THE USE OF IMAGE ANALYSIS TO DETERMINE YARN TWIST LEVEL IN ARCHAEOLOGICAL TEXTILES

An analysis of the structure of archaeological textiles can give an insight into different traditions, geographic origins or technologies associated with the textile production. An important parameter in this context is the level and direction of yarn twist. In this paper a new quantitative method of yarn twist measurement is described. Using image analysis techniques a measure of the mean twist level and the variation in twist can be determined. The technique is applied to a selection of woven woollen textiles from the first-century Roman fort at Vindolanda in northern England.     

AN EXPLORATION OF PREHISTORIC SPINNING TECHNOLOGY: SPINNING EFFICIENCY AND TECHNOLOGY TRANSITION*

Thigh‐spinning and spindle‐spinning, methods for making yarn and string, have been used through the millennia to produce substantial quantities of yarn for textiles. Productivity data were gathered in a replication study of thigh‐spun and spindle‐spun yarns and were recompiled from the literature. Calculated production rates allow comparison of the spinning methods. Factors influencing production rate include intrinsic fibre properties, fibre preparation and particular details of spinning technique, as well as the experience and motivation of the spinner. The role of efficiency in technology transition between thigh‐spinning and spindle‐spinning is discussed.     

INVESTIGATION OF THE COLOURING MATERIALS OF FUSTAT CARPET FRAGMENTS

The Benaki Museum (Athens, Greece) possesses 50 fragments that, according to its archives, are recorded as having a provenance in the Fustat area. The objects are divided into three groups on the basis of the techniques employed. Most (eight) of the objects included in the present study belong to group A (8th–11th centuries). A few (five) fragments belong to groups B and C, which include objects dated up to the 18th century. The goal is to identify the colouring compounds contained in microsamples removed from the selected Fustat carpet fragments. Identifications are achieved using high‐performance liquid chromatography (HPLC) with photodiode array detection (PDA). The following compounds are identified repeatedly in many samples: laccaic acid A and other laccaic acids (components of Kerria lacca, Kerr), alizarin, purpurin and rubiadin (madder components), luteolin, apigenin and chrysoeriol (components of Reseda luteola L.), and indigotin and indirubin (components of indigoid dyes). In one sample, the type C compound (marker compound for the identification of soluble redwoods, Caesalpinia trees) is identified. The HPLC profiles collected for the samples in which madder components are detected suggest that most probably Rubia tinctorum L. (and not Rubia peregrina L.) was used during dyeing.     

THE ANALYSIS OF DYESTUFFS FROM FIRST‐ TO SECOND‐CENTURY TEXTILE ARTEFACTS FOUND IN THE MARTRES‐DE‐VEYRE (FRANCE) EXCAVATIONS*

A series of Gallo‐Roman clothes and miscellaneous textile fragments from the first and second centuries from the Martres‐de‐Veyre necropolis (Puy‐de‐Dôme, France) was investigated. The objects studied were excavated between 1851 and 1923, during successive rounds of archaeological work. Since that time, they have been conserved in the Barguin Museum at Clermont‐Ferrand. The target of our research was dye identification, as it gives very interesting and useful information regarding the ancient technology. This approach has until now not been considered to be relevant and, unfortunately, is not systematic. The analysis was carried out by high‐performance liquid chromatography with photodiode array detection (HPLC–PDA). The small samples (threads up to 0.6 mg, less than 1 cm long) of coloured textile fibres were submitted to this technique. In one case, X‐ray fluorescence (XRF) analysis was applied. According to the analysis, the dyeing sources proposed are the Rubiaceae family for red, a luteolin ‘base’ for yellow, ellagitannins for brown and indigo for blue colours. Several samples did not seem to contain any dye. We point out possible factors for the partial dye source determination: instrumental limits, sample size, low dyestuff content in analysed samples and the dyes’ decomposition during ageing. Some improvements of dye analysis in archaeological samples by separation techniques based on recent analytical instrumentation and combined approaches are proposed.     

Adhesive Production and Pottery Function During the Iron Age at the Site of Grand Aunay (Sarthe,France)*

A combination of elemental, functional and molecular analyses performed on amorphous organic residues dating from the Iron Age was developed in order to identify these remains and to understand their relationship with ceramic vessels in which some of them were found. These analyses made it possible to distinguish between ceramic vessels used for the production or storage of adhesive materials, mainly birch bark tar, and those dedicated to the preparation of culinary commodities, which contained animal fats. The organization of the production of adhesives is described and the addition of beeswax to birch bark tar is reported for the first time. The use of birch bark tar for coating ceramic vessels is also discussed.