Extremely Thin Gold Layers on Gilded Silver Threads

Abstract

More than 350 gilded metal embroidery threads from old textiles in Swedish collections have been examined, measured, and chemically analysed. There are no significant differences in geometrical dimensions over the centuries (1400–1900) for this material. The wound metal strips usually have a width around 0·2–0·6mm and a total thickness of 0·01–0·05mm, while the gold wire diameters are 0·05–0·45mm. A rapid method has been developed to make a rough estimate of the thickness of thin gold layers by scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM/EDS) and correction curves obtained with a series of gold-sputtered silver standards. The results indicate that the gold layers are extremely thin, usually <1 μm and often <0·1 μm. This implies that gold concentrations reported in older publications are often too low. It is important to know the gold layer thickness before conservation is undertaken. The paper concludes by summarizing the results of statistical multivariate analysis with relevant data for the gilded threads.