Printing process is an important part of packaging production, and it is inevitable to encounter printing color difference and other related quality accidents in the printing process. What are the factors causing printing color difference?

1、纸张白度：白度不同的纸张，对印刷墨层的颜色显现有不同的影响。对同一种白板纸而言，白度不同，印刷墨层的颜色差异主要体现在专色墨中黑墨成分的多少，尤其是对明度在70以上的颜色，影响特别明显，造成专色墨的配比差别很大。

1. Paper whiteness: paper with different whiteness has different effects on the color display of printing ink layer. For the same kind of whiteboard, the whiteness is different, and the color difference of the printing ink layer is mainly reflected in the amount of black ink in the spot color ink, especially for the color with lightness above 70, resulting in great differences in the proportion of spot color ink.

2、表面处理对颜色的影响

2. Effect of surface treatment on color

包装类产品的表面处理方式主要有覆膜、上光等。印品经过这些表面处理后，会有不同程度的色相变化和色密度变化。这些变化分为物理变化和化学变化。物理变化主要体现在产品表面增加了镜面反射和漫反射，这对色密度有一定影响。

The surface treatment methods of packaging products mainly include film coating, polishing, etc. After these surface treatments, prints will have varying degrees of hue changes and color density changes. These changes are divided into physical changes and chemical changes. The physical change is mainly reflected in the increase of specular reflection and diffuse reflection on the product surface, which has a certain impact on the color density.

3、撤淡剂对颜色的影响

3. Effect of desalting agent on color

撤淡剂是一种油膏状的无色透明物质，在专色印刷中主要起冲淡颜色的作用。撤淡剂的加入量不同，对色相的影响也不同，尤其是蓝色表现得明显。

Diluent is a colorless transparent substance in the form of ointment, which mainly plays the role of diluting color in spot color printing. The influence of different amount of diluent on hue is also different, especially blue.