Some inks which are manufactured using metal pigments, iridescent pearl effect pigments, or interference pigments, have a great reputation among all the printing inks. These are even commonly called gold and silver printing inks, or to be precise; inks having metal-like luster and brilliance.
A varying proportion of copper and zinc in ground brass alloys yield Gold Bronze pigments. The redness of gold bronze depends upon the quantity proportion of copper in the alloy; the amount of copper is directly related to the redness. The particles size of the metal pigments has the ability to adapt to respective printing technology because of the technology that is used in manufacturing of Bronze.
The particle size is 3.5 micrometers for offset printing, 8 to 9 micrometer for gravure and flexographic printing. Therefore, the thickness of ink’s film is larger than the conventional inks/pigments i.e. 0.1-3 micrometers.
Aluminum of 99.5% purity is assumed for manufacturing the silver pigments. When the melting is done in the induction furnaces, the metal turns into molten liquid state. A compressed air steam then lacerates the molten liquid metal. A metal granulate with the finish of a polished metal surface gets yielded as the end product. These inks take the same time to dry as usual inks that too by the process of absorption and oxidation.
Modern developments in this field are Gold and Silver printing inks which are built-upon water dilatable dispersion varnishes, a chambered blade system then transfers the ink to coating units. The drying of these inks is done by two processes that are absorption into the surface and evaporation of the water possessed by these inks. The advantage is more brilliance of these inks than the normal gold and silver inks, which use the old vanish based technology.
The pearlescent inks have a unique characteristic gloss in printed images in comparison to iridescent gloss of pearls. Encased by many metal oxide layers, these pigments have a mica core. Printing inks made using metal pigments are also used for flexographic and gravure printing. There are similarities in the structure of these pigments and organic or inorganic pigments of color.
Satin inks are nothing but Silver-metallic printing inks mixed with colored inks in any proportion.