First of all, it is the most important and easy to be ignored by us. Many heat-sensitive cash register paper, especially those without brands, they add a lot of phosphor and calcium carbonate for the sense of paper, which makes the paper lose a lot of scraps in printing and cutting, seriously affecting the life of the printing head and the automatic paper cutter, which should be remembered. Appearance color: When purchasing heat-sensitive cash register paper, pay more attention to the appearance of the paper. From the color, we can distinguish the quality of the protective coating and the thermal sensitive coating to a certain extent. If the paper is very white, it indicates that the protective coating and thermal coating of the paper are unreasonable and excessive phosphor is added. If the paper turns green quietly, its quality will be better. If the paper looks smooth and flat, the coating of the thermal paper is more uniform. On the contrary, the uneven coating of the paper will seriously affect the printing effect. If the paper looks very reflective, but also the reason for adding too much phosphor, it is best not to choose such a thermal paper. Sunshine contrast: This method is very simple, just use the same fluorescent pen to smear different printed papers and put them in the sun (this can accelerate the reaction of thermal coatings to light). The longer the time needed for blackening, the longer the time needed for the preservation of the thermal paper. Roasting: In fact, the principle of distinguishing the method of roasting from the sunshine is similar. We can use a lighter to gradually heat the paper in discord. The color of the paper will change with the heating. If the color of the end is brown, it means that the heat-sensitive formula is not reasonable and the storage time can be shorter. If there are thin stripes or loose color blocks on the cash register paper, the coating is not uniform. On the contrary, the better quality thermal paper will show black-green (with a little green) at the end of heating. The color block is uniform, and the color gradually fades from the center of heating to the adjacent area.