For UV flatbed printers, there are two printing technologies, one is coating-free printing, requiring the use of coating-free UV ink; the other one is printing with pre-coating, requiring the use of eco-solvent inks. The main difference between them is the ink type.
UV ink has a strong corrosive, which plays a similar role with coating. It makes slight corrosion on the surface of printing material, which makes ink with better adhesion. Solvent ink without corrosive must use pre-coating to improve the adhesion of ink.
Besides, for printing of UV flatbed digital printing equipment which apply UV ink, some will require pre-coating,too, such as metal, ceramics, glass and other relatively smooth products printing, which require coating to enhance its adhesion.
Coating is a clear liquid, combined with additives, according to 70: 1 or 70: 2 to make the mixture. Then users can use a compressor and 3~5 spray guns to spray the coating to the surface of the products. It is better to place for a few minutes after spraying, which will offer better printing output. Remember, the operating environment should be kept clean without dust to avoid dust on coating surface.
In addition, the sprayed coating products do not be placed for a long time. It’s better to run out within five days.