PU paint, as well as other paints, requires executers to understand the process and the rate of mixing paint to ensure the beautiful colors, smoothness and gloss level. However, not any painter can do this well. Therefore, there is graining phenomenon in some works painted by PU paint after a time of use. This is the phenomenon of small bubbles rising from the painting surface, making the surface grainy and reducing the aesthetics of products.
The phenomenon is caused by too thick isocyanate density of subdivision causing the created CO2 could not escape out of the surface then creating the graining phenomenon.
To overcome this phenomenon, we need to reduce the isocyanate density of subdivision by:
• Reduce the rate of hardener
• Or increase the rate of solvent
• Or increase time between sprays (this measure is often the most effective).