New research involving the University of Ljubljana, including the Heritage Science Laboratory Ljubljana and the Centre of Excellence Green Heritage Science provides new insights into the degradation of historical silk and offers a new modelling approach to support its sustainable preservation in museum collections.
The study, Damage function for silk fabric, published in npj Heritage Science on 6 June 2026, brings together researchers from the University of Ljubljana, University of Glasgow and University of Antwerp. The authors are Ibrahim Elrefaey, Hend Mahgoub and Matija Strlič from the University of Ljubljana, Paul Garside from the University of Glasgow, and Natalia Ortega Saez from the University of Antwerp.
Silk is an important part of many cultural heritage collections, but its long-term preservation presents significant challenges. In particular, silk produced in the 19th and early 20th centuries was sometimes treated with tin-phosphate salts to increase its weight. The effects of this historical practice on the subsequent degradation of silk have remained insufficiently understood.
The researchers investigated how tin-phosphate weighting affects the chemistry and degradation of silk. Their experiments demonstrate that weighting increases the pH of silk and makes it chemically more stable, but does not fundamentally change the mechanism of degradation, which remains dominated by hydrolysis.
A key outcome of the research is the development of damage functions for silk. These models relate environmental conditions to the rate at which silk deteriorates. The researchers developed isoperms and isochrones, including uncertainty intervals calculated using Monte Carlo simulations. The damage threshold was established through fold and needle tests carried out by experienced textile conservators.
The study is notable for the breadth of expertise and heritage institutions contributing to the research. Textile conservators Ana Motnikar (Slovene Ethnographic Museum), Ana Serrano (University of Amsterdam), Elizabeth Anne Haldane (Victoria and Albert Museum), Eva Ilec (Regional Museum Ptuj–Ormož), Kim Verkens (Fashion Museum Antwerp), Marjolein Koek (Rijksmuseum), and Silvia Zechmeister-Mittermaier (Professional Association of Austrian Conservators, ÖRV) contributed to the practical assessment of silk through fold and needle testing. The research also benefited from access to historical collections and scientific instrumentation. Irena Porekar Kacafura of the Maribor Regional Museum provided access to a historical silk collection.
The results have direct implications for the preventive conservation of textile collections. The models show that acidic silk is particularly vulnerable to degradation and requires colder and drier storage environments. This provides conservators and collection managers with a quantitative basis for assessing environmental risks and making decisions about the storage of vulnerable silk objects.
The work forms part of the SAFESILK project, funded by the Slovenian Research and Innovation Agency (ARIS) and the Research Foundation Flanders (FWO). The project brings together heritage scientists, conservation specialists and heritage institutions to understand, prevent and treat metal salt-induced degradation of historical silk. The wider SAFESILK collaboration includes the ARCHES (AntweRp Cultural HEritage Sciences) research group at the University of Antwerp, the Heritage Science Laboratory Ljubljana at the University of Ljubljana, MoMu – Fashion Museum Antwerp, and the National Museum of Slovenia.
By providing a scientifically validated way of assessing silk degradation, the research contributes to more evidence-based approaches to preventive conservation and supports the development of sustainable strategies for the long-term preservation of textile heritage.
