When UV inkjet printing onto smooth media like glass and metal, a layer of coating on the surface is necessary so the adsorption of ink to the printing material can be strengthened, and the printing quality as well as sharpness will be optimized. However, sometimes the print images are still vague even the coating has already been painted. And why this happens?

One possible factor is the ink absorption performance of the coating itself is poor. This leads to the ink fails to penetrate into the interior coating and the images are dim and not clear. About this, Yueda Printing Technology(YOTTA) advises users to buy the coatings which recommended by manufacturers, since those coatings have undergone many tests and feedbacks.

If the problem doesn't lie in the coating's quality, then we should consider the mismatch between the ink and the coating. Usually one certain kind of coating matches one material, if we don't consider the "match" thing, the adhesion of ink would decrease. The print coatings are also varied with different ink type, if we discriminately use them, the ink will dissolve into the coatings.

Sometimes we also need to check whether the coating is slightly damp or excessively dry. If the UV inkjet printer starts its working when the coating is still slightly damp, the ink will spread into the coating and the images are vague.

Furthermore, the working environment is also an important premise. Too much humidity affects the dryness of coatings and the sharpness of images be weakened. This usually happens in the rainy days.

If all the factors mentioned above are excluded, contacting technicians to solve this is the best thing to do. Because the ink types of different manufacturer are not the same, and the coating configuration involves complicated chemical knowledge. It is also a mirror of the technical level of manufacturers.