The strain distribution in raw stretched canvas, impregnated lining canvas and a painting stretched by the 'Dutch method' was measured using a grid system. The purpose was to provide some basic empirical data with which to describe the various situations, and to serve as a reference point in the construction of a mathematical model. The most significant results were the heterogeneous nature of the strain distribution, the role of the Poisson effect in the distribution, the influence of the anisotropy of canvas and the occurrence of the largest strains at the corners of stretched canvas.