When using fluorescent ink for printing, there may be a defect called "white gap" in the color effect of patterns with large color difference. In this case, hazard printing should be carried out. For example, when using yellow fluorescent ink for printing patterns containing black text on a large area, hazard printing should be carried out on the remaining colored parts except for the black text. The specific scope of the white gap to be filled is determined by the thickness of the strokes of the text to be processed and the area of the fluorescent ink printing of the pattern, generally between 0.015mm and 0.025mm. For patterns with wide lines and more ink, a larger value of white gap can be filled, which will not affect the overall color effect. However, for fine patterns and delicate strokes of text, it is necessary to control it below 0.020mm to prevent overall distortion.

With the wide application and technological advancement of fluorescent ink, the printing application of multi-color fluorescent ink is becoming more and more popular. In order to make the color effect of the product after printing better, it is necessary to accurately sort the ink colors during printing. Colored fluorescent ink should not be mixed with other inks, and should be strictly separated during printing. If a five-color printing machine is used, colored fluorescent ink and other four-color inks can be printed together at one time, but it should be noted that colored fluorescent ink should be printed last, otherwise it will be covered by other inks and cannot well present the characteristics of colored fluorescent ink. If a four-color printing machine is used, the ordinary four colors should be printed first and allowed to dry before printing the colored fluorescent ink.