| Résumé : |
So far we have covered the formulating principles of interior emulsion paints. Now let us turn our attention to exterior emulsion paints. The formulations of exterior paints differ from interior one as the former had to take on and withstand the beating of weather conditions in addition to exhibiting of non-fading characteristics. We all know that, Paint typically contains four essential ingredients, namely pigment, binder, liquid and additives. Any or all of these ingredients may be a single component or may comprise multiple items. Pigment provides colour to paint and also makes paint opaque, and pigment is usually of mineral or organic origin although some pigments are artificially produced. Some pigments possess Iittle or no bulk and must be fixed on a more solid, but at the same time transparent, substance or base. "Prime" pigments provide colour and opacity (opaque coverage). The most common prime pigment is titanium dioxide, which is white and is used in latex and water-based paints. Traditionally, pigments have also added hiding properties to paint. Specialty or extender pigments may also be used and provide bulk to the paint at a low cost. The extender pigments are often chosen for their impact on properties like scrub resistance, stain resistance and chalk resistance. China Clay is frequently used for this purpose. These pigments are added to the paint to provide certain characteristics such as thickness, a certain level of gloss and durability. They are usually naturally occurring products which originally were in the earth and were mined and purified for use in paint. Such pigments as calcium carbonate, talc and clay are, for example, used extensively in paints. |
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Formulation principles of exterior emulsion paints in PAINTINDIA, Vol. LXVIII, N° 3 (03/2018)
