An Investigation into Irish historical ceramics: the brick of Arch Hall, Wilkinstown, Co. Meath

Abstract

A letter written in 1710 by Robert, first Viscount Molesworth, to his wife describes ongoing work to the garden of their estate in Co. Dublin and to the digging of ponds and the subsequent making of bricks. This connection between the formation of designed landscape and the production of brick for building purposes has prompted the following scientific investigation. The paper applies physical science to the study of eighteenth-century Irish brick in order to gather information about its provenance and the source of its constituent materials. Analytical techniques were employed to study the bricks used to build Arch Hall, a mansion house dating from the first half of the eighteenth century with an extensive demesne in Co. Meath. Clay samples were collected from the demesne, fired in the laboratory and analysed for comparative purposes. The results indicate that the bricks are hand-made with silica- based, predominantly non-calcareous clay of glacio-fluvial origin. Firing temperatures ranging between 700ºC and 1000ºC were deduced based on mineralogical and colour changes during firing. The colour of both the original brick and the fired samples is consistently orange-red. This is due to the presence of dispersed hematite formed during firing in an oxidising atmosphere from the iron-bearing minerals in the clay. The petrography of the pointing mortar was used as an additional resource to gather evidence for provenance. The brick temper and mortar aggregate are consistent with each other and with the geology of the area, suggesting a local source for both the brick-making sediment and the mortar aggregate.