First of all, look at the appearance of the paper. The thermal paper of good quality has uniform color development, good smoothness, high whiteness and a little greenish. If the paper is very white, then the protective coating and thermal coating of the paper are not reasonable, too much phosphor has been added, if the paper is not smooth or looks uneven, then the paper coating is uneven, if the paper looks reflective The light is very strong, and too much phosphor is added.
Secondly, use fire to heat the back of the paper. If the color on the paper is brown, it means that the thermal formula is not reasonable, and the storage time may be relatively short. If the black part of the paper has small stripes or color blocks Uneven, indicating that the coating is uneven. The better quality paper should be dark green after heating, and the color blocks are uniform, and the color gradually fades from the center to the periphery.