Heritage Science Laboratory Ljubljana

Daša Terobšič

Various metals originating from catalyst residues, stabilizers and some additives such as flame retardants, antimicrobial reagents, plasticizers and pigments can be found in synthetic fibers and plastic materials of everyday use. Excessive concentrations of these metals can adversely affect the properties of such materials, so the quantitative determination of metals is important for the identification of impurities, for the assessment of the quality of polymer production, and also from the point of view of understanding the effect of metals on the durability of the material. In the case of poly(vinyl chloride), during the decomposition of the polymer, organometallic compounds, metal oxides or carbonates, which are added as stabilizers, react with the resulting hydrochloric acid, which is eliminated from the polymer chain, and thus prevent decomposition. In my master’s research, I optimized the microwave decomposition of PVC and subsequently determined the metals in the resulting solution using ICP-OES. I checked the results for some samples using SEM-EDS. The goal of the master’s research is primarily to find meaningful connections between the presence of various metals and the properties of PVC and to determine how these metals affect the durability of the material.

Tomaž Mržljak

Historic artifacts are a vital part of our cultural heritage, so they need to be protected from substances that could harm them – the ones in museums are particularly endangered, especially if the buildings are not (well-)ventilated. The project focuses on characterization of sorbents that could be suitable for the protection of artifacts by absorbing harmful compounds, which would otherwise degrade (decompose) them. First, a general test of sorbents is done with the Oddy test, where we can superficially assess whether the sorbent is suitable to be placed near the artifacts, as it could also emit harmful compounds. Sorbent analysis is continued by SPME sampling. Identification of the resulting compounds is done by GC / MS.

Supervisor: Irena Kralj Cigić

Ana Šiško

Copper-based green pigments promote the deterioration of many valuable historical manuscripts. Verdigris was often used, from antiquity to the 19th century, as a green or green-blue pigment. Despite the fact that it is very unstable, as the color changes with time and depending on atmospheric conditions, it was widely used for manual coloring of printed material, as it is semi-transparent and does not cover the printing ink. It was mainly used on illuminations, book illustrations and maps.

The aim of the project is to study the degradation of different papers with the application of verdigris pigment under the conditions of thermal accelerated degradation, which is comparable to the natural degradation. Model samples will be analysed by AAS, SEC, FTIR and colorimetry. The influence of two antioxidants on the stability of verdigris paper will also be evaluated under the same conditions and with the same methods. Part of the samples will be treated with tetrabutylammonium bromide, which has an antioxidant effect in the pseudo-Fenton reaction system on verdigris paper. The second part will be treated with 1H-benzotriazole (BTA), which has also been shown to slow down the degradation of verdigris paper, but the research was conducted under thermally accelerated degradation conditions that are not comparable to natural pigment degradation processes.

Maja Šubic

Plastic objects and art from 19^th century and later, which are stored in museums and galleries, undergo visible change in the time they are kept there. This presents a problem for the institutions, as in how to store them so they remain in their original state. One of the processes that occur is migration and subsequently loss of PVC plasticizers. The aim of this work will be to obtain the information about how the type of phthalate plasticizer, moisture, airflow and air temperature affect migration and content of plasticizers in PVC. The techniques which will be used are GC-FID and FT-IR. The results of this projects will be helpful in creating guidelines for preservation of plastic heritage  objects and art [COBISS.SI-ID 108508675].

Supervisor: Matija Strlič

Sara Moreno Castaño

Many extraordinary examples and illustrations of coloured paper from the islamic medieval era have been preserved in heritage institutions around the world. In this research, 17 islamic samples from 18^th to 19^th centuries are analyzed to detect some natural dyes.

The techniques used are related to Raman spectroscopy such as conventional Raman, portable Raman and surface-enhanced Raman spectroscopy (SERS). Using these techniques, a dye spectral reference database of the most used dyes in the Islamic era (henna, madder, weld, saffron, safflower, lac and curcuma) is built and used as a reference when analyzing the historic islamic samples. In islamic coloured paper can be present direct dyes or mordant dyes, thus some pretreatment prior analysis of Raman spectroscopy (using techniques such as the hydrolysis with hydrofluoric acid) are tested on dyed reference paper to find the one that best extracts the dye from the paper.

The research will contribute to achieve a better knowledge about the composition of the islamic paper and the dyes on it, as well as knowledge about how to preserve and handle this historical paper.