Factors affecting the color difference of spot color in printing

专色印刷大量使用在画册印刷中，专色印刷的产品色彩鲜艳，减少网点叠印、网点变形，颜色稳定，专色印刷也容易产生色差，那么导致专色油墨产生色差的因素有哪些呢?

Spot color printing is widely used in album printing. The products of spot color printing have bright colors, reduce dot overprint and dot deformation, and the color is stable. Spot color printing is also easy to produce color difference. What are the factors leading to the color difference of spot color ink?

1.纸张对颜色的影响

1. Influence of paper on color

纸张对墨层颜色的影响主要体现在3个方面。

The influence of paper on the color of ink layer is mainly reflected in three aspects.

(1)纸张白度：白度不同(或带有一定颜色)的纸张，对印刷墨层的颜色显现有不同的影响。因此，在实际生产中应尽量选用白度相同的纸张印刷，以减小纸张白度对印刷颜色的影响。

(1) Paper whiteness: paper with different whiteness (or with a certain color) has different effects on the color display of the printing ink layer. Therefore, in actual production, paper with the same whiteness should be selected as far as possible to reduce the influence of paper whiteness on printing color.

(2)吸收性：同一种油墨在相同条件下印刷到吸收性不同的纸张上时，会有不同的印刷光泽。非涂料纸与涂料纸相比，黑色墨层会显得灰、无光泽，并且彩色墨层会产生漂移，由青色墨和品红色墨调配出的颜色表现更明显。

(2) Absorbency: when the same ink is printed on paper with different absorbency under the same conditions, it will have different printing luster. Compared with coated paper, the black ink layer will appear gray and dull, and the color ink layer will drift. The color mixed by cyan ink and magenta ink is more obvious.

(3)光泽度与平滑度：印刷品的光泽度取决于纸张的光泽度与平滑度。印刷用纸的表面属于半光泽表面，尤其是涂料纸。

(3) Gloss and smoothness: the gloss of printed matter depends on the gloss and smoothness of the paper. The surface of printing paper belongs to semi gloss surface, especially coating paper.

2.表面处理对颜色的影响

2. Effect of surface treatment on color

画册印刷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。覆亮光膜、光油和UV油时，色密度增加;覆亚光膜、罩亚光油时，色密度降低。化学变化主要来自覆膜胶、UV底油、UV油内含有的多种溶剂，它们会使印刷墨层的颜色发生变化。

The surface treatment methods of album printing products mainly include film coating, polishing, etc. After these surface treatments, prints will have varying degrees of hue changes and color density changes. When covered with bright film, varnish and UV oil, the color density increases; When the matte and oil film are coated, the density decreases. The chemical changes mainly come from a variety of solvents contained in film covering glue, UV primer and UV oil, which will change the color of the printing ink layer.

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 kind of colorless and transparent material 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.