A goniospectrophotometer is used to analyze the hack-scattered light, in the visible range, by a 0.3 cm{sup}2 surface. The measurement is non-destructive, without contact and can be implemented in situ. For a metallic surface, the reflected intensity is measured as a function of the back-scattered angle. The probability density of the normal to the surface is then deduced. The ratio roughness rm.s./correlation length is calculated. The method is applied to characterize the different techniques for gold backgrounds in primitive European paintings. For a non-metallic surface, the reflected intensity is measured as a function of the wavelength. The spectrum is compared with a data bank of mineral pigment spectra. The comparison allows us to identify pigments and, moreover, to deduce the surface state of the painting layer Examples of Egyptian and modern paintings will be presented.
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