Contrasting recipes for the kiln furnitures of the faience manufacture Granges-le-Bourg (Haute Saône, France)

Thirty-nine samples of kiln furniture or technical ceramic (firing plate, saggars, spacers, props, wads) and six samples of building ceramics (bricks, tiles) from the manufacture of Granges-le-Bourg were studied by optical microscopy, X-ray fluorescence, X-ray diffraction and scanning electron microscopy. The kiln furniture is chemically inhomogeneous and belong to a CaO- + MgO-poor (firing plate, saggars) or a CaO- + MgO-rich (props, spacers, wads) group. Bricks and tiles pertain to the first group which was manufactured using decarbonatized top layers of local Triassic dolomitic marls. For the second group, the deeper layers were used. Plate and saggars are covered with a tin oxide opacified glassy coating with no significant reaction zone to the body