CRAFTER: An Experimental Approach to Fire-Induced Alteration of Pottery Fabrics

Abstract

In doing an inventory of ceramic materials from archaeological excavations, it is a common practice to indicate their observable atmosphere of firing. This parameter refers to the presence of gases, especially oxygen, during the firing and cooling of pottery: if oxygen circulates freely, the procedure is said to be oxidising; if, on the contrary, the atmosphere of firing lacks free air, it is called reducing (Rice 1987: 81). The atmosphere of firing affects the physical properties of finished pottery, including hardness, porosity and shrinkage, but most visibly colour (Rice 1987: 81). Nevertheless, the colour range of fabrics does not depend only on firing conditions, but also on the iron content of the clay and its distribution within it (Orton, C. et al. 1993: 69). In any case, the firing atmosphere of a piece of pottery can be classified as oxidising, reducing or alternating when inventorying. In principle, this should facilitate the task of reassembling broken archaeological objects and, as a consequence, their study as a whole. Recognising and classifying fragments based on similar physical properties, such as thickness, temper, fabric colours, etc., is an essential step toward determining which belong to the same individual object. However, this criterion can sometimes be misguiding, especially concerning colour.

Keywords

• ceramics
• technique
• colour
• bronze age
• spain