As the largest German city and the seat of the elector-archbishop, Cologne was one of Europe’s most vibrant artistic centers during the later fourteenth and fifteenth centuries. Besides its export market, the city offered ample opportunities for its artists. Around 1500, Cologne’s religious institutions alone had some 450 altars, two-thirds of which were located in parish and collegiate churches. Even though not all were decorated with paintings, most were. Scholarly estimates of the rate of survival of art from this period range from 2 percent to upwards of 50 percent. Regardless of the actual figure, there exists a substantial corpus of paintings believed to have been made in Cologne. These have been thoughtfully studied in numerous excellent exhibitions, such as Herbst des Mittelalters: Spätgotik in Kőln und am Niederrhein (1970), and museum catalogues, including Frank Günter Zehnder’s Altkőlner Malerei (1990), about the Wallraf-Richartz-Museum’s holdings. Excepting Stefan Lochner, the other painters are anonymous with names such as the Master of St. Veronica or the Master of the Small Passion. Questions of attribution, dating, and provenance, among other issues, have long challenged scholars.

In 2009 the Wallraf-Richartz-Museum & Fondation Corboud in Cologne and the Doerner Institut in association with the Bayerische Staatsgemäldesammlungen in Munich jointly received a major research grant from Germany’s Federal Ministry for Education and Research. Their task was to undertake a detailed scientific investigation of twenty-nine panel paintings by major Cologne masters in their collections that date to the first half of the fifteenth century. These are now single pictures divorced from their original formats (such as being a segment of an altarpiece), stripped of their original frames, and removed from their original settings. The research team of eleven specialists selected this group of paintings to see what the language of their materials, to borrow the volume’s title, might reveal about production practices or about the characteristics of a specific workshop or master.

The book’s essays and catalogue are highly technical. Each painting underwent noninvasive examination, which included dendrochronology; x-ray and infrared reflectography; microscopic assessment of the grounds, colors, binding media, and application of metal leaf; and methods and patterns of incised and punched ornament. Pentimenti and other particularities are noted when significant. Roland Krischel provides a brief but useful art historical introduction to Cologne painting and its scholarship.

Most of the chapters address specific physical layers of the paintings. For instance, chapter 3 studies wood. The majority of Cologne pictures are painted on oak or walnut panels. Pine was employed only rarely. Occasionally a combination was used, as in the case of Lochner’s Last Judgment (ca. 1435, cat. nos. 18–19), where the center panel is oak and the wings are walnut. Most oak came from Poland and the Baltic region, though a less dense and lower-quality oak grew in the area of Cologne and the Netherlands. The eastern European oak averaged about fifteen years of age, based on its sapwood, before it was harvested. Dendrochronological evidence sometimes disproves current art historical dating. This chapter also explores painting formats and the construction of the panels, including types of joints, wood preparation, frames, hinges, and other hardware. Subsequent chapters cover preparatory grounds (chapter 4); compositional layers (chapter 5), including underdrawings and the use of written color notations (figs. 77–79); metal leaf and ornament techniques (chapter 6); pigments, binders, and other painting materials (chapter 7); and conventional painting formats and functions (chapter 8).

The final two chapters contain analyses of the project’s findings. The Master of St. Veronica has long been celebrated as the leading early fifteenth-century Cologne painter. Based on the technical information, however, most of the formerly attributed pictures, including his two namesake paintings in London and Munich, are now ascribed to the Master of St. Lawrence, with whom he may have collaborated. The researchers identified a second generation of painters active between 1420 and 1440 who exhibit formal and stylistic similarities suggesting a large workshop with changing members. The third dominant group consisted of Lochner and the Master of the Heisterbach Altar. Was Lochner in Cologne prior to his first documentary mention in 1437? The use of common brocade patterns, among other features, might link him with the workshop of the Master of the Heisterbach Altar. One of Lochner’s most famous works, the Madonna of the Rose Bower in Cologne (cat. no. 20), likely formed the left wing of a diptych rather than being an independent picture.

The general thematic, stylistic, and qualitative homogeneity of the city’s painting during these decades suggests the dominance of a small number of cooperative workshops who maintained a distinctive Cologne brand or looked both for local consumption and for export. This stimulating book, with its excellent illustrations, offers a methodological and technical model that could be adopted for exploring the distinctive patrimonies of other leading artistic centers.