Uneven coloring of PU color paste may be caused by many reasons. The following are some possible factors:
Uneven color paste formula: If the proportions of various pigments, solvents and additives are incorrect or unevenly mixed when mixing color pastes, uneven coloring will result.
Under- or over-stirring: Stirring is a critical step in uniformly mixing pigments, solvents, and additives. Insufficient or over-stirring may result in uneven coloring of the paste.
Color paste precipitation: If certain components in the color paste precipitate, it will lead to uneven distribution of pigments, which will affect the coloring effect.
Uneven base material: If the surface of the base material is uneven or has uneven water absorption, it will cause the color paste to be unevenly distributed on the surface, affecting the coloring effect.
Coating process problems: During the coating process, incorrect settings such as spray pressure, nozzle adjustment, coating speed and other parameters may lead to uneven coloring.
Environmental factors: Environmental factors such as temperature and humidity will also affect the fluidity and drying speed of the color paste, thereby affecting the coloring effect.
Equipment problems: If the coating equipment has faults or poor conditions, such as nozzle blockage, unstable coating pressure, etc., it will also lead to uneven coloring.
