Stresses induced in a silicon wafer by mask edges or recessed oxides may be studied by the means of x‐ray topographs. The contrast of such topographs has been previously studied using the Blech and Meieran theory [J. Appl. Phys. 38, 2913 (1967)] for the stresses and Kato’s theory [Acta Crystallogr. 16, 282 (1963)] for the diffraction. Simulations using Takagi’s equations [S. Takagi, Acta Crystallogr. 15, 1131 (1962)] show that this model is not correct: the magnitude of stresses is too large and should lead to additional fringes in the image. This could not be predicted using Kato’s theory where the interaction between the wavefields and the most deformed areas of the crystal is underestimated. It suggests that a relaxation occurs along the surface to decrease the value of the stresses.