9. Pan-copper light
The copper film on the surface of the film shows a purple color, and it suddenly glows in the sunlight.
the reason:
(1) Affected by sunlight, ultraviolet rays or affected by high temperature;
(2) Caused by the migration of red, blue, etc. pigments, especially when the pigment particles are less than 0.1 μm.
Prevention:
Use inks with good weather resistance and use suitable pigments for color matching.