Because the surface of coated paper is smooth and has poor ink absorption ability, it is difficult to prevent ink from running off when exposed to water. However, it is not completely unusable, but you should pay attention to the following points: first, the ink should not be too thick, which is not conducive to the absorption of coated paper, and if the ink is too thick, it will definitely be more likely to run away when exposed to water; second, try to choose fresh ink Good quality, because the glue in inferior ink is of poor quality, easily deteriorates, and cannot have a fixing effect (do not use permanent ink, because most of the permanent ink is oxidized and degummed more easily); third, put it on the coated paper after writing it. Let it dry for a while in a hard-to-reach place to allow the ink on the surface to stabilize and solidify. In addition, we can also mix a little bit of gum water and spray a layer on the completely dry work, which can also have a certain protective effect. Be careful not to be impatient when spraying. Use a very fine mist for the first spray, and then spray it a second time after it is completely dry. Spray several more times until it is fully covered. Be careful not to spray too much at one time and it will cause stains.