Regensburg 2016 – wissenschaftliches Programm

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MI: Fachverband Mikrosonden

MI 7: Poster: Microanalysis and Microscopy

MI 7.1: Poster

Mittwoch, 9. März 2016, 18:00–20:00, Poster E

Micro-XRF studies on the colour brilliance in ancient wool carpets — •Andreas Späth¹, Markus Meyer¹, Camelia Borca², Karl Meßlinger³, Manfred Bieber⁴, and Rainer H. Fink¹ — ¹FAU Erlangen-Nürnberg, Physical Chemistry II & Interdisciplinary Center for Molecular Materials (ICMM), Erlangen, Germany — ²Swiss Light Source (SLS), Paul Scherrer Institute, Villigen, Switzerland — ³FAU Erlangen-Nürnberg, Physiology and Pathophysiology, Erlangen, Germany — ⁴Ex Oriente, Waldbrunn, Germany

Chemical colouring of natural fibers is one of the oldest crafts in mankind and still a highly relevant market. Experimental archaeologists revived an ancient Anatolian dyeing method based on previous fermentation of the wool fibers resulting in remarkable colour brilliance and persistence. Mordants used during the bating process are typically potassium alum or iron(II)sulfate. Electron microscopic studies show morphological changes of the fibers due to fermentation, suggesting an easier and deeper penetration of mordants into the hair fiber. We present micro-XRF studies on cross-sections of such prepared recent wool fibers and regional carpet fibers from the 18th century showing the distribution of mordant metals. A comparison with undyed fibers proves a significantly increased metal content also in the central region of the recently fermented and ancient wool fibers. These findings provide a conclusive explanation for persistent colour brilliance and prove the suggested crafting of the ancient specimen. Further studies focus on the oxidation state of the Fe mordant to clarify the typically strong modification of dye colour that is not apparent for redox-inactive Al.