Focus on this artwork and explain the Painting materials.
Seurat painted the La Grande Jatte in three distinct stages. In the first stage, which was started in 1884, he mixed his paints from several individual pigments and was still using dull earth pigments such as ochre or burnt sienna. In the second stage, during 1885 and 1886, Seurat dispensed with the earth pigments and also limited the number of individual pigments in his paints. This change in his palette was due to his application of the advanced color theories of his time. His intention was to paint small dots or strokes of pure color that would then mix on the retina of the beholder to achieve the desired color impression instead of the usual practice of mixing individual pigments.
Seurat's palette consisted of the usual pigments of his time such as cobalt blue, emerald green and vermilion. Additionally, he used the then new pigment zinc yellow (zinc chromate), predominantly for yellow highlights in the sunlit grass in the middle of the painting but also in mixtures with orange and blue pigments. In the century and more since the painting's completion, the zinc yellow has darkened to brown—a color degeneration that was already showing in the painting in Seurat's lifetime. The discoloration of the originally bright yellow zinc yellow (zinc chromate) to a brownish color is due to the chemical reaction of the chromate ions to orange-colored dichromate ions. In the third stage during 1888–89 Seurat added the colored borders to his composition.
The results of investigation into the discoloration of this painting have been combined with further research into natural aging of paints to digitally rejuvenate the painting.
cobalt blue burnt sienna right vermilion ochre emerald green La Grande Jatte retina dichromate ions zinc chromate