Een verkeerde loop in ’t vuur: an initial investigation into what Dutch archival sources can tell us about techniques and problems in the production of 17th and 18th century Dutch tin-glaze tiles

Technical art-historical archival sources can be invaluable for our knowledge and understanding of the origin and preparation of materials as well as the production techniques used to make ceramic objects. The information provided could also aid our understanding of the factors that influence susceptibility for degradation as well as provide details which could aid provenance studies. Most early written technical sources on tin-glaze production are in the form of treatises written by educated observers rather than the potters themselves. Also, while being of significant comparative interest, such treatises are not directly related to either Dutch tin glaze or tile production. Luckily a number of 17th and 18th century primary written sources and archival records dating as far back as 1620 have survived in the Netherlands in the form of recipe books, kiln records and legal documents that contain information directly relating to tin-glaze tile production. These documents provide insight into the composition and preparation of the clay and tin glaze as well as the problems encountered with specific recipes and firing. In addition, pottery inventories provide information concerning the use and import as well as the cost of the raw materials. More than 150 recipes for clay mixtures, tin glaze, ‘kwaart’ (lead glaze or ‘coperta’) and glaze colours can be found in these early sources relating to factories in Delft, Harlingen, Makkum, Utrecht and Rotterdam between 1659 and 1862. The recipes not only show variations in the composition and ratios of the materials that make up a tin glaze, primarily ‘masticot’ (sand and ‘soda’) and ‘tinas’ (lead, tin), but also describe the variations in quality and provenance of raw materials for each recipe. Furthermore, information concerning clay mixtures is also documented as well as details regarding kiln structure and firing problems. This preliminary investigation into Dutch archival records is part of broader research project into changes in the production of 17th and 18th century Dutch tin-glaze tiles and its relation to glaze stabilit