Techniques Paper

OIL, TEMPERA AND ACRYLIC PAINTING TECHNIQUES

This paper is written to be relevant to any oil, tempera or acrylic painting and, therefore, no particular work is included for reference.

OIL PAINTING

Let’s begin with the canvas of a painting, the base for a finished work. We are used to thinking of canvas as material attached to a wood frame or panel. This material would be a piece of cloth made from flax, hemp or cotton fibers. Texture and weight of the canvas can vary from coarse to fine. These started to be used in the early Italian Renaissance instead of frescos, as frescos would deteriorate due to damp environs, particularly of Venice and other places in Europe, whereas works on canvas endure much longer.  Remember the major advantage of canvas over wood as a base for painting is that it is much easier to move around as it is much lighter, specifically before framing.

The canvas first needs to be “sized” (prepared) with a liquid containing animal glues, then a white preparatory layer known as GESSO is applied to smooth out any irregularities in the canvas surface, thus providing the optimum base for a variety of media. Oil paint should not come into direct contact with a bare canvas.

Then comes the UNDERPAINTING, which helps establish areas of dark, light or color. Underpainting is crucial to the development of the finished surface as it gives depth to the work.

Now it is time to begin – a sketch is made on the prepared canvas with charcoal or thinned paint. The basic rule being FAT OVER LEAN, meaning each additional layer of paint should contain more oil than the previous one.

OIL SKETCHES were also used as a study before the final work. These were pioneered by 16c Italian painters, sometimes worked on paper, but also on canvas or panel/board.

OIL PAINT – Oil paint was first used by Indian and Chinese painters in W. Afghanistan between 5-10c but did not gain popularity in Europe until the 15c when Italians started to use oil paint in place of fresco and tempera, and has continued in popularity to this day. Commonly, linseed oil is used as the carrier/binder for the pigment/color. This procedure can be traced back to the 5-6c. Pigments of color are bound with the oil and different properties in the oil of choice create different finishes, such as less or more yellowing and a difference in the drying time. Many of the ground pigments used by early artists were of a toxic nature, as they contained ingredients such as lead, arsenic and mercury.  Apparently Van Gogh used to eat his oil paints in times of his mental instability and it is thought that this may have contributed to his death in 1890.  Artists had assistants who would prepare their paints for them, which was a time consuming procedure and painting on canvas was always done in the studio.

In the Early Renaissance, oils were used in combination with other paint media, particularly in transparent ‘glazes’ on egg tempera paintings. By the 15c oil painting techniques had been refined by the N. European artists and by the 16c oil had become the dominant painting medium.

The main advantage of oil paint is that is does not change color on drying. However, it can take as long as a year to dry properly. Today there are several different grades of paint available and, of course, they are now in tubes, thanks to the invention by an American in the mid 1800s.

In oil painting one usually works from dark to light with a number of different BRUSHES, although other methods of paint application, such as palette knife and sponge or cloth, and of course your fingers can be used.

BRUSH TYPES:

Hogs hair is used for bold strokes and impasto textures.
Fitch hair and mongoose hair are fine and smooth and good for portraits and detail work.
Sable hair is the most expensive and keeps the finest point and a good memory, i.e., it keeps its shape.
Synthetic brushes have come onto the market and are durable and cost effective.

BRUSH SHAPES:

ROUND is pointed brush used for detail work
FLAT is used to apply broad swaths of color
BRIGHT is a flat with shorter brush hairs
FILBERT is a flat with rounded corners
EGBERT is a very long filbert and rare

When looking at these brushes you will get an idea of what type of stroke they produce on the canvas.  Once the work is finished to the artist’s satisfaction he may wish to varnish the work which will assist in the preservation over time.

TEMPERA

Tempera is a permanent fast drying medium consisting of colored pigment mixed with a water soluble binder, usually egg yolk. Tempera paintings are very long lasting and some exist from the 1C AD. This medium continued in use until the 1500s when it was superseded by the use of oil paint.

Tempera paintings have been found on early Egyptian Fayum funerary portraits, of which we have a fine example in our museum and were also used in religious icons from the Byzantine era.  The Egyptian paintings were mainly very well preserved due to the dryness of the climate and the fact they were funerary and therefore underground.

TEMPERA is traditionally created by hand grinding dry powder ingredients into binding agent or medium such as egg yolk. A small amount of pigment is placed on a palette or bowl adding an equal amount of binder and mixing with a few drops of distilled water. Adding the egg yolk requires skill and practice as the membrane needs to be pierced whilst being held aloft! The more egg yolk added the greater the transparency of the work. The yolk is never used alone as it dries too quickly and cracks, so water, white wine or vinegar can be used to modify the consistency of the tempera.  This paint cannot be stored and needs practice to get the right result quickly.

It is always painted on a hard surface, never canvas, as it is not a flexible paint. Some pigments used by mediaeval painters contained toxic materials such as lead, arsenic and mercury. Tempera is usually applied in thin semi-opaque or transparent layers. Tempera painting allows for great precision when used with traditional techniques that require application of numerous small brush strokes applied in a cross-hatching technique. When dry, it produces a smooth matt finish. Because it cannot be applied in layers as oil can be, tempera paintings rarely have the deep color saturation achieved with oil painting. Unvarnished tempera paintings resemble a pastel, but obtain a depth of color when varnished. Tempera colors do not change as they age.

ACRYLIC  Acrylics differ from oil paints in that they have a much shorter drying time, sometimes as little as 10 minutes, and are water soluble. These types of paint eliminate the need for turpentine and gesso and can be applied directly on to the canvas. As with oil paints though, there are different grades of tube paint ranging from student to artists quality.

The drying time can be extended with the addition of water, sprayed or poured, to the paint and with other types of medium now on the market. There are also moisture retaining palettes on the market which keep the paints moist for several days.  Again, these acrylic paints can be made to vary in thickness or thinness depending on the type of work/finish the artist has in mind.

As with oil painting, it is up to the artist whether to varnish their work or not. Varnish will give more depth to the finished acrylic work.

The same types paint brushes can be used as those described in the oil painting section of this paper, but usually one would use a less expensive brush with acrylic paint.

Prepared for the Santa Barbara Museum of Art Docent Council by Ann Hammond, 2014.

BIBLIOGRAPHY

Artists’ Techniques and Materials, Antonella Fuga

The Craftsman’s Handbook, Cennino d’Andrea Cennini

SBMA website – research paper by Gail Elnicky for the Fayum Funerary Portrait

SBMA website – Artists Techniques: the Development of  Impressionism by Ellen Lawson

The Artist’s Manual, edited by Angela Gair for Chronicle books

Windsor and Newton website