Origin and technology of the Georgian brick at Fade Mansion, Dublin, built c. 1728

Abstract

This paper studies the provenance and firing technology of the Fade Mansion brick. The microstructure was studied with scanning electron microscopy (SEM), mineral associations and transformation were determined with X-ray diffraction (XRD) and petrographic analyses. The results evidenced that the bricks were made with a decalcified, silica-based clay of glacio-fluvial origin, gathered  locally. This agrees with the position of the Mansion on a terrace of the River Liffey, and with previous research on historic bricks  made with boulder clay. They were fired in kilns in an oxidising atmosphere. The rubbers at window heads reached lower  temperatures which resulted in low vitrification, leading to weathering. Initial vitrification structures generally concur with the occurrence of clay minerals, indicating temperatures of c. 800°C. Continuous vitrification is associated to the disappearance of clay minerals, the sintering of hematite and/or high-temperature phases and mica transformation, indicating a wide temperature range  >950-1200°C, which agrees with the inconsistent brick properties.