Cross section of the paint sample

Cross section of the paint sample taken from the yellow writing on the calligraphy tile: (1) White ground (2) Dark blue paint layer in the background of the tiles (3) Blue paint layer composed of the mixture of cobalt blue and ultramarine (4) Green paint layer found between the blue and yellow layers.The paint layer is composed of the mixture of the second and the fourth layers (5) Yellow paint layer of the writing