Notebook, 1993-

MATERIALS & METHODS - Painting - Oil Painting

Characteristics - Painting Methods & Techniques - Materials and Equipment - Work Space & Storage - Manufacture of Pigments - Protection of the Picture

Oil Painting - Imprimatura

A finished glue gesso panel is absorbent. Like a good paper surface, it drinks in colors, and it can be painted upon directly with tempera or watercolor. However, before it can be satisfactory as a ground for painting in oils, its absorbency must be reduced. If a stroke of diluted oil color is put on a gesso panel, too much of the binding oil may be drained off into the gesso, leaving a powdery, unsatisfactory film of color. To avoid this condition, an imprimatura, or weak size, made of varnish or glue may be applied to produce the desirable "egg-shell" surface on which oil colors can best be used.

Materials (one of the three following mixtures should be used)

1. Using a wide brush, quickly apply varnish or shellac to panel with generous strokes. Be sure to cover evenly and completely, leaving no bare spots.

2. Immediately wipe off panel with a clean cloth. This will remove all excess size from the panel and should leave it with an "egg-shell" surface, which will be uniformly absorbent.

A. If the imprimatura dries too quickly to be wiped down, it may leave a glossy film to which oil color will not adhere well. To slow down the drying time slightly, a few drops of stand oil may be added to the varnish-turpentine mixture.

B. If the imprimatura should dry too glossy, rub it down gently with a rag that has been moistened in the appropriate solvent (turpentine for varnish; alcohol for shellac; water for glue, gelatin, or casein).

C. Oil color may be added in small amounts to the varnish imprimatura. This will produce a toned ground. Although it may appear streaky as it is brushed on, it will even out when it is wiped down with a rag. Such grounds, tinted to a middle tone, tend to unify a painting, especially in those early stages when a pure white ground is found by some painters to be disturbing or uninteresting.

D. The imprimatura should dry almost immediately after being wiped down and can be painted upon as soon as it is completely dry. When convenient, it is preferable to allow it to dry overnight before painting over it.

E. Since the absorbency of an oil ground is well balanced for the oil medium, it is unnecessary for the durability of the picture to size an oil-primed support, although the artist may apply a tinted imprimatura for other nontechnical reasons. In similar fashion, an acrylic gesso priming does not require an imprimatura.

[pp. 125-126]

[Kay, Reed. The Painter's Guide to Studio Methods and Materials. Englewood Cliffs, NJ: Prentice-Hall, Inc., 1983.]



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