Richard Murdock

Basic Practices In Painting

Brushes used by the Flemish were made of hog’s hair bristle or of squirrel hair for detailing.

The Flemish painters painted thinly on a bright white ground on wood panel sealed to make it non-absorbent. A drawing was transferred after careful studies had been done. Then a general tint was applied (imprimatura), through which the priming is visible, in pale flesh tone, brown, or even gray. [Rubens painted on a light gray.] This was to assist the middle tints of the picture and never excluded the still lighter priming. Shadows were painted first as transparent glazes that allowed the light to pass through and reflect off of the white ground. Then lights were built up gradually from there.

In this thin, transparent method of painting, grounds of Verdigris and Umber are discouraged because they kill the colors that are applied over them, the Flemish tending always towards warm shadows.

“The painting was executed as much as possible at once, and therefore, occasionally, in portions at a time. This last system was, by degrees, so far departed from, that the design, especially when of large dimensions, was dead colored from a finished sketch, so as to avoid alterations in the more complete work.” Eastlake p.484

In the carnation of the work, colors were applied in one coat with tints mixed to the local hues required.

“Later painters employed a dusky priming, serving as a middle tint for the shadows rather than the lights.” Color: white lead, black, red ochre, and sometimes a little umber.

Linseed oil was still made clear and drying by the use of calcined bones. Medium was mixed using a hard resin like mastic or amber mixed 1:3 with linseed oil. “The use of oleo-resinous vehicles…rendered a final varnish …needless.” Diluted with an essential oil, “the consistency of the vehicle itself, except when employed for rich shadows, was at all times such as to be compatible with the sharpest execution.” Drying was further increased by addition of metallic oxides.

When a thinner vehicle was used, the work was coated with an essential oil varnish. In Italy liquid resin or balsam was dissolved or diluted in spirit of turpentine or other volatile oil. It is written that the best varnish is pure resin of fir (olio d’abezzo) warmed gently and mixed with a greater portion of rectified clear petroleum (naptha) and applied warm to a warm surface, very thinly with a brush. It is transparent, has a good sheen (like fresh paint) and does not yellow over time. Also, it dries very quickly, not trapping dust.

But the very thin essential oil varnish alone was not enough to protect from moisture in the damp North where mastic was added to increase body and eventually completely replaced the liquid resin of the silver fir (Abies pectinata or taxifolia) or larch (Venetian turpentine). Works that needed to be especially protected from humidity or moisture were always varnished with an oleo-resinous mixture such as linseed and mastic as in the medium described above.

“Among the technical improvements on the older process may be especially mentioned the preservation of transparency chiefly in the darker masses, the lights being loaded as required. The system of exhibiting the bright ground through the shadows still involved an adherence to the original method of defining the composition at first, and the solid painting of the lights opened the door to that freedom of execution which the works of the early masters (lacked).” [In the early school, even the lights were painted translucently to make use of the light ground.]