In the coating industry, hiding power is a key indicator of how well a paint layer covers the substrate and how efficiently it is used. A coating with high hiding power saves raw materials, ensures a smooth surface, and enhances color uniformity. Among all technical factors, the particle size of pigments plays a decisive role. The more suitable the pigment size, the stronger the light scattering, helping the paint achieve maximum coverage and lasting color stability.
LIGHT SCATTERING MECHANISM IN THE PAINT FILM
Hiding power originates from the light scattering phenomenon occurring when light passes through the paint film. Pigment particles reflect and refract light, effectively blocking the substrate underneath. The scattering intensity depends on the difference in refractive indices between the pigment and the surrounding binder. The greater the difference, the stronger the scattering and the higher the hiding power.
Among all pigments, titanium dioxide (TiO₂) exhibits the highest refractive index—around 2.7—making it the most effective pigment for opacity. However, this property only performs at its peak when the particle size lies within the optimal range of 0.2–0.3 microns. At this size, visible light is scattered most effectively, resulting in a bright, white coating with excellent coverage and visual uniformity.
THE INFLUENCE OF PARTICLE SIZE
When the pigment particle size exceeds 1 micron, its ability to scatter light drops significantly. Light can penetrate the paint film instead of reflecting, leading to poor hiding and uneven surfaces. Larger particles may also settle or agglomerate, reducing system stability and surface smoothness.
Conversely, particles smaller than 0.1 micron behave more like dyes. Light passes through instead of scattering, making the film appear more transparent and reducing opacity. Although gloss may increase, hiding power decreases notably. Therefore, controlling particle size within the optimal range is essential to maintain scattering efficiency and consistent performance.
PARTICLE SIZE CONTROL IN PAINT MANUFACTURING
Particle size is mainly determined by the grinding and dispersion stages. These are crucial steps in paint production that break down pigment clusters and produce fine, uniform particles. If grinding is insufficient, large particles remain, reducing hiding power. On the other hand, excessive grinding produces overly fine particles that weaken light scattering. Therefore, adjusting grinding speed, time, and media size must be carefully calculated.
Dispersing agents play a vital role in stabilizing particle size within the paint system. They prevent agglomeration, ensuring even distribution and maintaining optimal light reflection. When grinding and dispersion work in harmony, the coating achieves a smooth surface, high hiding power, and superior long-term stability.
PRACTICAL APPLICATIONS IN DIFFERENT PAINT SYSTEMS
In water-based paints, pigments with optimal particle size enhance whiteness, smoothness, and hiding efficiency. High performance can be achieved even with lower pigment loading, reducing production costs. In contrast, oil-based or decorative paints sometimes use slightly larger particles to increase gloss and create special light effects. For industrial and automotive coatings, the goal is to achieve both high opacity and strong reflectivity. Pigment size is tightly controlled to ensure color durability, brightness, and visual depth. Some formulations combine TiO₂ with iron oxides to boost light absorption and contrast, producing coatings with vivid and stable colors.
Typical TiO₂ grades such as CR-1120, R-2160, R-902, and R-750 are optimized within the ideal size range. These products are suitable for various paint systems—from decorative to industrial coatings—offering excellent opacity and consistent scattering performance.
Explore Vichem’s officially distributed TiO₂ products below
VICHEM – AUTHORIZED DISTRIBUTOR OF CERTIFIED CHEMICAL ADDITIVES IN VIETNAM
Vichem is the official distributor of Zealan pigments in Vietnam. We not only provide quality products but also provide after-sales services that meet international standards. Services include:
- Technical consulting: Our specialists help clients select suitable materials for specific applications.
- Color-matching tests: Vichem’s technical team conducts matching trials to ensure design precision and color consistency.
- Application support: We assist customers during production to ensure maximum efficiency and coating performance.
For more information about our products, please contact us via:
📞 Hotline: 08 1790 1790
📧 Email: contact@vichem.vn
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