A test chart is projected obliquely, with an incident angle ranging between 30° and 75°, on a test specimen, the focusing plane of the image being varied from the specimen surface to 4.8mm from it. The resolution of the image is examined with a microscope in the direction of the specular reflection. Different varieties of paper, and glass plates, ground and polished, aluminium coated by vacuum evaporation, are used as test specimens. A quantity I/R is proposed for the gloss G, that is G=I/R, where I is the intensity of the specularly reflected light and R the resolvable limit of the interval of parallel lines in the image of the chart. With this quantity together with the value of gloss measured by Hunter's multi-purpose reflectmeter, the problem of gloss is discussed.
