The correspondence between artists Robert Zünd (1827–1909) and Rudolf Koller (1828–1905), ranked today among the most significant 19th-century landscape painters in Switzerland, is the point of departure for this research project supported by art technology. Considering the nature of their paintings, their letters, especially in the 1860s and 1870s, reveal a surprising interest in issues of technique and indicate that, rather than traditional methods, it was the latest technical innovations that enabled them to paint like great Renaissance artists or Dutch landscape painters of the “golden” 17th century. An evaluation of relevant letters will be complemented by a technological analysis of selected paintings by each artist in which the techniques and products described were applied, and the findings will discussed in a broader context. The project outcomes are to be published as the seventh volume in the series KUNSTmaterial.