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Oil painting

2007 Schools Wikipedia Selection. Related subjects: Art

   Mona Lisa, Oil on wood panel painting by Leonardo da Vinci.
   Mona Lisa, Oil on wood panel painting by Leonardo da Vinci.
   La donna velata, painted in 1516, Oil on canvas painting by Raphael.
   La donna velata, painted in 1516, Oil on canvas painting by Raphael.
   The Café Terrace on the Place du Forum, Arles, at Night, painted in
   1888. Oil on canvas by Vincent van Gogh.
   The Café Terrace on the Place du Forum, Arles, at Night, painted in
   1888. Oil on canvas by Vincent van Gogh.

   Oil painting is the process of painting with pigments that bound with
   medium of drying oil — especially in early modern Europe, linseed oil.
   Often an oil, such as linseed was boiled with a resin such as pine
   resin or even frankincense, these were called 'varnishes' and were
   prized for their body and gloss. Other oils occasionally used include
   poppyseed oil, walnut oil, and safflower oil. These oils give various
   properties to the oil paint, such as less yellowing or different drying
   times. Certain differences are also visible in the sheen of the paints
   depending on the oil. Painters often use different oils in the same
   painting depending on specific pigments and effects desired. The paints
   themselves also develop a particular feel depending on the media. A
   basic rule of oil paint application is ' fat over lean.' This means
   that each additional layer of paint should be a bit oilier than the
   layer below, to allow proper drying. Traditional oil painting
   techniques often begin with paint mixed with turpentine or artist grade
   mineral spirits or other lean vehicles. As a painting gets additional
   layers, the paint must get oilier (leaner to fatter) or the final
   painting will crack and peel. There are many other painting media that
   can be used in oil painting, including cold wax, resins, and varnishes.
   These additional media can aid the painter in adjusting the
   translucency of the paint, the sheen of the paint, the density or
   'body' of the paint, and the ability of the paint to hold or conceal
   the brushstroke. These variables are closely related to the expressive
   capacity of oil paint. When looking at original oil paintings, the
   various traits of oil paint allow one to sense the choices the artist
   made as they applied the paint. For the viewer, the paint is still, but
   for the artist, the oil paint is a liquid or semi-liquid and must be
   moved 'onto' the painting surface. Traditionally, moving paint was
   accomplished with paint brushes, but there are other methods, including
   the palette knife, the rag, and even directly from the paint tube. Oil
   paint remains wet longer than many other types of artists' materials,
   so a reality in many painter's studios is the removal of oil paint from
   the painting. This can be done with a rag and some turpentine for a
   certain time while the paint is wet, but after a while, the hardened
   layer must be scraped. Many oil paintings reveal evidence of such
   scraping on close inspection, particularly when the surface itself is
   examined. Oil paint dries by oxidation, not evaporation, and is usually
   dry to the touch in a day to two weeks. It is generally dry enough to
   be varnished in six months to a year. Art conservators do not consider
   an oil painting completely dry until it is 60 to 80 years old.

   Oil paint was probably developed for decorative or functional purposes
   in the High Middle Ages. Surfaces like shields — both those used in
   tournaments and those hung as decorations — were more durable when
   painted in oil-based media than when painted in the traditional tempera
   paints.

   Many Renaissance sources credit northern European painters of the 15th
   century with the "invention" of painting with oil media on wood panel —
   Jan van Eyck is often mentioned as the "inventor", however Theophilus
   (roger of Helmerhausen) clearly gives instructions for oil-based
   painting in his treatise, On Divers Arts, written in 1125. The
   popularity of oil grew in 16th century Venice, where a water-durable
   medium was essential. Oil painting was ideal for the northern European
   painters, because the preferred fresco painting media did not work as
   well in their cooler climate. The linseed oil itself comes from the
   flax seeds, and this flax was a common fibre crop. Recent advances in
   chemistry have produced modern water miscible oil paints that can be
   used with and cleaned up with water. Small alterations in the molecular
   structure of the oil creates this water miscible property.

   A still-newer type of paint, heat-set oils, remain liquid until heated
   to 265–280  °F (130–138  °C) for about 15 minutes. Since the paint
   never dries otherwise, cleanup is not needed (except when one wants to
   use a different colour and the same brush). Although not technically
   true oils (the medium is an unidentified "non-drying synthetic oily
   liquid, imbedded with a heat sensitive curing agent"), the paintings
   resemble oil paintings and are usually shown as oil paintings.

Process of oil painting

   The process of oil painting varies from artist to artist, but often
   includes certain steps. First, the artist prepares the surface.
   Although surfaces like linoleum, wooden panel, pressed wood, and
   cardboard have been used, the most popular surface is canvas. Many
   famous paintings were painted on panel. Panels are heavy, so large
   paintings are usually done on canvas.

   Traditional artists' canvas is made from linen, but the less expensive
   cotton fabric has gained popularity. The artist first prepares a wooden
   frame called a “stretcher" or "strainer." The difference between the
   first and second is that stretchers are slightly adjustable, while
   strainers are rigid and lack adjustable corner notches. The canvas is
   then pulled across the wooden frame and tacked or stapled tightly to
   the back edge. The next step is for the artist to apply a "size" to
   isolate the canvas from the acidic qualities of the paint.
   Traditionally, the canvas was coated with a layer of animal glue
   (size), (modern painters will use rabbit skin glue) and primed with
   lead white paint, sometimes with added chalk. Panels were prepared with
   a gesso, a mixture of glue and chalk.

   Modern acrylic "gesso" is made of titanium dioxide with an acrylic
   binder. It is frequently used on canvas, whereas real gesso is not
   suitable for that application. The artist might apply several layers of
   gesso, sanding each smooth after it has dried. Acrylic gesso is very
   difficult to sand. One manufacturer makes a sandable acrylic gesso, but
   it is intended for panels only, not canvas. It is possible to tone the
   gesso to a particular colour, but most store-bought gesso is white. The
   gesso layer will tend to draw the oil paint into the porous surface,
   depending on the thickness of the gesso layer. Excessive or uneven
   gesso layers are sometimes visible in the surface of finished paintings
   as a change in the layer that's not from the paint.

   Next the artist might sketch an outline of their subject prior to
   applying pigment to the surface. “Pigment” may be any number of natural
   substances with colour, such as sulfur for yellow or cobalt for blue.
   The pigment is mixed with oil, usually linseed oil but other oils may
   be used as well. The various oils dry differently creating assorted
   effects.

   Traditionally, an artist mixed his or her own paints for each project.
   Handling and mixing the raw pigments and mediums was prohibitive to
   transportation. This changed in the late 1800’s, when oil paint in
   tubes became widely available. Artists could mix colors quickly and
   easily without having to grind their own pigments. Also, the
   portability of tube paints allowed for plein air, or outdoor painting
   (common to French Impressionism).

   The artist most often uses a brush to apply the paint. Brushes are made
   from a variety of fibers to create different effects. For example,
   brushes made with hog’s bristle might be used for bolder strokes.
   Brushes made from miniver, which is squirrel fur, might be used for
   finer details. Sizes of brushes also create different effects. For
   example, a "round" is a pointed brush used for detail work. "Bright"
   brushes are used to apply broad swaths of colour. The artist might also
   apply paint with a palette knife, which is a flat, metal blade. A
   palette knife may also be used to remove paint from the canvas when
   necessary. A variety of unconventional tools, such as rags, sponges,
   and cotton swabs, may be used. Some artists even paint with their
   fingers.

   Most artists paint in layers, a method first perfected in the Egg
   tempera painting technique, and adapted in Northern Europe for use with
   linseed oil paints. The first coat or " underpainting" is laid down
   first, painted normally with turpentine thinned paint. This layer helps
   to "tone" the canvas, and cover the white of the gesso. Many artists
   use this layer to sketch out the composition. This layer can be
   adjusted before moving forward, which is an advantage over the
   'cartooning' method used in Fresco technique. After this layer dries,
   one way the artist might then proceed is by painting a "mosaic" of
   colour swatches, working from darkest to lightest. The borders of the
   colors are blended together when the "mosaic" is completed. This layer
   is then left to dry before applying details. After it is dry, the
   artist will apply "glaze" to the painting, which is a thin, transparent
   layer to seal the surface. A classical work might take weeks or even
   months to layer the paint. Artists in later periods such as the
   impressionist era often blended the wet paint on the canvas without
   following the Renaissance layering and glazing method. This method is
   called "Alla Prima." When the image is finished and dried for up to a
   year, an artist would often seal the work with a layer of varnish
   typically made from damar gum crystals dissolved in turpentine.
   Contemporary artists increasingly resist the varnishing of their work,
   preferring that the surfaces remain varnish-free indefinitely.

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