The main reasons for printing color bias include the following aspects:
Ink layer thickness and viscosity: The thickness and viscosity of the ink layer directly affect the ink quality of the printed product. If the ink layer is too thick, the viscosity will increase, which will affect the uniformity of the ink color; If the ink layer is too thin, the ink color will be light and the visual effect will be poor. As the printing time increases, the ink temperature increases, and the viscosity decreases, so it is necessary to adjust the rotation angle of the ink transfer iron roller to maintain the uniformity of the ink color
Printing pressure: Printing pressure is an important condition for blot transfer. If the printing pressure is insufficient or uneven, it will lead to uneven ink color on the print. The ideal printing process is to obtain a uniform ink color through a uniform printing pressure on the basis of "three flats".
Roller quality: The quality and viscosity of the roller have an important impact on the ink color. The instability of the viscosity of the rubber roller will lead to the decrease of ink absorption performance, which will affect the balance of ink color of the printed product. Therefore, rubber rollers of stable quality should be used and cleaned in a timely manner.
Paper surface quality: The smoothness, absorption, whiteness and gloss of the paper all affect the color reproducibility of the print. Smooth paper absorbs less ink, whereas rough paper absorbs more. Therefore, it is necessary to adjust the ink volume and pressure according to the characteristics of the paper
Light variation: Different light sources, light intensity, and illumination angles will affect the identification of ink color. The correct light source and illumination angle are important conditions to ensure that the ink color is accurate.
Inaccurate overprinting: Inaccurate overprinting will lead to differences in the overprinting position of various color dots, resulting in visual color aberration. Therefore, the overprint must be precise to ensure that the printed hue meets the process requirements.
Temperature and humidity: The change of temperature and humidity will affect the transfer effect of the ink, especially in solvent-based inks. Controlling the temperature and humidity ensures that the ink fully covers the substrate and avoids the loss of color
pH: Too high or too low a pH in the printing shop will affect the transfer effect of the ink, resulting in color deviation. Therefore, it is necessary to control the pH value of the workshop to avoid poor ink transfer.
Dirty or clogged anilox rollers: Dirty or clogged anilox rollers can lead to poor ink transfer and affect the color effect. The anilox rollers need to be cleaned or replaced regularly.
Ink purity: The impurity of the ink can lead to unsatisfactory absorption of color light, which can affect the accuracy of color. Higher purity inks are required to reduce color casts.