Industrial production of white earthenware in the Johnston-Vieillard manufactory (19th century): recipes evolution and production strategies
Résumé
The aim of this paper is to present research conducted on the ceramic productions of a French ceramic manufactory in Bordeaux. The Johnston-Vieillard manufactory produced, between 1845 and 1895, a special type of ceramic called “white earthenware”. Although general documents remain (such as ceramic treatises, World Exhibition's catalogues, lawsuits, correspondences), factory archives (that were either lost or destroyed) are severely lacking in order to document the production techniques (choice of raw materials, recipes, firing conditions, division of labor and life in the manufactory, …). Recently, a lot of pieces and remains of white earthenware (wasted materials and elements used at the different stages of the chaîne opératoire) were discovered during an excavation performed in the ancient factory area. In the present study, we focused specifically on the modifications over time of white earthenware production.
We examined six groups of sherds representative of different production periods of the factory. These sherds came from the available and abundant wastes found during the excavation located in the ancient waste dumps of the manufactory. A total of 150 fragments – 70 biscuits and 80 glazed white earthenwares – were selected for analysis. As a matter of fact, composition of bodies and glazes were investigated using a combination of analytical techniques that included Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS), Particle Induced X-Ray and Gamma Emission (PIXE-PIGE) and X-Ray Diffraction (XRD).
Analyses showed significant differences on chemical composition of glazes and bodies during the different stages of the factory life. Thus, it is possible to make assumptions concerning the recipes used for paste and glaze during the different chronological periods. Of course, these recipes are compared to those available in the literature of the 19th century. Finally, hypothesis about adaptability of the glaze to the paste are discussed. The correlation between the modifications of glazes and bodies composition with the variations of the coefficient of thermal expansion.
The aim of this work is to contribute to document an industrial production of white earthenware throughout the 19th century. Results obtained on the characterization of the ceramic production technologies and on the modification over time of the recipes (glazes and bodies) will be presented.