An Investigation of Pigments and Technique in the Cezanne Painting, “Chestnut Trees”

design area. Samples were then taken from twenty different tones of paint2, the pig t oLrticles were dispersed, mounted in Aroclor 51423 (refractive index, nD 1.66) and identified using a polarizing microscope. Identifications were made by using characteristic optical and physical properties. The optical properties included relative refractive index, isotropy and anisotropy, birefringence and type of extinction. The physical properties included color in plane polarized light and between crossed polars, degree of transparency or opacity, size, shape, surface texture, cleavage, fracture, homogeneity and degree of agglomeration. Pigment particle size ranges were measured and the percentages of pigments in a mixture were estimated by volume. Apochromatic objectives were found to be essential for studying these samples, especially for seeing the identifying properties of pigment particles because they most frequently fall into a very low 0.5-10 pm range. One sectionak fragment was taken from the painting and mounted in viscous Aroclor 1260 for the purpose of measuring typical paint layer thicknesses.