Oil paint is a type of slow-drying paint that consists of particles of pigment
suspended in a drying oil, commonly linseed oil. The viscosity of the paint
may be modified by the addition of a solvent such as turpentine or white
spirit, and varnish may be added to increase the glossiness of the dried oil
paint film. Oil paints have been used in Europe since the 12th century for simple
decoration, but were not widely adopted as an artistic medium until the early
15th century. Common modern applications of oil paint are in finishing and
protection of wood in buildings and exposed metal structures such as ships
and bridges. Its hard-wearing properties and luminous colors make it desirable
for both interior and exterior use on wood and metal. Due to its slow-drying
properties, it has recently been used in paint-on-glass animation. Thickness of
coat has considerable bearing on time required for drying: thin coats of oil
paint dry relatively quickly. History
The technical history of the introduction and development of oil
paint, and the date of introduction of various additives is still—despite
intense research since the mid 18th century—not well understood. The
literature abounds with incorrect theories and information: in general,
anything published before 1952 is suspect. Till 1991 nothing was known on
the organic part of parietal paintings from the Paleolithic time. Many
assumptions were made about the chemistry of the binders.
= First recorded use= The oldest known oil paintings date from
650 AD, found in 2008 in caves in Afghanistan's Bamiyan Valley, "using
walnut and poppy seed oils." = Classical and medieval period=
Though the ancient Mediterranean civilizations of Greece, Rome, and Egypt
used vegetable oils, there is little evidence to indicate their use as media
in painting. Indeed, linseed oil was not used as a medium because of its tendency
to dry very slowly, darken, and crack, unlike mastic and wax.
Greek writers such as Aetius Amidenus recorded recipes involving the use of
oils for drying, such as walnut, poppy, hempseed, pine nut, castor, and linseed.
When thickened, the oils became resinous and could be used as varnish to seal and
protect paintings from water. Additionally, when yellow pigment was
added to oil, it could be spread over tin foil as a less expensive alternative
to gold leaf. Early Christian monks maintained these
records and used the techniques in their own artworks. Theophilus Presbyter, a
12th-century German monk, recommended linseed oil but advocated against the
use of olive oil due to its long drying time. Oil paint was mainly used as it is
today in house decoration, as a tough waterproof cover for exposed woodwork,
especially outdoors. In the 13th century, oil was used to
detail tempera paintings. In the 14th century, Cennino Cennini described a
painting technique utilizing tempera painting covered by light layers of oil.
The slow-drying properties of organic oils were commonly known to early
painters. However, the difficulty in acquiring and working the materials
meant that they were rarely used. = Renaissance onwards=
As public preference for naturalism increased, the quick-drying tempera
paints became insufficient to achieve the very detailed and precise effects
that oil could achieve. The Early Netherlandish painting of the 15th
century saw the rise of the panel painting purely in oils, or oil
painting, or works combing tempera and oil painting, and by the 16th century
easel painting in pure oils had become the norm, using much the same techniques
and materials found today. The claim by Vasari that Jan van Eyck "invented" oil
painting is not correct but has cast a long shadow, but van Eyck's use of oil
paint achieved novel results in terms of precise detail and mixing colours
wet-on-wet with a skill hardly equalled since. Van Eyck’s mixture may have
consisted of piled glass, calcined bones, and mineral pigments boiled in
linseed oil until they reached a viscous state—or he may have simply used
sun-thickened oils. He left no written documentation.
The Flemish-trained or influenced Antonello da Messina, who Vasari wrongly
credited with the introduction of oil paint to Italy, does seem to have
improved the formula by adding litharge, or lead oxide. The new mixture had a
honey-like consistency and better drying properties. This mixture was known as
oglio cotto—"cooked oil." Leonardo da Vinci later improved these techniques by
cooking the mixture at a very low temperature and adding 5 to 10% beeswax,
which prevented darkening of the paint. Giorgione, Titian, and Tintoretto each
may have altered this recipe for their own purposes.
The use of any cooked oils or Litharge darkens an oil painting rapidly. None of
the old Masters whose work survives used these in their paintings. Both
ingredients became popular in the 19th century. Since that time, experiments to
improve paint and coatings have been conducted with other oils. Modern oil
paints are created from bladderpod, ironweed, calendula and sandmat, plants
used to increase the resistance or to reduce the drying time.
= Paint tube= The paint tube was invented in 1841 by
portrait painter John Goffe Rand, superseding pig bladders and glass
syringes as the primary tool of paint transport. Artists, or their assistants,
previously ground each pigment by hand, carefully mixing the binding oil in the
proper proportions. Paints could now be produced in bulk and sold in tin tubes
with a cap. The cap could be screwed back on and the paints preserved for
future use, providing flexibility and efficiency to painting outdoors. The
manufactured paints had a balanced consistency that the artist could thin
with oil, turpentine, or other mediums. Paint in tubes also changed the way some
artists approached painting. The artist Pierre-Auguste Renoir said, “Without
tubes of paint, there would have been no Impressionism.” For the Impressionists,
tubed paints offered an easily accessible variety of colors for their
plein air palettes, motivating them to make spontaneous color choices. With
greater quantities of preserved paint, they were able to apply paint more
thickly. Carrier
= Characteristics= Traditional oil paints require an oil
that always hardens, forming a stable, impermeable film. Such oils are called
siccative, or drying, oils, and are characterized by high levels of
polyunsaturated fatty acids. One common measure of the siccative property of
oils is iodine number, the number of grams of iodine one hundred grams of oil
can absorb. Oils with an iodine number greater than 130 are considered drying,
those with an iodine number of 115-130 are semi-drying, and those with an
iodine number of less than 115 are non-drying. Linseed oil, the most
prevalent vehicle for artists' oil paints, is a drying oil.
When exposed to air, oils do not undergo the same evaporative process that water
does. Instead, they polymerize into a dry semisolid. This rate of process can
be very slow, depending on the oil. The advantage of the slow-drying quality
of oil paint is that an artist can develop a painting gradually. Earlier
media such as egg tempera dried quickly, which prevented the artist from making
changes or corrections. With oil-based paints, revising was comparatively easy.
The disadvantage is that a painting might take months or years to finish,
which might disappoint an anxious patron. Oil paints blend well with each
other, making subtle variations of color possible as well as creating many
details of light and shadow. Oil paints can be diluted with turpentine or other
thinning agents, which artists take advantage to paint in layers.
= Sources= The earliest and still most commonly
used vehicle is linseed oil, pressed from the seed of the flax plant. Modern
processes use heat or steam to produce refined varieties of oil with fewer
impurities, but many artists prefer cold-pressed oils. Other vegetable oils
such as Hemp, poppy seed, walnut, sunflower, safflower, and soybean oils
may be used as alternatives to linseed oil for a variety of reasons. For
example, safflower and poppy oils are paler than linseed oil and allow for
more vibrant whites straight from the tube.
= Extraction methods and processing= Once the oil is extracted, additives are
sometimes used to modify its chemical properties. In this way, the paint can
be made to dry more quickly, or to have varying levels of gloss, like Liquin.
Modern oils paints can, therefore, have complex chemical structures; for
example, affecting resistance to UV. By hand, the process involves first mixing
the paint pigment with the linseed oil to a crumbly mass on a glass or marble
slab. Then, a small amount at a time is ground between the slab and a glass
Muller. Pigment and oil are ground together 'with patience' until a smooth,
ultra-fine paste is achieved. This paste is then placed into jars or metal paint
tubes and labelled. Pigment
The color of oil paint derives from small particles of colored pigments
mixed with the carrier. Some of the earliest known pigments are charcoal,
iron oxide, and gypsum. Common pigment types include mineral
salts such as white oxides: zinc, titanium, and the red to yellow cadmium
pigments. Another class consists of earth types, e.g. sienna or umber. Still
another group of pigments comes from living organisms, such as madder root.
Synthetic pigments are also now available. Natural pigments have the
advantage of being well understood through centuries of use, but synthetics
have greatly increased the spectrum of available colors, and many are tested
well for their lightfastness. = Toxicity=
Many of the historical pigments were dangerous, and many pigments still in
popular use today are highly toxic. Some of the most poisonous pigments, such as
Paris green acetoarsenite) and orpiment, have fallen from use.
Many pigments still in use are toxic to some degree. Commonly used reds and
yellows are produced using cadmium, and vermilion red uses natural or synthetic
mercuric sulfide or cinnabar. Flake white and Cremnitz white are made with
basic lead carbonate. Some intense blue colors, including cobalt blue and
cerulean blue, are made with cobalt compounds. Some varieties of cobalt
violet are made with cobalt arsenate. See also
Acrylic paint Acrylic painting techniques
Drying oil Egg tempera
Oil painting Semi-drying oil
Watercolor Oil painting reproduction
References Mayer, Ralph. The Artist's Handbook of
Materials and Techniques Viking Adult; 5th revised and updated edition, 1991.
ISBN 0-670-83701-6