1. Appearance: If the paper is very white, indicating that the paper protective coating and thermal coating is unreasonable, adding too much phosphor, the better paper should be slightly green. Paper fineness is not high or looks uneven, indicating that the paper coating is not uniform, if the paper looks very strong reflection, but also added too much phosphor, the quality is not good.
2. Fire-baking: The method of fire-baking is also very simple, heating with a lighter on the back of the paper, if heated, the paper appears brown, indicating that the heat-sensitive formula is not reasonable, storage time may be shorter, if the black part of the paper has small stripes or color block is not uniform, indicating that the coating is not uniform. The better quality paper should be dark green (with a little green) after heating, and the color patches are uniform, and the color gradually fades from the center to the surrounding.
3. Sunlight contrast identification: the printed paper with a fluorescent pen coated in the sun after drying (this can speed up the thermal coating reaction to light), which kind of paper the fastest blackening, indicating that the shorter the time to preserve.