1、 Whiteness and absorbency of paper: the whiteness of paper is the basis of bright printing color. The ideal paper can reflect nearly all the color light, and the gray, black, cyan, red or other color biased paper will absorb part of the incident color light, which will affect the hue, lightness and saturation of the imprint. This is equivalent to adding some other inks in the ink, which shows the impure of excellent ink, thus giving people a feeling of darkening, turbidity and color deviation.
2、 Ink transfer and rolling process: color ink in the coating ink bucket and roller is not clean, mixed with other color ink, is bound to cause color deviation, also cause the color is not bright. Therefore, when changing colors, be sure to clean the ink bucket, ink roller and water roller, especially when changing dark colors to light colors.
3、 Ink over emulsification and additives: traditional offset printing mainly relies on ink balance to complete the printing process. According to the analysis of the transfer process of ink, the emulsification of ink is inevitable. However, the excessive emulsification of the ink will cause the printing color fade, aging and other phenomena, resulting in the reduction of color brightness.