Sieve paint precisely
Finest sieving of dry paints in powder form
Pigments, paint and colorants are chromophore substances in powder form. Pigments are insoluble in the carrier medium, colorants are soluble. The carrier medium is the substance in which the pigment is embedded, normally varnish or plastics. Colorants and pigments can be organic or inorganic, achromatic or colored.
Sieving of paint and pigments
Relevant for the characteristics of pigments are attributes like crystal structure, crystal modification, particle size and particle size distribution. Pigments are used in varnish, dispersion paints and printing inks, as coating pigment resp. white pigment and filler in paper production, to color plastics, in colors for artists and in crayons, for printing on textiles and special applications like cosmetics. Important inorganic pigments are haematite (red ferric oxide), colored clay (red ochre), ochre (yellow ferric oxide) and manganese dioxide. One of the colors used since the early beginnings is white and the white pigment known for the longest time is calcium oxide (CaO) which is gained from burned lime stone. Pigments are able to adhere to aggregates. In case that these aggregates are connected at their corners or edges they are defined as agglomerates. These undesired agglomerates are separated by screening. Pigments can be used pure or with fillers e.g. as powder coating.
Natural and synthetic pigments
Inorganic pigments are differentiated into natural and synthetic pigments. Natural pigments are earths and minerals (earth tones and mineral white). Before use they only have to be processed mechanically, mostly drying, screening and milling. Synthetic pigments are inorganic substances like pigments giving a metallic effect, carbon black, white pigment or ferric oxide pigments. The most important pigments can be differentiated into chemical families: titanium dioxide, carbon black, bismuthinite, oxides and hydroxides, ultramarine, cadmium and chromate pigments. Oxides and hydroxides can be further classified into ferric oxide pigments, chromium oxide and mixed phase oxide pigments. Chromate pigments are further divided into chrome yellow, chrome green and Molybdate. Because of its fine particle size and its respective characteristics carbon black often is regarded as organic pigment.
Due to their widespread use in industry white pigments have an exceptional position under which white minerals containing calcium carbonate are the most important. Because of its refractory index in production of varnish calcium carbonate is mainly used not as pigment but as filler. The appearance of a metal pigment is mainly determined by its particle size and the regularity of particle shape. Coarse particles give a sparkling effect while fine particles create a so called “flop” which means a smooth changeover when changing the viewing angle. Respective to this particles of a metal pigment have to be separated by size before they are embedded into the varnish.