A scale of reflection factors of grey is shown with actual specimens and their diffus,ed reflection factors. They are arranged in order so as to give uniform steps with regard to the logarithmic values of the reflection factors, as shown in the accompanying fi gure whose ordinates are given in the logarithmic values of reflection factors. These specimens are painted with grey distemper which are obtained in mixing known proportions of black and white pigments and binding paste. They are very strong against fading and the surfaces are almost perfectly matt.
A similar scale with thirty steps between 85% and 4% reflection factors is now under preparation by the hand of Iwaki Paint Manufacturing Co. Ltd., Osaka. The size of each specimen may be 79cm×55cm large.
