The intervention of old, large-format works of art involves, among other operations, the mechanical study of the textile surface. The objective of this work is to evaluate the mechanical resistance of the painted canvas serving as the stage curtain of “El Circulo” Theater in Rosario, a city in the province of Santa Fe, Argentina. Modern experimental methodology is presented which facilitated the study of the mechanical response of cloth fibers under uniaxial traction at a constant strain rate. The effect of traction on different samples of canvas cloth was determined, on the one hand, through the mechanical effort supported by the weft and, on the other hand, by observing the changes in the weave structure through optic microscopy. Results are presented through the use of this technique and future lines of research are suggested.