Until recently, applications of spectral imaging in heritage science mostly focused on qualitative examination of artworks. This is partly due to the complexity of artworks and partly due to the lack of appropriate standard materials. With the recent advance of NIR imaging spectrometers, the interval 1000–2500 nm became available for exploration, enabling us to extract quantitative chemical information from artworks. In this contribution, the development of 2D NIR quantitative chemical maps of heritage objects is discussed along with presentation of the first quantitative image. Further case studies include semiquantitative mapping of plasticiser distribution in a plastic object and identification of historic plastic materials. In the NIR imaging studies discussed, sets of 256 spatially registered images were collected at different wavelengths in the NIR region of 1000–2500 nm. The data was analyzed as a spectral cube, both as a stack of wavelength-resolved images and as a series of spectra, one per each sample pixel, using multivariate analysis. This approach is only possible using well-characterized reference sample collections, as quantitative imaging applications need to be developed, thus enabling spatial maps of damaged and degraded areas to be visualized to a level of chemical detail previously not possible. Such quantitative chemical mapping of vulnerable areas of heritage objects is invaluable, as it enables damage to historic objects to be quantitatively visualized. The results of this work was published in the distinguished journal Analytical Chemistry (Washington), and two of the authors (L.C. and M.S.) acquired basic knowledge on the paper chemistry in our research group. They perform now the research on this subject in the Centre of Sustainable Heritage, The Bartlet School of Graduate Studies, University College London.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 35488773We investigated the shrinkage temperature of collagen and the influence of lipids contained in parchment on the measurements. Lipids content does not significantly affect shrinkage temperature measurements, but it strongly affects the decrease of shrinkage temperature of collagen during degradation. This confirms the high importance of lipid peroxidation during degradation of parchment. While shrinkage temperature determination is a microdestructive method, we also demonstrated that it is possible to determine this property using NIR spectroscopy and further also non-destructive dating of historic parchment.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 34838533A novel setup is described in which we combined the separation of a volatile substance from a sample with a complex matrix on the basis of a microdiffusion process with a kinetic on-line spectrometric monitoring of the reaction in the receptive medium at 365 nm. The fruit juice was selected as a model for testing the performance of the setup in real-life applications.
F.06 Development of a new product
COBISS.SI-ID: 35545605