The process of painting with pigments using a medium of drying oil as the binder is called oil painting. The commonly used oils are linseed oil, poppy seed oil, walnut oil and safflower oil. The properties of the oil like yellowing and drying time play a big part in the selection of the oil. An artist might use different oils in his work depending on the effects desired and the pigments used. A varnish effect can be created by boiling the oil with resin-like pine resin or frankincense. The origin of oil painting s dates back to their use in Buddhist paintings in central and western Afghanistan between the fifth and tenth centuries. It attained popularity around the fifteenth century. It migrated towards the west in the Middle Ages. As the advantages of oil painting became evident it became the principal medium for creating artwork. During the Renaissance period in Europe, oil painting techniques replace the use of tempera paints. Currently, water-miscible paints are available. These paints have an emulsifier to enable them to be thinned using water rather than thinner. This reduces the drying time from 1 to 3 days from 1 to 3 weeks.
The earliest paintings discovered date back to 650 AD and the are located in Afghanistan. These paintings were created by Buddhist artists. The earliest paintings include a wide variety of pigments and binders and some also had a varnish layer. The use of tempera which is pigment mixed with egg whites or yolks originated in Europe in the fifteenth century. The credit of painting with oil on wooden surfaces goes to Jan Van Eyck.
Theophilus’s treatise called Various Arts provides instructions for oil painting. During this period it was used for painting on sculptures, carvings and wood fittings. The earlier paintings used wood as a surface but canvas became more widely used as it was cheaper and easier to transport. Venice was a leader in the transition and also known for sail-canvas. Paintings made on metal were expensive but allowed intricate detailing. The popularity of oil painting spread through Italy starting from Venice in the late fifteen century.
Normally oil painting techniques start with the artist stretching the subject on the canvas using charcoal or paint which has been thinned. The use of solvents to make the paint thinner they can be used to clean brushes. One of the rules to be followed is each new layer of paint should contain more oil than the earlier layer to allow proper drying or else it might result in the painting cracking and peeling. This type of application of painting is called fat over lean. The other media that can be used with the oil include cold wax, resins and varnishes.
This media helps in the translucency of the paint, the body of the paint and helps to hold the brushstrokes. The main tool used in painting on surfaces is paintbrushes but other tools like palette knives and rags can also be used. As oil paintings tend to dry slower it allows the artist to change the colour, texture or form. The drying process in oil paintings is by oxidation and not evaporation and hence they take around two weeks to dry completely.
The support used in oil paintings namely linseed oil is derived comes from the flax seeds. The other support linen also comes from the flax plant. Other oils like safflower oil or the walnut oil or poppy seed oil are sometimes used in lighter colours like white because they do not yellow on drying as compared to linseed oil. The disadvantage of using these oils is that they drying more slowly. The innovations in chemistry have resulted in the production of modern-day water miscible oil paints that can be used and cleaned with water.
The artist’s canvas is normally made from linen, but in terms of popularity, the use of cotton fabric which is less expensive has gained acceptance. The artist begins by preparing a wooden frame called a stretcher or strainer. The main difference between stretchers and strainers is that stretchers are adjustable while strainers are rigid and cannot be adjusted. The standard procedure is that the canvas is drawn across the wooden frame and tacked or stapled tightly to the back edge. Normally the canvas was coated with a layer of animal glue as the size and then primed with lead white paint, sometimes chalk was added. The panels were also prepared with a gesso a mixture of glue and chalk.
Modern acrylic gesso is composed of titanium dioxide and contains an acrylic binder. It is frequently used on canvas as compared to real gesso which is not suitable. The application of several layers of acrylic gesso and sanding them is difficult. The gesso can be made to a particular colour but the common one is white. The gesso helps in drawing the oil into the porous surface. Standard sizes for oil paintings originated in France in the nineteenth century. The most widely used surfaces in canvas are linoleum, wooden panel, paper, slate, pressed wood, masonite and cardboard. The disadvantage of using the panel is that they are heavier, expensive and are difficult to transport. For fine detailing a wooden panel is preferred.
Usually, an oil painting is made by mixing pigments of colours using an oil medium. The different colours are obtained by way of purchase and mixing before the start of the painting. Additionally, some shades are developed in the course of the painting by mixing small quantities of colours. A palette is traditionally used for mixing colours. Currently, pigments may be natural or synthetic in nature. In the past pigments were based on plants and minerals and that is the reason they proved to be unstable over long periods of time.
Normally the pigment is mixed with and the use of various oils creates assorted effects.
Earlier artists used to mix their own paints from raw pigments which made portability difficult and kept most painting activities within the studio. This changed with the advent of oil tunes in the 1800. This was made possible because of the American portrait painter John Goffe Rand's invention of the squeezable or collapsible metal tube in the year 1841. A brush is the most widely used tool by the artist to apply the paint. Brushes are composed of a variety of fibers. Brushes made with hog bristle are used for bolder strokes and impasto textures. Fitch hair and mongoose hair brushes are fine and smooth in nature, and hence they are used for portraits and detail work. The more expensive red sable brushes are made from weasel hair. The kolinsky sable is one of the finest quality of brushes available. These brushes have fibers made from the tail of the Siberian weasel. The use of synthetic brushes has gained acceptance as they are durable and cost-efficient as well.
Many synthetic brushes have been marketed in the last decade. They are durable, good and cost efficient. Traditionally painting is applied in glazes or indirect painting. This egg tempera technique was perfected and applied by the Flemish painters. This technique, used pigments ground in linseed oil. In this technique the first layer painted with egg tempera or turpentine-thinned paint. This layer helps in toning the canvas and covering the white of the gesso. After the drying of this layer the artist might then paint an assortment of colour swatches, starting from darkest to lightest. The borders of the colours get blended when the mosaic is completed and then dried. The details are applied later. The artists who were know as the Impressionist often expanded on this wet-on-wet method, blending the wet paint on the canvas without layering and glazing. This method is named Aalla Prima. This method derives its origin due to painting outdoors because while painting outdoors the artist did not have the luxury to let each layer of paint dry before adding a new layer. Both the techniques are combined currently by artists to achieve the depth of layers through glazing. When the image is completed and has dried the artist often seals the painting with a layer of varnish that is made from dammar gum crystals dissolved in turpentine. The advantage of using varnishes is that they can be removed without disturbing the oil painting. This facilitates the process of cleaning and conservation.