Coloured natural iron oxides are earth pigments having outstanding characteristic, such as their stability under practically all conditions encountered in commercial applications. These pigments are unaffected chemically or physically by acids, alkalis, sunlight or moisture. They possess excellent hiding power, light fastness, reasonable tinting strength. They do not bleed or fade, are easily wetted and dispersed (Rammelt and Reinhardt, 1994; Morgan, 1990;Patton, 1973), opaque to UV light which provides good protection of paint binders (Rammelt and Reinhardt, 1994; Morgan, 1990), and can provide hard impervious films that resist outdoor weathering and superior protection at a relatively low cost. Protection mechanism of iron oxides to metal substrates is physical rather than chemical, i.e. by mechanically strengthening the paint film, reducing moisture permeation through the film, and by screening out destructive UV radiation (Payne, 1973). Alumina has no role in preventing steel from corrosion, but they possess the flaky structure that may help in corrosion prevention when assisted by another anticorrosive pigment (Svoboda and Mleziva, 1984). Combining these two pigments and calcining them together, a new pigment having different properties than that of its counterparts could be formed.
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