Aluminum pastes

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Aluminum pastes, a kind of metallic pigments, is formed by a great amount of tiny aluminum flakes. It is often used in dope, printing ink, and plastics. When used with other paints, special effect may appear. The particle diameter of aluminum pastes is larger than that of color pigments. While the particle size of color pigments is in the wavelength range of visible light, the flake diameter of special effect pigments is generally around 5-45μm.

Particle size

Particle size is one of the most important standards to differentiate varied aluminum pastes. Among the same series product, more coarse the particle diameter much more bright and white; more narrow the particle size, more excellent the coverage and looks very fine through visible lights though looks not so bright. D50, that’s medium particle size, is often used to label the particle size and its unit is μm that’s one thousand percent of millimeter.

Particle size distribution

The granules of the aluminum flakes are very title so it is impossible that's every granule has the same size. The proportion of granules in different size is called particle size distribution. Particle size distribution thus has important effect on the optical properties of metallic pigments. More narrow the particle size distribution, more equal the size of the granules and more excellent the optical properties.

Whiteness & brightness

The metallic effect of e.g. car finishes is achieved by the reflection and scattering of light on the flakes, which are better or worse orientated in the film.         The visual impression created depends on the ratio between reflected and scattered light. The proportion of scattered light increases with the number of edges scattering the light.         The coarser the pigment, the rounder the shape of the particles, the higher the proportion of reflected light and thus of the brilliance, brightness and color saturation.