42 PAINTING MATERIALS

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Oils, history in painting (see also Resins, history in painting). A great amount
has been written on this subject but many problems still remain obscure, and many
questions are still unanswered. For poverty of evidence to the contrary, oil
painting is considered to belong to relatively modern times. Oil has^ never played
an extensive role in Oriental art, but, before it can be eliminated entirely from the
ancient art of the East, further study must be undertaken. ^
Whenever the early classical writers on history or medicine speak of oils, it is
always with reference to their medicinal, cosmetic, or culinary uses. Dioscorides,
who is supposed to have lived in the age of Augustus, mentions two drying oils,
walnut oil and poppy oil; the use of bruised linseed is recommended medicinally
by Hippocrates and other Greek writers on medicine; the medicinal oils enumer-
ated by Pliny include walnut oil; he also speaks of the juice of linseed; Galen,
writing in the II century, speaks of the drying properties of linseed and hempseed
oils and he also mentions specifically the expression of walnut oil. The first mention
of a drying oil in connection with works of art is by Aetius, a medical writer of the
V and the beginning of the VI century. He describes the preparation of walnut oil
and says that it is used by gilders and encaustic painters to preserve their work
owing to its property of drying. He mentions linseed oil on the same page in con-
nection with its medicinal uses, yet he speaks of nut oil as though it were the only
one employed in the arts. Leonardo, writing a thousand years after Aetius, recom-
mends nut oil, thickened in the sun, as a varnish,
The first descriptions of the preparation of an oil varnish, by dissolving resins
in a drying oil, are found in the Lucca MS., supposed to be of the VIII century,
and in the Mappae Clamcula^ of doubtful though early date (see Berger and
Merrifield). It is not until the time of Theophilus, XII century, and of the MS.
of Eraclius, supposed to be of about the same date, that the use of a drying oil as
a paint medium is described. The earliest writers who distinctly mention the
admixture of solid colors with oil for the purpose of painting are thus Eraclius,
Theophilus, Peter de St Audemar, and the unknown author of a similar treatise
preserved in the British Museum (see Merrifield). It has been supposed that both
Eraclius and Theophilus were of some country north of the Alps, but there is
ample evidence that oil painting of a limited kind was practiced in Italy at an early
period. Lorenzo Ghiberti says that Giotto occasionally painted in oil. Again, accord-
ing to a document found by Vernazza in the archives of Turin, a Florentine painter,
named Giorgio d'Aquila, contemporary with Giotto, was employed in 1325, by
the Duke of Savoy, to paint a chapel at Pinarolo. The artist was furnished with a
large quantity of nut oil for the purpose, but the oil, from some cause or other, did
not answer his purpose, and was sent to the ducal kitchen (Eastlake, I, 46).
In England early documents relate to the use of oil in art. By 1239 it is mentioned