3.10 Thread count
Canvas studies, as described in publications prior to Van de Wetering, were not sufficiently accurate to establish whether two canvases were cut from the same bolt of cloth. For example, when thread density is measured at only a few places and reported as single integers in the vertical and horizontal directions, there is not enough information to reliably conclude that there is a match. In the case of Rembrandt’s canvases, which often show an irregular weave, a more elaborate method was developed. Van de Wetering took counts of each painting at various places in both horizontal and vertical directions, after which average values were worked out. To form an impression of the degree of irregularity of the thread density, the spread of the counts was also recorded. Depending on the number of available X-radiographs and the size of the painting, the thread density was measured six to more than 20 times in each direction. If the average densities and spreads of two canvases match, these canvases may come from the same bolt.