An approach to analysis of advanced sensor materials based on cobalt oxide modified with zinc or nickel oxides is developed using X-ray fluorescence analysis (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). It is shown that determination of Ni, Zn, and Co in novel materials based on cobalt oxide using ICP-MS in solutions is possible, the standard deviation being 0.06, 0.06, and 0.05, respectively. The results of the ICP-MS determination of the elements in solutions are used to certify the results obtained by the XRF method without sample preparation. It is shown that Ni_xCo_{3 –x}O_{4 – δ} samples can be correctly analyzed without decomposition using X-ray fluorescence analysis. The results of the determination match theoretically calculated values for the samples obtained both from nitrates and from oxalates of nickel and cobalt. However, calibration based on the ICP-MS results is necessary for X-ray fluorescence analysis of Zn_xCo_{3 –x}O₄ samples. It is shown that the zinc content in the samples exceeds the theoretical determined value by 10–30% because of incomplete precipitation of cobalt from the solution upon synthesis.

Treating silk with metal salts was a common practice starting in the second half of the 19th century until the early 20th century. It aimed to increase the weight and thickness of the fibres. However, the presence of metal salts is believed to accelerate and aggravate the deterioration of historical silk textiles, and weighted silks are nowadays considered one of the most pressing issues in textile conservation. This paper explores the history of the practice of metal salt weighting of silk: the materials and methods used, the reasons behind weighting, and how this practice developed as the product of a specific historical and economic context. A total of 147 primary textual sources (patents, dyers’ manuals, and books) were investigated and from these 136 weighting methods were collected and reviewed. The results highlighted tin salts as the most commonly mentioned metal salts for weighting silks of any colour. Iron compounds combined with tannins were the method of choice for dark silks, although also in combination with tin in half of the cases. The knowledge gained from this research will help further the study of the degradation pathways of historical silk fabrics, as representative reproductions of weighted silks will be produced based on the findings.

Prized for its lustrous sheen, remarkable tensile strength, and unrivalled affinity to a wide range of dyes, silk has served for millennia as a prestige material across Eurasia and beyond, making it one of the most culturally charged textiles to survive into heritage collections today. In 19th- and 20th-century Europe and North America, silk was often immersed in baths of inorganic salt solutions to increase its weight and drapeability. The presence of these so-called “weighted” silks and their state of preservation within cultural heritage collections remain unclear, as they are difficult to identify with the naked eye. Yet it is well known that fabrics from this period are prone to rapid, often sudden, deterioration. This research examines silk weighting practices at a theoretical, macro- and micro-level; understanding them is essential for deciding how best to preserve and display historical fabrics. The work began with a study of the technological processes used to weight silk during that period, based on historical sources. Knowing the methods and ingredients applied to silks made it possible to choose the appropriate analytical techniques to investigate them. The focus then shifted to identifying weighted silks in museum collections. A methodology based on portable X-ray fluorescence spectroscopy was developed and refined by introducing a beamstop, an X-ray-absorbing layer placed behind the fabric, which enabled precise, layer-selective analyses. Historical silk fabrics from garments, accessories and upholstery in Belgian and Dutch museum collections were analysed on site, quickly and without causing damage. For the first time, a systematic survey revealed a link between weighting and the state of preservation of the fabrics. Samples of the most damaged fabrics were then analysed in detail, down to individual threads and fibres. Techniques such as Fourier-transform infrared spectroscopy, X-ray fluorescence spectroscopy and X-ray diffraction revealed differences in weighting and degradation between thread systems, as well as within individual fibres. The focused X-ray beam generated by synchrotron radiation made it possible to study individual fibres and their cross-sections at high spatial resolution, revealing the distribution of the weighting agents and the state of degradation of the silk. By combining knowledge from multiple disciplines, this thesis deepens our fundamental understanding of the degradation processes caused by metal salts that threaten historic silk textiles worldwide. The findings will contribute to the optimisation of collection management and the prioritisation of conservation interventions, as well as to an understanding of the prevalence of weighted silk in collections and its ongoing salt-induced deterioration.