Insufficient coverage
The color paste not only gives the latex paint rich colors, but also has an important function to provide the hiding power of the latex paint. When matching dark paint, people tend to pay attention to color, but ignore the hiding power of latex paint. Therefore, quality problems in this area often occur, especially when matching red or yellow dark paint.
Since the current national standards for latex paints only stipulate the contrast ratio of white or light-colored latex paints, there are no specific indicators for hiding power for intermediate-color and dark-colored latex paints. Therefore, many manufacturers have no control over the hiding power of intermediate and dark latex paints. Intermediate color and dark latex paints contain less titanium dioxide and more organic pigments, but the hiding power of organic pigments is poor, so intermediate color and dark latex paints are most likely to have insufficient covering power. Some manufacturers even ask their users to apply two coats of light color, three coats of medium color, and four coats of dark color. Obviously, this requirement is difficult for users to accept. The ways to solve the problem are:
① The titanium dioxide content of the base paint should be appropriate, and the base paint with high, medium and low titanium dioxide content should be used respectively for light, medium and dark color toning. Titanium dioxide can provide good hiding power of the paint . If the amount of titanium dioxide is too small, it is difficult for the paint to have good hiding power.
②Usually the hiding power of inorganic pigments is much better than that of organic pigments. Therefore, when making color formulas, inorganic pigments should be used as much as possible, or inorganic pigments and organic pigments should be used together for color matching.
③ When selecting organic pigments, not only are the pigments required to have good weather resistance and tinting strength, but also they are required to have good hiding power.
Excess hiding power
Another common problem is excess coverage. Many small and medium-sized paint factories in CHINA are accustomed to producing white latex paint, and rarely or even not produce translucent latex paint and latex varnish. They often use white latex paint to match dark, medium and light-colored latex paints, or use translucent paint to match dark latex paints, and white paint to mid-color latex paints. In this way, a large amount of color paste must be added to achieve a certain degree of saturation. The result is:
①White paint already has good hiding power, but after adding a large amount of color paste, the hiding power is seriously excessive.
②The addition of a large amount of color paste will double the cost of color matching.
③When the color paste exceeds the maximum amount, it will seriously affect the water resistance, scrub resistance and weather resistance of the latex paint.
Modern color matching systems usually use 3 different titanium self-powders according to the depth of the color.
content of the base paint to tint. At the same time, choose pigments with good hiding power, fully consider the principle of choosing inorganic pigments as much as possible, and design each formula, which can effectively avoid the occurrence of excessive hiding power.
The hiding power of latex paint is also related to the thickness of the coating film. The color formula is generally designed according to the coating with a dry film thickness of 30~60μm. When the dry film thickness is greater than 60µm, such as elastic latex paint, the coloring formula should be adjusted to properly reduce the hiding power of the paint. Users who use the color matching system can easily adjust the color paste distribution and injection rules in the color management software to practice all color adjustments.
