A brush and a knife
Seascape at Les Saintes-Maries-de-la-Mer
In addition to brushes, Van Gogh also used a palette knife in making this painting. With the knife, he spread the paint into a glossy, transparent layer in some places. This created the effect of sunlight on the waves and brought the colours to life.
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Reflected light image of brushstrokes, reworked with a palette knife.
In some places, the palette knife smoothed out the distinctive texture of the brushstrokes. Van Gogh did not often use a palette knife.
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Various palette knives were available from art supply shops, as shown by this page from the catalogue of art supplies of the Paris paint dealer Lefranc (1922).