Here is a painting produced by J. Van Os. Jan van Os (1744-1808) became the Director of the Academy at The Hague and is known to have exhibited twelve paintings – mostly flower pieces – at the Society of Artists in London between 1773 and 1791.
The panel
The original is painted on a single piece of mahogany (787mm by 587mm) with the grain running vertically. The panel is 10mm thick with a 30mm bevel to 5mm at the edge.
Underdrawing
Jan van Os’ drawing was copied and transferred by pencil onto the layer of lead white and chalk. In places, the original underdrawing was visible to the naked eye because the paint had become more transparent with age (for example, in the bunch of white grapes).
The paint layers
Following the pencil underdrawing, areas of the painting were blocked-out in pale oil paint. These flat areas of colour provided a context for those subjects that were to be painted first. Each type of fruit or flower was painted in a technique that suited its visual characteristics, almost proving that the painting was a definite result of an experienced painter.
The pigments
The pigments were typical of late eighteenth-century painting. Chalk and lead white have already been mentioned as colourless or white pigments. Mixtures containing chalk tended to be used for transparent layers, and mixtures containing lead white were for light-tone opaque layers.
The medium
The paint was made of poppy oil. This dries much slower than linseed oil, but tends to discolour less with age. The high tones of Jan van Os’ flower paintings would have been exposed to yellowing and he was evidently prepared to work slowly in order to gain the advantage of poppy oil’s long-term usage.
W Andrews
EDPhotography3L 