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Whether UV ink is completely cured determines the adhesion fastness of the printing ink layer, the reproduction of printing colors, and the glossiness of the printing ink layer. Therefore, it is important to make accurate judgments on whether UV ink is cured quickly on the production site.

If UV ink is not cured thoroughly, the adhesion of the ink layer is relatively poor. During the printing process, it can cause the printing ink layer to stick to the back of adjacent prints, resulting in dirty prints; At the same time, the surface of the ink layer is not resistant to friction and is prone to scratches in subsequent processing and use of printed materials, seriously affecting printing quality. In the process of large-scale on-site printing, due to the large amount of ink supply and the thick ink layer, the ink cannot be completely dried when the printed product is dried under UV light, resulting in the phenomenon of the surface layer of the ink drying and the bottom layer not completely drying. We call this the phenomenon of false drying of the ink. Especially when printing dark colors such as white and black on the spot, due to the slow curing speed, it is easy to produce false drying, leading to poor ink curing. On the one hand, this is because white can fully reflect all visible light, requiring higher energy during curing, making it difficult for white ink to cure; On the other hand, although black and dark colors can theoretically absorb all light, the blocking effect of pigment particles on light also hinders the deep curing of ink, which requires higher energy. Therefore, the curing speed of black and other dark color inks is slower.

After years of production practice, we have summarized various judgment methods, which can be roughly summarized as appearance observation method, physical testing method, and chemical testing method.

(1) Appearance observation method: The appearance observation method directly determines whether the UV ink layer has a bright surface without the use of any external tools. Generally speaking, a fully cured UV ink layer has a shiny surface.

(2) Physical testing method: There are two commonly used physical testing methods. Method 1: Lay a piece of paper on the UV ink layer on the surface of the printed product, press the paper with your hand, and rub it back and forth on the UV ink layer a few times. If damage is found on the surface of the UV ink layer on the printed product, then the UV ink layer is not fully cured. Method 2: Use a pin to scratch the surface of the UV ink layer on the surface of the printed matter, and then put it under a 200x magnifying glass to observe the scratches. If the scratches on the UB ink layer appear zigzag under the magnifying glass, it indicates that the UV ink layer has been completely cured.

(3) Chemical testing method: The chemical testing method requires the use of acetone solvent for testing. The specific method is to drop acetone solvent onto the UV ink layer. If it is found that the UV ink layer can be dissolved, it indicates that the UV ink layer has not been fully cured.

Those with printing experience know that poor UV ink curing during the printing process mainly occurs when printing thin film products, while poor ink drying is relatively rare in printing paper products. This is mainly because the surface tension of thin film products is relatively low, and ink is not easy to firmly adhere to the surface of these products.

The most thorough way to solve the problem of poor curing of UV ink is to switch to UV ink with faster curing speed; You can also switch to ink with higher color concentration to achieve the expected color reproduction with a thinner ink layer, that is, by reducing the ink layer and improving the curing efficiency of the ink, the ink can be completely cured. In some cases, it is also possible to improve the curing efficiency of UV ink by adding an appropriate amount of surface smoothness aids or curing aids without replacing the ink, achieving complete curing of the ink layer. However, in general, the method of adding additives is not recommended to prevent chemical reactions from occurring.

The weak adhesion of the printing ink layer is not always caused by the ink itself, but is also closely related to the surface performance of the printing material (such as unsuitable surface tension values for printing, improper surface treatment of the printing material, and powder shedding of the printing paper). When replacing or adjusting the ink cannot solve the problem and the printing material cannot be replaced, there is solution for printing enterprises to choose from：

Before printing the color ink, first apply a layer of transparent and adhesive medium by printing Improve the surface performance of the printing material, so that UV ink can adhere well to it. This plan is to print this ink hopper base oil in the first unit of the printing machine, using UV curing. The UV600 series Primer from Zhongrun can be used in this situation.

Once encountering ink misting problems during the production process, commonly used solutions include:

(1) Adjust the viscosity of UV ink, as different printing speeds of the printing machine adapt to different ink viscosities.

(2) Regularly clean the rubber roller to ensure uniform distribution of the ink layer on the roller and improve ink transmission performance.

(3) Control the printing speed. Excessive printing speed will increase the possibility of misting ink.

(4) The thicker the ink layer on the ink roller, the greater the probability of flying ink generation.

(5) Increase the air humidity in the production workshop appropriately, because when the air humidity is relatively high, the possibility of misting ink is lower.

(6) During the offset printing process, attention should be paid to the balance control of ink and water. In short, the phenomenon of ink misting may occur at any time during the printing process due to the contact and rotation of the two rollers, which requires operators not only to have a high level of skill in operation, but also to be familiar with the data and specifications involved in printing, and to minimize the probability of ink misting as much as possible.