The problem of imprinting powder failure

Some substrates, especially polished coatings and clay-coated enamel products, have insufficient adhesion to hold the ink firmly on the surface of the substrate, tending to absorb only the varnish in the ink, whereas the gold and silver pigments The particles stay on the surface. In the printing process of the paper, after the ink is transferred onto the paper and dried, when the fingerprint is rubbed by hand, some of the marks are wiped off. This phenomenon is the fault of the imprinting powder.

The pulverization phenomenon causes the metal color to peel off from the surface of the substrate. The reason for the chalking of the prints is mainly due to the adsorption of ink in the connecting section in the capillary pores on the surface of the paper. In particular, the paper with loose paper has strong ink absorption. After the ink is transferred to the paper during the printing process, the ink connecting material penetrates into the paper more, so that some pigment particles cannot be surrounded by the connecting material. At the same time, it caused the imprinted powder, especially the use of self-made gold and silver inks, which is more prone to powder failure.

The main causes of chalking are:

1 The concentration of varnish is insufficient, and the content of penetrating substances is relatively high. Even if the texture of the paper is not very loose, excessive penetration of the connecting material may cause the imprinted powder.

2. Gold and silver inks are made from gold and silver powders and varnish. Powders and binders have poor affinity. When transferred to the paper surface, the excess binder was removed from the silver powder to penetrate the interior of the paper, causing chalking of the print.

In view of the above reasons, when printing gold and silver inks, the ink of the base ink must be printed first, and then the gold ink or the silver ink should be printed in an overprinted manner. On the one hand, the use of the background ink reduces the absorption of the gold and silver ink binders on the paper; on the other hand, printing the gold and silver inks when the ink of the background ink is not completely dry can enable the gold and silver inks to be firmly combined with the background ink, thereby avoiding the print chalking. . In addition, in order to avoid powder failures, the amount of water should be set to a minimum, because inks with higher water saturation are more prone to powdering.

When brushing on high coated paper or enamel surfaces, an appropriate amount of desiccant should be added to the ink. Before printing with gold or silver ink, the surface of the substrate is usually sealed with a conventional oil-based clear white ink coated with a glue. If chalking has already occurred, printing another layer of ink on the surface of the first layer will often compensate or reduce this phenomenon. Printing inks can also overcome powdering, but this will affect the metallic luster. For best results, it is recommended to use a metal plate instead of an electrostatic plate. This prevents the fountain solution from containing excessive amounts of glycerol or ethylene glycol because these non-volatile liquid media slow drying.

Source: Hui Yi Network