Spectroscopic analysis used to uncover the original paint colour of the Helsinki Government Palace tower clock faces

The paint stratigraphy of the two clock faces from the tower clock of the Government Palace in Helsinki (Finland) was analysed in order to determine their original colour before restoration works. Paint cross-section samples from both clock faces were analysed by confocal Raman microscopy and scanning electron microscopy coupled to an energy dispersive X-ray spectrometer (SEM-EDS). The results revealed the complex superimposition of paint layers applied over the original black colour. FTIR/ATR analyses proved that the original paint was prepared with linseed oil-resin media. Most likely not all of the different layer colours were visible. Some of the layers were likely to have been a primer or for rust protection.Peer reviewe

Multianalytical Approach to explain the darkening process of hematite pigment in paintings from ancient Pompeii after accelerated weathering experiments

[EN] In this paper, recently excavated fresco painting fragments from the House of Marcus Lucretius (Pompeii) and not exposed to the atmosphere since the eruption of the Mount Vesuvius were subjected to a controlled SO2 atmosphere and high relative humidity. These experiments were conducted in order to simulate under accelerated conditions the possible deterioration of the hematite pigment and plaster. The mineralogical transformation of the polychromy and plaster was monitored using mainly Raman spectroscopy, a non-destructive technique, but also infrared spectroscopy (FT-IR) and scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDS). After different exposure cycles to SO2, it was confirmed that hematite red pigment (Fe2O3) can be reduced into magnetite (Fe3O4), which provides the darkened colour to the pigment. While Fe(III) from hematite is reduced into Fe(II) or mixed Fe(III) and Fe(II), the SO2 can be oxidized (SO3) and hydrated to experience a subsequent wet deposition (H2SO4 aerosol) causing also the transformation of calcite into gypsum. Finally, it was assessed that high concentrations of SO2 can also cause the sulphation of hematite pigment promoting its transformation into paracoquimbite/coquimbite (Fe2(SO4)3$9H2O). Moreover, in some areas of the deteriorated painting fragments, non-expected iron(II) sulphate and sulphite species were also identified

Kulttuurihistoriallisten materiaalien menneisyys ja tulevaisuus : konservoinnin materiaalitutkimuksen heritologiset funktiot

The dissertation deals with the heritological functions of materials research of conservation. It is based on seven materials research publications by Ulla Knuutinen. The titles of the publications are: - Report of the Pompeii Project/ Project Report of Pigment Analyses of the Fourth Style Wall Paintings In the Casa Di Marco Lucrezio (IX 3, 5.24) in Pompeii - Colours and Inorganic Pigments of the House of Marcus Lucretius (Insula IX 3, 5/24) - Cadmium Colours: Composition and Properties - Two Case Studies of Unsaturated Polyester Composite Art Objects - Leather Spue: A Problem with Lubricants - Wax Analyses in Conservation Objects by Solubility Studies, FTIR and DSC - Contra! of Aqueous Paper Treatments with Ion Chromatography The publications belong to the natural sciences. The cultural historic material groups which are included in the publications are the following: inorganic pigments from organic binding media waxes and modem composite materials combined with fibre glass. In addition, paper cellulose is also included as a traditional organic fibre material. The dissertation creates a connection between materials research of conservation and heritology. It offers proof of the fact that materials research of conservation is a part of multidisciplinary heritology and that materials research focusing on cultural historical objects has an important role in preserving cultural heritage. The dissertation presents different functions of materials research of conservation. If reliable information for the documentation is needed on materials of the object, on the origin of the object, on the authenticity of the object, or on the fact as to whether any restoration has been made previously, analyses that reveal chemical compositions must be performed. On the other hand, materials research can be focused on examining ageing properties of materials to find out the chemical and physical changes caused by different environmental conditions. This type of research benefits the preservation of cultural heritage objects, because results can be applied to planning and implementation of both preventive and active conservation. Furthermore, material research is needed for testing and examining conservation and restoration methods

Materials research in conservation and heritology

This article is based on the dissertation by the author. It creates a connection between materials research and conservation and heritology. Materials research is a part of multidisciplinary heritology and it has an important role in preserving cultural heritage. If reliable information for the documentation is needed about the materials in an object, on the origin of the object, on the authenticity of the object or on whether any restoration has been carried out previously, analyses that reveal chemical compositions must be performed. On the other hand, the materials research can be focused on examining the ageing properties of materials to find out the chemical and physical changes caused by different environmental conditions. This kind of research benefits the preservation of cultural heritage objects, because results can be applied to both preventive and active conservation. Furthermore, materials research is needed for testing and examining the conservation and restoration methods.

A Chance for daydreaming; Conservation-restoration and technical research of an outdoor UPR plastics installation from 1992

Peer reviewe

Multispectroscopic and isotopic ratio analysis to characterize the inorganic binder used on pompeian pink and purple late pigments

International audienc

Exercise of Rights Resulting from Drafts and Notes

Because of the fact that pigments are not ubiquitous in the archeological record, the application of noninvasive analytical methods is a necessity. In this work, pink and purple lake pigments recovered from the excavations of the ancient city of Pompeii (Campania, Italy) and preserved in their original bowls at the Naples National Archaeological Museum (Italy) were analyzed to characterize the composition of their inorganic binders (mordants). In situ preliminary analyses using a hand-held energy dispersive X-ray fluorescence spectrometer (HH-ED-XRF) allowed us to determine the use of an aluminosilicate enriched in Cu and Pb. Scanning electron microscopy coupled to energy dispersive X-ray spectrometry (SEM-EDS) and benchtop ED-XRF analyses confirmed these results, while inductively coupled plasma mass spectrometry (ICPMS) allowed one to determine the concentration of major, minor, and trace elements. The use of other techniques such as X-ray diffraction (XRD), and micro-Raman and infrared spectroscopies allowed one to characterize the pigments at the molecular level. The high concentration of Cu detected in the pigments (1228–12937 μg g–1) could be related to the addition of Cu salts to obtain the desired final hue. The concentrations of Pb (987–2083 μg g–1) was also remarkable. Lead isotopic ratio analysis (206Pb/207Pb) suggested a possible origin related to the leaching of the ancient lead pipes from Pompeii and the subsequent transfer to the buried pigments or to the inorganic binder. Molecular analysis also showed that the binder is composed of an allophane-like clay. Moreover, it was possible to determine that to obtain the final purple hue of a specific pigment, Pompeian blue pigment was also mixed into the dyed clay.The authors would like to thank the Naples National Archaeological Museum for the permissions given to perform the in situ measurements of the raw lake pigments contained in the original bowls and deposited in this museum and also for the permissions given to extract samples from these pigment bowls. This work has been funded by the Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (FEDER) through the Project DISILICA-1930 (ref BIA2014-59124-P). Iker Marcaida is grateful to the Basque Government who funded his predoctoral fellowship. Technical support provided by the General X-ray Service of the SGIKer (UPV/EHU, MICINN, GV/EJ, ERDF, and ESF) for the X-ray diffraction analyses and also by the Raman-LASPEA Laboratory of the SGIker (UPV/EHU, MICINN, GV/EJ, ERDF, and ESF) is also gratefully acknowledged