We are pleased to announce a new, online edition of the NICAS colloquium on Thursday 26 September 2024 from 12.00 to 13.00 hrs. The colloquium will take place online through Microsoft Teams.
Throughout the year, NICAS organises a bi-weekly Colloquium consisting of two short research lectures. It provides researchers with the opportunity to present ideas for, updates on or results of their activities. The NICAS Colloquium allows people to stay informed on a regular basis about the latest developments and results of research and to exchange information and expertise.
The presenters are Joen Hermans (University of Amsterdam) and Yueer Li (TU Delft)
The chair is Benjamin Rous
► Joen Hermans – Watching oil dry: Comprehensive characterization of drying oil oxidation and polymerization
Abstract:
Many issues in the conservation of oil paint lead towards a very challenging central question: what is the molecular structure of an aged oil binder? In this context, it is important to understand how factors like paint composition and curing conditions affect the chemistry and network structure of the oil binder, and subsequently the links between the structure and long-term paint stability. In our journey to answer these questions, we employed time-resolved ATR-FTIR spectroscopy and comprehensive data analysis to study the curing behavior of five types of drying oil and the effects of curing temperature as well as the presence of a curing catalyst (PbO). This approach yielded a very detailed insight into the changing chemistry of oils during drying. Analysis of reaction rates suggested that PbO induces a network structure with a more heterogeneous cross-link density, and the ATR-FTIR spectra indicate lower levels of oxidation in those cases. Finally, lower temperatures appear to favor the formation of more carboxylic acid groups in oil mixtures with PbO.
Bio:
Joen Hermans is Assistant Professor Conservation Science, a joint position between the Conservation & Restoration program and the Van ‘t Hoff Institute for Molecular Sciences, both at the University of Amsterdam. Since 2017, he has held an additional position as researcher at the Conservation & Science department of the Rijksmuseum. He obtained his PhD on metal soap formation in oil paint under supervision of Piet Iedema and Katrien Keune at the University of Amsterdam in 2017. Between 2018-2022, he worked on a NWO/Veni project studying the influence of water on oil paint chemistry.
► Yueer Li – “data-fusing” gamma spectroscopy with neutron tomography for non-invasive elemental analysis of bronze artifacts
Abstract:
A significant challenge in researching bronze artefacts is determining their elemental composition non-invasively. The most common technique used in museums, XRF, only detects signal from surface due to its limited penetration depth. Unlike X-rays, neutrons can penetrate bulk metals, making neutron-based methods the only possible approach to non-destructively access the interior of metal sculptures. Neutron tomography (NT) exploits this capability to reveal structures and is increasingly popular in bronze research, but the unavoidable gamma radiation induced by neutrons is traditionally seen as a drawback. However, this temporary radiation contains valuable elemental information that can be extracted “for free”. Based on this, I developed a ray-tracing simulation based method that combines gamma spectroscopy (GS) with NT, enabling both geometry and elemental composition of the interior of bronzes to be determined from a single NT experiment. In this presentation I will show the concept behind the data fusion and how it allows to obtain quantitative elemental information from two semi-quantitative experimental techniques.
Bio:
Yueer Li is a fourth-year PhD candidate in the Neutron & Positron Methods for Materials group (NPM2) of Delft University of Technology (TU Delft) under the supervision of Dr. Lambert van Eijck. She is involved in the NICAS “Beeldvorming” project, which focuses on developing neutron-based approach to look inside cultural heritage objects in a non-invasive manner.