15. Pigment precipitation:

Phenomenon: The color becomes lighter or discolored, resulting in a paste version.
the reason:
(1) The pigment has poor affinity with the medium and coagulates together after being dispersed.
(2) Insufficient dispersion.
(3) The viscosity is too low and the stirring is insufficient.
Approach:
(1) Add anti-precipitation agent when making ink.
(2) Full dispersion and rolling.
(3) Select affinity pigments and media.
(4) Stir thoroughly while using.