Factors Affecting the Gloss of Offset Printing Products

In offset printing, glossiness has a great influence on the visual effects of printed products, especially color prints, and to a certain extent determines the grade and level of printed products. What are the factors affecting the gloss of prints? Here we analyze and discuss the following four aspects.

First, paper and print gloss

Paper is the main factor determining the glossiness of printed materials, including the following aspects:

1. The smoothness of the paper

The smoothness of the paper is good, and the gloss of the printed product is good; otherwise, the gloss of the printed product is poor.

2. Ink absorption of paper

The ink absorption of the paper is too strong. The printing ink binder penetrates more into the paper, leaving less on the surface of the paper. The gloss of the printed product is lower and even dull because the gloss of the ink is mainly formed by the binder. .

3. Paper strength

Paper strength is low, powder fall off, hair loss is serious, when printing, ink and paper binding force is not high, the gloss of printed products is low or even luster.

Second, the amount of chemicals and print gloss

The amount of chemical used is also a key factor affecting the gloss of offset printing products. Generally, the amount of chemicals should be reduced as much as possible to ensure that the printed products are brightly colored, glossy and bright, and clearly printed.

Third, ink and print gloss

Leveling of ink

In the printing process, the leveling property of the ink is good, then the glossiness is good; the leveling property is poor, the drawing is easy, and the glossiness is poor.

2. The degree of ink flow

The flow of the ink is too large, the size of the print is enlarged, the dots are enlarged, the ink layer is thin, and the gloss is poor; the fluidity is too small and the gloss is high, but the ink is not easy to transfer, which is not conducive to printing. Therefore, in order to obtain better gloss, the degree of fluidity of the ink should be controlled, not too large nor too small.

3. Fineness of the ink

Ink particles are rough, and piles and other defects are likely to occur during printing. The printed products are also rough, diffuse reflection, and poor gloss. On the contrary, the gloss is better. When choosing the ink (especially gold ink, silver ink) should pay attention.

4. Viscosity of ink

Viscosity should not be too large or too small. Over the general assembly, the surface of the blanket and the printed product will be peeled and drawn. When the size is too small, the size of the print will be enlarged, and the ink layer will be thinner, which will affect the glossiness.

5. Dry form of ink

The same amount of ink in different dry forms, its gloss is not the same. In general, the oxidized conjunctiva dryness is higher than that of the osmotic drying because the oxidized conjunctiva has a large amount of binder material on the surface of the ink printed product, while the surface of the infiltrated ink product has less binder.

Fourth, printing pressure and print gloss

Pressure is the key to a good transfer of prints. Pressure is too high, prints are enlarged, and glossiness is weakened; pressure is too small and prints are not clear, which can result in dull prints. Therefore, under the premise of ensuring that the ink on the blanket can be correctly transferred to the printing material during offset printing, the minimum pressure should be used as much as possible so as to print the glossy printing product.

In order to improve the gloss of printed products, the following methods can be used.

1. Add water (No. 0 oil). This oil has a large viscosity and is thick and thick. It can adjust the density of ink, thicken the thin ink, and increase the gloss of printed products.

2. Add bright paste. Bright paste is processed from raw materials with high gloss, which can increase the gloss of the ink, but the amount should not be too large, otherwise it will reduce the drying speed of the ink, resulting in sticky, brushed phenomenon, affecting gloss.

3. Add a lighter. When some inks are too dark to meet the requirements of spot color printing, they need to be lightened. This will not only make the ink lighter, but also improve the gloss of the prints.




Source: Ke Yin Media, Guilin, Guangxi, China