The green color is recommended! The effect of a violet pen is purple or blue, the effect is weak, it is best to use at night! Violet pen irradiated on the surface of the paper is easy to turn blue is mainly due to the light scattering and absorption properties, when irradiated on the surface of the paper, the light will be scattered phenomenon, different wavelengths of light in the scattering of different performance! When first used, too low a temperature may cause the product not to work, if this happens, you can first leave it at room temperature for some time.
