Sketch for a Still Life of Fruit and Flowers, Jan van Huysum, c. 1725 - c. 1735
Jan van Huysum made this drawing with a stick of charcoal soaked in linseed oil. This material was traditionally recommended for drawing sketches. The oil prevents the drawn lines from blurring and lends them greater intensity. The drawing served as a model for a painting. Van Huysum here indicated the most important colours in transparent watercolour.