PAINTING MATERIALS
important, being used extensively as an anti-corrosive pigment for iron, and
familiar in the priming coats used for structural steel and for iron fences.
Red Ochre (see also Iron Oxide Red) is an earthy variety of iron oxide which
contains more or less clay and silica and is one of the most important of the natural
pigments. The best contains as high as 95 per cent of ferric oxide. It has been
widely used. It was the red paint of the American Indian and the sinopis or
sinopia of classical antiquity (see Thompson, The Materials of Medieval Painting,
p. 98).
Riiodamine (Rhodamine toner) is one of the stable, synthetic, organic dye-
stuffs used for making red lake pigments. Rhodamine 6G, discovered by Bernthsen
in 1892, is the ethyl ester of diethyldiamino-0-carboxy-phenyl-xanthenyl
chloride, C26H26N203C1 (ColourIndex, p. 190).
Rinnman's Green (see Cobalt Green).
Safflower (carthame) is a natural organic red coloring matter which is pre-
pared from the dried petals of the Dyer's Thistle, Carthamus tinctorius, which is
cultivated in the East, in Egypt, and in southern Europe. The red coloring matter
is carthamin, or carthaminic acid, C25H240i2. This is extracted by steeping the dry
petals in cold dilute sodium carbonate solution. Safflower extract is only slightly
soluble in water and alcohol. The dye is an orange solution with alkalis and is
turned dull red by dilute sulphuric acid. It was once used widely in the East as a
dye and for the manufacture of pigments and cosmetics.
Saffron is the golden yellow coloring matter that is extracted from the dried
stigmas of the crocus flower, particularly Crocus sativus. It has long been a flavor-
ing for food and was formerly used in painting, especially, for illuminating and
embellishing the pages of books. The color was put directly into a medium without
a mordant. Jehan le Begue (Merrifield, 1,128) and other writers of his period speak
of adding it to green, particularly copper green, to make a warmer tone. Saffron
is mentioned by Theophilus (p. 41) and by Le Begue (op. «/., p. 158) for auri-
petrum, a transparent yellow coating over tin foil to make it look like gold. Beck-
man has given a whole chapter to saffron (I, 175-180), and believes it originally
was brought from the Levant into Spain and Europe by the Arabs.
Sap Green is a natural organic dyestuff derived from the ripened berries of
several varieties of the buckthorn, Rhamnus. The juice of the berries may be used
directly or may be precipitated with alum. In early times it was not dried but was
sold in bladders as a dense syrup (Thompson, The Materials of Medieval Painting,
pp. 169-171). Although a most fugitive substance, it is still used in water color.
On the old illuminated manuscripts, it has often survived because of ideal condi-
tions. Oil paints now sold under this name usually contain coal tar lakes.
Scheele's Green, an acid copper arsenite, CuHAsOa, was the first artificial
green pigment in which copper and arsenic were the essential constituents. It
was first prepared by the eminent Swedish chemist, Carl Wilhelm Scheele, in 1778.
Methods of preparation varied in details, but it was usually made by dissolving