Application of aluminum-silver paste in the coatings industry
Release time:
2026-02-05
To achieve excellent performance—such as superior gloss, shimmering effect, brightness, opacity, tinting strength, angular color shift effect, vividness, and floatability—in aluminum powder-containing pigment-based coatings, thorough dispersion is essential. However, when dispersing these pigments, please pay attention to the following tips and recommendations.
1. Dispersion of aluminum silver paste
To achieve excellent performance—such as superior gloss, shimmering effect, brightness, opacity, tinting strength, angular color shift effect, vividness, and floatability—in aluminum-powder-containing pigment-based coatings, thorough dispersion is essential. However, when dispersing these pigments, please pay attention to the following tips and recommendations.
Tip: Aluminum flakes are prone to bending and breaking. During paint production, if subjected to high-speed stirring or other continuous, vigorous processing, their geometric structure can easily be compromised, leading to undesirable phenomena such as coarse particles, dull color, reduced opacity, and metal migration. Therefore, dispersion methods involving high shear forces should be avoided.
Recommendation: It is recommended to adopt a pre-dispersed approach: First, select an appropriate solvent or a mixture of several solvents. Add the solvent to the aluminum powder slurry at a ratio of 1:1 or 1:2 (solvent to slurry), and stir slowly until uniform (approximately 10–20 minutes). Then, add a wetting agent or dispersant to the system.
2. Resin System
Many commonly used coating bases—such as oil-based varnishes, acrylics, alkyds, epoxies, polyurethanes, and waterborne bases—can both accommodate floating and non-floating aluminum silver paste pigments. Generally speaking, any coating base or solvent that is compatible with the solvent in the aluminum silver paste and does not chemically degrade the paste itself is suitable. It’s worth noting that aluminum is an amphoteric metal; therefore, the acid value of the coating should be kept below 7.
Solvent Selection
The choice of solvent is primarily determined by the paint formulation. For non-flotation aluminum silver paste, polar solvents such as aliphatic or aromatic hydrocarbons, esters (e.g., butyl acetate), ketones (e.g., methyl ethyl ketone, methyl isobutyl ketone), and alcohols (e.g., ethanol) can be widely used. However, for flotation aluminum silver paste, only non-polar solvents should be employed—preferably aliphatic or aromatic solvents with high surface tension, especially petroleum solvents, diphenyl, toluene, and high-flash-point naphtha, as these solvents promote excellent floating performance. Moisture can react with aluminum to produce hydrogen gas, leading to a bloating effect; therefore, the moisture content in coatings must be strictly controlled below 0.15%. It is recommended to use Bayer’s dehydrating agent OF to remove excess moisture from coatings, solvents, or diluents. Water-containing solvents are unsuitable for use with any type of aluminum silver paste pigment.
Selection of aluminum-silver paste
The particle size and particle-size distribution of aluminum silver paste pigments have a critical impact on color, opacity, angular-dependent color shift, and gloss. Therefore, particle-size distribution is an important parameter that cannot be overlooked when selecting aluminum silver paste. When choosing an aluminum silver paste, it is essential to opt for products with stable particle size and particle-size distribution. It’s worth noting that particle size and particle-size distribution are not the only technical parameters to consider when selecting aluminum silver paste. Even if two aluminum silver pastes have identical particle sizes and particle-size distributions, differences in surface treatment or variations in the shape of the aluminum flakes can still lead to disparities in optical effects such as hue, chroma, metallic appearance, whiteness, and angular-dependent color shift. Consequently, to determine precisely which aluminum silver paste pigment is most suitable, it is necessary to conduct small-scale sample testing and compare the results against reference samples.
