Oil painting technique
Oil painting is the main pictorial technique used since the fifteenth century. It is applied on various bases without changing the final appearance, but the most commonly used medium is the canvas, because of its lightness and because it is more suitable for large paintings.
Oil painting uses oil as a medium. It is the main pictorial technique since the fifteenth century. This technique is known at least from the treatise of the monk Teófilo of the year 1100.
The bases on which the oils are applied can vary without changing the final appearance. The technique of preparation of the bases varies, because the materials have different points of absorption. Since the Baroque, in the seventeenth century, the canvas is the most popular support, since it was lighter than the table, a support used by the Flemish school.
Support for oil painting:
The canvas is the most used support for oil painting, due to its lightness and to which it lends itself more for the realization of large-scale works and for outdoor painting.
The fabrics most commonly used to make the canvases are linen and hemp. Fabrics such as cotton, which has a very large porosity and is very hygroscopic, or silk, which is broken by the action of oils, do not serve this purpose. . It also matters how the fabric is woven, the spine-fish and the grained tissue are fit.
The canvas should be placed on a wooden frame, and is suitably tensioned.
The preparation of the frame is done by means of a primer, which leaves the cloth ready to receive the paint. The brightness of the painting and its duration depend on it. The primer seeks to protect the canvas and eliminate the porosity of the same, for it is applied a first coat of glue, recessed with ammonia and glycerin, so that the fabric does not rot or stiffen. Then a mixture of sweet glue, zinc oxide and calcium carbonate is applied. It can be applied in several layers, with a brush or spatula. Always let the old hand dry well and scratch before the next application. So that the bottom does not absorb, we use varnish-based insulators.
The binders of color in oil painting:
In oil paint they are used as binders for the dissolution of pigments, fatty oils and some essences and resins, which provide qualities to avoid contractions and roughness.
The most commonly used oils are flaxseed, which is obtained from flax seeds, and is the most drying oil. The oil of walnuts, is obtained from the pressing of ripe nuts, and the poppy oil, from the pressing of white poppy seed. These two do not yellow as easily as flaxseed oil.
The essence most used is turpentine, obtained from the distillation of pine balsam. It is used to apply fine colored films.
The resins can be hard, like copal and amber; or soft like mastic and dammar.
Application of colors in oil painting:
Direct oil painting or painting "alla prima", is the fastest method, where you work on the final effect from the beginning. It demands a great command and experience.
The application by layers is a very old technique, in the lower layer you get the drawing (shape), with the shading and a sketch of the color. In the upper layer, the representation of the chromatic effect is performed.
One of the most used techniques in oil painting is the application of color by glazes, that is, by transparency. Light, fluid layers are applied, which always go from light to dark.
When the paint is finished and well dried, a layer of protective varnish is applied.
The varnish can be used for other uses, added to the colors to give them shine and solidity, it can be used to separate two layers of color.