1.1 This specification covers the pigments commercially known as synthetic pure brown iron oxides and blends. These pigments are suitable for use in paints and coatings. Methods of manufacture are:
1.1.1 Precipitation of iron salts.
1.1.2 Calcination of precipitated iron oxides.
1.1.3 Blends of synthetic red, yellow, and black iron oxides.
1.1.4 Blends of synthetic red, yellow, and black iron oxides plus the addition of carbon black to a maximum of 5.08201;%. Small amounts of carbon black are added to obtain tinting colors not obtainable when synthetic brown iron oxide or carbon black are used singly.