This specification establishes the properties and requirements for the pigments commercially known as synthetic pure brown iron oxides and its blends, suitable for use in paints and coatings. The pigment, which shall be soft, dry, and finely pulverized, may be manufactured by either of the following methods: precipitation of iron salts; calcination of precipitated iron oxides; blends of synthetic red, yellow, and black iron oxides; and blends of synthetic red, yellow, and black iron oxides plus the addition of carbon black. Specimens shall be suitably sampled and tested, and shall adhere to specified requirements as to total iron oxide, ferrous iron, carbon black, moisture and other volatile matter, organic coloring matter, total sulfates, coarse particles (total residue retained on No. 325 sieve), and water-soluble matter.

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 5.0 %. Small amounts of carbon black are added to obtain tinting colors not obtainable when synthetic brown iron oxide or carbon black are used singly.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.