Pottery firing temperatures: a new method for determining the firing temperature of ceramics and burnt clay

Abstract

a b s t r a c tA new method for determining the maximum firing temperature of ceramics and burnt clay is presented. The technique relies on measuring the magnetic susceptibility on a step-wise re-fired sample. The validity of the method has been tested by determining firing temperatures of two sets of clay samples fired at temperatures ranging from 400 to 1000 C. Aliquots of the same samples have been studied petrographically by optical microscopy on thin sections and analyzed by powder X-ray diffraction in order to monitor structural and mineralogical changes as a function of temperature. The method is demonstrated on samples from four geographically widely different sites and it is applied to a larger set of ceramics of Late (ca. AD 900eAD 1450) and Inca (ca. AD 1480eAD 1532) periods from the Northwestern Argentine region, dating to a limited period of time prior to the fall of the Inca Empire. The method is shown to be a powerful tool in revealing archaeological information about the change in firing technologies in the pre-Hispanic societies in the Andean area through time.

A Mineral Magnetic Approach to Determine Paleo‐Firing Temperatures in the Neolithic Settlement Site of Mursalevo‐Deveboaz (SW Bulgaria)

“…The ancient firing temperatures at the Neolithic site of Mursalevo‐Deveboaz estimated using the magnetic susceptibility method (Rasmussen et al, ) provide ample proof of intense fires involving the majority of the houses, since the lowest firing temperatures exceed 700°C (Figures a and b). As is also evident from Figures a and b, the temperatures obtained are clearly linked to the burned daub's color, which in turn is mainly governed by the iron oxide phase (Murad & Wagner, ).…”

“…In this way, the magnetic susceptibility reflects the change in the mineralogy which is often accompanied by changes in the material's porosity during heating (Wagner et al, ). Determination of ancient firing temperature using magnetic susceptibility (Rasmussen et al, ) was applied to a collection of 148 samples collected from 25 houses at the settlement site. Samples were selected to represent different visual color and texture.…”

Clay source and firing temperatures of Roman ceramics: A case study from Plovdiv, Bulgaria

“…Similarly to mineralogical and chemical composition, magnetic properties of archaeological ceramics and other burnt clay materials are suitable for their characterization, for example, evaluation of the technological conditions applied during their production (maximum heating temperature; Linford & Platzman, ; Rasmussen, De La Fuente, Bond, Mathiesen, & Vera, ; Salaoru, Matau, Tascu, Curecheriu, & Stancu, ), atmosphere (Maritan, Nodari, Mazzoli, Milano, & Russo, ), heating and cooling rate (Genevey & Gallet, ), and duration of firing (Maggetti, Neururer, & Ramseyer, ), as well as distinguishing groups of sherds having different provenance (Beatrice, Coïsson, Ferrara, & Olivetti, ; Rasmussen, ). Magnetic susceptibility in particular is helpful in revealing different aspects of ancient pottery technology and provenance (Karacic, Jameson, & Weil, ; Rasmussen et al, ; Velraj, Musthafa, Janaki, Deenadayalan, & Basavaiah, ).…”

Effect of heating rate on gas emissions and properties of fired clay bricks and fired clay bricks incorporated with cigarette butts

“…Attempts have been made to investigate the volumes of gases released at different temperatures and their correlations with the clay properties; see for example the studies by Parsons et al (1997), Santos et al (2003) and Toledo et al (2004). In particular, Dunham et al (2001) and Rasmussen et al (2012) investigated shorter firing times in the manufacturing of clay bricks while Dondi et al (1999) compared the influences of fast firing and traditional firing on physical and mechanical properties of clay bricks. Gonzalez et al (2002), Cusido et al (2003), Gonzalez et al (2006), Gonzalez et al (2011) and Shen et al (2013) emphasised the reduction of gas emissions, specifically of fluorine, chlorine and sulphur, by controlling the firing temperature and mineral contents of the clay during the manufacturing process.…”