of each product on the coordinate map.

(1) Determine the adjustment direction and range according to the values ​​of Δa, Δb, and ΔL. If ΔL is a positive value, it means that the sample is whiter (less black) or lighter in color than the standard sample, and a negative value means that the sample is darker or darker than the standard sample (high ink color density or deep engraving of the printing plate, printing ink layer Thick); If Δa is positive, it means that the sample is redder than the standard, negative value means that the sample is greener (less red) than the standard; if Δb is positive, it means that the sample is yellower than the standard, negative Indicates that the sample is bluer (less yellow) than the standard.

(2) In the case where black dots need to be aggravated, ΔL changes in the negative direction, and when the ink is diluted or diluted or the speed of the printing press is increased, ΔL changes in the positive direction.

(3) Because the color of a transparent object is determined by the transmitted shade, and the color of an opaque object is determined by the reflected shade, therefore, when adjusting inks such as red, blue, green, and brown with strong covering power and clean and transparent For inks such as yellow, the change direction of the corresponding point coordinates Δa and Δb is opposite.

① After the red, blue, green, brown and other inks with strong hiding power are adjusted to increase the color density, the corresponding point will move to the center of the figure according to the speed of the printing press. The display is consistent; after adjustments such as speed-up, ink dilution or dilution, the corresponding point moves outward as the speed of the printing press deviates from the center of the circle, and the direction and size of Δa and Δb change are consistent with those displayed on the coordinate diagram.

② After adjusting the color density of inks with weak hiding power such as clean and transparent yellow, the corresponding points move outwards with the speed of the printing press away from the center of the circle, and the direction and size of Δa and Δb are consistent with those on the coordinate diagram; start the machine After adjustments such as speed up, ink dilution or dilution, the corresponding point moves toward the center of the circle with the speed up of the printing press, and the change direction and size of Δa and Δb are consistent with those displayed on the coordinate diagram.