During the Carolingian time the sacrament of baptism is performed on the newborns, which generalized the use of baptismal fonts. However, the stone-made fonts’ existence before the XIIth century isn’t proven and they were probably made with wood. In 842 during the Synod of Reims, the archbishop Hincmar emphasise the use of stone for baptismal fonts, as it was already brought to the fore during the Synod of Lérida in 524. The use of stone is emphasised again in 1290 by Guillaume Durand, a liturgist who, more than practical reasons, outlines the symbolical reasons.
To work with hard stone, multiple tools are needed : points, flat chisels and the bit. Then, the drawing is applied on the different flat areas, the edges are engraved with a chisel, the heart is cleared using a bit and ambossed parts are crafted with points, flat and dented chisels. The workmanship is done using a gouge and chisels. The finished pieces are delivered using water ways and assembled on the destination site. One cubic meter of blue stone was 2.7 tonnes. We can see then some standards in the craft of stone tank : cubical, the baptismal fonts are constituted with a square base and a square tank.