This specification covers raw and burnt umber pigments. The pigments could be in a dry or paste in oil form. Dry pigments should conform to the composition requirements for iron oxide content, calcium compound content, moisture and other volatile matter content, coarse particle content, and organic color content. Raw umber dry pigments should be in a soft, dry form and made from a hydrated iron oxide permeating a siliceous base and free of admixtures. Burnt umber dry pigments should be produced by raw amber calcination and free of admixtures. Paste in oil pigments should conform to the specified pigment content, nonvolatile vehicle content, moisture by distillation content, and coarse particle and skin content. Both raw and burnt umber paste in oil pigments should be made by thoroughly grinding the pigment with linseed oil with a small amount of wetting or dispersing agents.

1.1 This specification covers the pigments commercially known as raw umber and burnt umber.

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