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6 - Structure and Chemical Composition of the Surface Layers in the Amsterdam Sunflowers
- Edited by Muriel Geldof, Maarten van Bommel, Marije Vellekoop, Ella Hendriks
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- Book:
- Van Gogh's Sunflowers Illuminated
- Published by:
- Amsterdam University Press
- Published online:
- 25 November 2020
- Print publication:
- 21 June 2019, pp 159-174
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Summary
Introduction
Since its completion by Vincent van Gogh, the Amsterdam Sunflowers has been the subject of a complex history of interventions. Combined with the natural ageing and deterioration of the materials used by the artist, this has strongly affected the present appearance of the painting. The materials and techniques used in Sunflowers and related colour changes have been presented in chapters 4 and 5. This chapter focuses on characterizing the non-original surface layers present as well as secondary compounds arising from pigment-binder interaction in original paint components. The outcomes of this research help to reconstruct the restoration history of the painting and to understand its present condition, as a basis for optimizing future conservation treatment (as elaborated in chapter 7).
In keeping with Van Gogh's usual practice in the period, he left Sunflowers in an unvarnished state. Today, however, multiple layers of varnish are present. These have yellowed and make the painting appear highly glossy, whereas originally it presumably had the more subtle satin gloss related to pure oil paint. Conversely, some areas of the painting now look matt, since wax has been locally applied in the past.
Historical records provide sparse information regarding the surface layers added during earlier campaigns of treatment (see chapter 7). We know that the painting was varnished in 1927 by the conservator Jan Cornelis Traas, as part of a broader restoration and structural (lining) treatment. Remains of paper tape on the tacking margins of the painting are believed to date from this period (see chapter 7, p. 184). Further documents record that in 1961, Traas worked on the painting again. However, as there is no known account of what this treatment entailed, it remained in question whether Traas removed the 1927 varnish and/or applied new surface coating layers instead. Furthermore, in the late twentieth century, wax was applied in certain areas, used to matt down the glossy varnish and/or impregnate and consolidate the ground.
This chapter describes the outcome of the technical examinations of the Amsterdam Sunflowers, characterizing the surface layers present and assessing the history of application as revealed by their stratigraphy and chemical composition.
8 - Methods and Techniques: Optical Coherence Tomography (OCT)
- Edited by Muriel Geldof, Maarten van Bommel, Marije Vellekoop, Ella Hendriks
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- Book:
- Van Gogh's Sunflowers Illuminated
- Published by:
- Amsterdam University Press
- Published online:
- 25 November 2020
- Print publication:
- 21 June 2019, pp 207-227
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Summary
Optical coherence tomography (OCT) is an imaging technique offering a non-invasive alternative to the traditional analysis of artworks by means of sampling. A cross-section photomicrograph of a sample collected from a painting has its own limitations, mostly due to the restricted number of samples it is possible to collect. There is a need, therefore, for non-invasive verification of locally acquired data, even at the price of not attaining the fuller information given by sample examination. OCT offers such an opportunity, as a non-invasive, fast and contactless technique that provides cross-sectional images of sub-surface structures over relatively large areas. OCT has been used for the examination of artworks since 2004, but recent progress in imaging techniques has made it more applicable to resolving practical issues raised by art conservators and curators. While most applications are connected with the examination of transparent and semi-transparent layers on easel paintings, other objects, such as wall paintings, historic and archaeological glass, ceramics, semi-precious stones like jade, and even parchment, have also been successfully examined using OCT.
A major limitation of OCT for the examination of artworks is the limited transparency of their structure to the probing light utilized by the technique. OCT is an interferometric technique that uses broadband infrared radiation to determine the distance to a structure that scatters or reflects light. If the spectrum of the source is broad enough (c. 200 nm in near infrared) the precision of layer thickness measurements (the axial resolution of technique) is about 3 μm in air and 2 μm in media such as varnish. This permits detection of thin transparent layers, for example varnishes on the surface of a painting. The unique instrument used to examine the Amsterdam Sunflowers was constructed at Nicolaus Copernicus University in Toruń especially for the examination of artworks within the EU CHARISMA project. It utilizes a superluminescent light source with a spectral range of 770–970 nm. The total power measured at the object is less than 0.8 mW and the beam is never focused at the same spot for longer than 50 μs. The narrow beam of infrared light penetrates the object as far as is possible for a given absorbance of the structures at this spot – usually a fraction of a millimetre – and is collected by the instrument's optics.
Poland Supporting Elderly Persons in Polish Family and Succession Law
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- By Małgorzata Balwicka-Szczyrba, Professor of Law, Faculty of Law and Administration, Department of Civil Law, University of Gdańsk, Poland, Anna Sylwestrzak, Professor of Law, Faculty of Law and Administration, Department of Civil Law, University of Gdańsk, Poland, Marcin Glicz, Assistant Professor, Faculty of Law and Administration, Department of Civil Law, University of Warmia and Mazury in Olsztyn, Poland
- Edited by Margaret Brinig
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- Book:
- International Survey of Family Law 2018
- Published by:
- Intersentia
- Published online:
- 31 January 2019
- Print publication:
- 28 September 2018, pp 425-440
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Summary
INTRODUCTION
The legal rights of elderly persons as embedded within human rights arise from international conventions. Clear trends can be identified in Europe towards a further strengthening of the legal situation of this social group. Research on the laws regarding maintenance of elderly persons who cannot support themselves is consistent with that trend.
In the context of Polish civil law, the need for providing elderly persons with tangible support, on the grounds that their ability to earn a livelihood declines and their health condition deteriorates in the course of time, is justifiable by strong ethical considerations. The fact that seniors in Poland are entitled to file claims for maintenance under the provisions of the Polish Civil Code and the Polish Family and Guardianship Code demonstrates a cross-generational solidarity grounded in a fundamental principle whereby the working-age population lends the elderly a helping hand in exchange for their experience and assistance. Family bonds play a crucial role in that context because they give rise to the maintenance obligation as well as provide grounds for quasimaintenance claims to which the decedent's grandparents are entitled.
The object of this chapter is to discuss the question of maintenance for elderly persons in Polish family and succession law and determine whether the adopted solutions provide adequate protection to the legal interests of this growing social group. Owing to increased cross-border migration, the chapter also raises issues of conflict of laws to the extent that they relate to maintenance.
THE RELEVANCE OF RESEARCH ON THE PROBLEM OF OLD-AGE MAINTENANCE
Taking into consideration the current demographic situation, there are a number of phenomena related to maintenance in its wide sense, which used to be quite negligible in the past, but which are now emerging with growing frequency. Owing to a lengthening of the average human lifespan, old age is now becoming an increasingly longer stage in life, thereby giving rise to maintenance obligations enforceable not only against adult children, but also grandchildren or even great-grandchildren.