The recommended dispersion technique included the addition of sufficient co-solvent or vehicle co-solvent blend to the paste to develop a thick, creamy consistency under slow-speed mixing. After the development of a smooth, lump-free pigment slurry, total letdown can be completed with additional co-solvent and/or vehicle co-solvent blend. This grade, as supplied, is a paste and needs no additional mechanical shear to develop the aesthetic properties of the individual flakes. The only requirements for incorporation and dispersion into the vehicle are viscosity reduction, to overcome the cohesive nature of the paste, and minimum mechanical agitation to assure uniform incorporation throughout the vehicle. Excessive mechanical shear may damage the flake, thereby compromising gassing stability and changing its aesthetic value.
Limitations: This grade has been chemically treated to inhibit the aluminum-water reaction. However, under certain conditions, this reaction can still take place. The conditions which can affect this reaction are extremes in pH, excessive mechanical shear, and the chemical aggressiveness of the resin and additives. Because this reaction is a complex mechanism involving, perhaps, many of a coating’s constituents, Silberline recommends that coatings manufacturers evaluate this grade of aluminum pigment in their system to determine its own unique appearance and stability characteristics.
Caution: The use of high speed mixing equipment, such as Cowles dispersers, may distort the aluminum flake, resulting in poor appearance.