Oxide of Iron Red in Oil as found in some color grinders' lists is usually a mixture of native red oxide, or it may be a copperas red, containing any where from 70 to 90 per cent sesquioxide of iron in the native red, with a gangue of silica and alumina, as occurs in nature with the oxide, while the red oxide made in the furnace from green copperas may run about 60 to 70 per cent in oxide, the inert material consisting of dead burned sulphate of lime. These reds are usually of medium or dark shades, and will require the same proportion of pigment and oil for mixing and grinding as the best grades of Venetian red noted above, that is, about 77 pounds of dry pigment and 23 pounds raw linseed oil. In native reds the Spanish and Persian Gulf reds are excellent types and are lower in price than the copperas reds of similar percentages, though the latter are usually much richer in color.

Maroon Oxide in Oil, when so branded, may be a deep Indian red, or it may be Persian Gulf red.