STRUCTURE OF A PAINTING WORK. STRATIGRAPHIC SECUENCE.

Transcription

1 THEMATIC UNIT Nº 3 STRUCTURE OF A PAINTING WORK. STRATIGRAPHIC SECUENCE BASIC DEFINITIONS STRATIGRAFIC SECUENCE OF A PAINTING WORK SUCCESSION OF LAYERS AND ITS IMPORTANCE IN THE MAKING OF A PICTORIALWORK STRATIGRAPHIC ANALYSIS IN RESTORATION BIBLIOGRAPHY AND WEB LINKS. 1

2 3.1. BASIC DEFINITIONS. A painting is not only a colored surface, is also a three-dimensional object consisting of a series of layers of different thickness and composition. Those layers are a direct translation of the successive applications and manipulations that are performed on the support suitably prepared by various materials, and forming a group will result in the finished work. So the sequence of layers for the SUPPORT first, his PRIMER, the LAYER OR PICTORIAL COATING, and finish generally in the form of VARNISH, together constitute the stratigraphic sequence STRATIGRAFIC SECUENCE OF A PAINTING WORK. Thus, the elements of a painting can be studied in a stratigraphic cut. If you do a microscopic analysis of a cross section of the strata or layers of an easel painting we see that is composed of several layers as shown in the following scheme: Varnish layer, pictorial layer, primer, support. Table or fabric supports. Since the sixteenth century became more widespread the use of fabrics as a suport for painting, especially in Europe, it is essential to always use good primers to give body and lose the roughness of the fabric. Preparation or primer base. Is the uniform layer that is applied on the canvas or panel to block the pore. Its function is to isolate the paint layer from the support so the fabric defects do not pass to the painting and remains a smooth texture. This consists of a binder and a filler. Another function of the primer is to preserve the supports of oxidation produced by the direct contact with the pictorial binders used. Thus it is known that an 2

3 insufficiently primed canvas can cause the oil ends up burning slowly, in an action similar to that occurred when abusing with lye in cloth washing. Layer of paint. Is the one besides de finishing varnish that is the more external and visible layer of the painting. It is compounded of pigments and binders, and depending on the nature of the binder, we distinguish various kinds of paints linked to the painting procedure used. For example the tempera painting technique that uses water as a vehicle to dissolve and dilute the pigment presents a pigment that previously has been bound by animal or vegetal glue, gum, casein or egg. In the case of encaustic or oil we meet with wax or fatty procedures that does not dilute in water and in which pigments are grounded and bound in wax and drying oil. Therefore the nature of the paint layer will depend on the procedure used, although it s traditional or recent. Varnish or protective coating. This is the last and outermost layer has a painting. Varnishes and binders, before the synthetic resins appeared, were made with resins such as Dammar, the mastic, copal or amber, turpentine and oils like linseed one SUCCESSION OF LAYERS AND ITS IMPORTANCE IN THE MAKING OF A PICTORIALWORK. A work of art is a stratified set, it becomes in stages. The end result is conditioned precisely by these stages. In this sense the first step comes through the preparation of supports, for it is necessary to study the raw materials used and the followed steps in its manufacturing. It is also necessary to study the pigments used, for this purpose we must take into account its denomination, cataloging, qualities and chemical composition so as observe the ways to create polychrome variations with them. The applying of color layers and the ways of doing also conditionates the different expressive aspects: layers of colors in transparency to create secondary colors, saturated and opaque layers, pasta and diverse textures layers, burnished and saturated layers. Before any work is necessary to consider that each procedure (binder + pigment) requires a kind of support and a particular type of primer, or at least compatible with the layer of coating pictorial procedure thought to work with. This means that if we work with meager binders, such as vinyl or acrylic polymers tempers, we should not start from a primer containing 3

4 oils, waxes, or components of fat-oily nature. This issue is very IMPORTAN because the stratigraphic succession of the work requires consistency and stability resulting in a compact aspect STRATIGRAPHIC ANALYSIS IN RESTORATION. The first researchers who dealt with the study of artwork noted the advantages of the analysis of the present strata and began to develop techniques for obtaining a cross section. With the stratigraphic analysis of very small pieces of representative samples of artwork, you can get a wide direct vision that facilitates the study and investigation of different strata or layers that can be found in a given material, since most of the works has a structure of overlapping layers that form it. The clearest case is that of a painting. The amount of information you can get is valuable, for example, sequence data layers, delivery techniques and conservation status and can compensate, in part, the potential harm is done by obtaining the sample directly from the work. The outermost stratus are visible, but can be as important or more the subordinate strata that serve as a support and base: stratigraphic analysis is able to spell them out. In general, we prefer a small sample, but complete, that a larger or partial or that manifest tendency to fragment in parallel to the layers. Although it has been the most common method of examination, because of its invasiveness, however, sampling is less than ideally compatible with conservation ethics; it is severely restricted with respect to the amount of material extirpated from the artwork. Sampling is also rather limited in that it provides only very local information. There is, therefore, a great need for a noninvasive method with sufficient in-depth resolution for resolving the stratigraphy of works of art. Optical Coherence Tomography (OCT) is a noninvasive, noncontact method of optical sectioning of partially transparent objects, with micrometer-level axial resolution. The method utilizes near-infrared light of low intensity (a few milliwatts) to obtain cross-sectional images of various objects; it has been mostly used in medical diagnostics. Through the serial collection of many such images, volume information may be extracted. The application of OCT to the examination of art objects has been in development since There also have been done investigations to demonstrate the potential of single-sided nuclear magnetic resonance (NMR) sensors to access deeper layers of paintings noninvasively by means of high-resolution depth profiles spanning several millimeters. The performance of the sensor in resolving painting structures was tested on models for which excellent agreement with microscopy techniques was obtained. The 4

5 depth profiling NMR technique was used in situ to investigate old master paintings. The observation of differences in NMR relaxation times of tempera binders from these paintings and from artificially aged panels raises the possibility to differentiate between original and recently restored areas BIBLIOGRAPHY AND WEB LINKS. WEB LINKS: Appl. Phys. Lett. 93, (2008); doi: / (3 pages) Noninvasive nuclear magnetic resonance profiling of painting layers PRESCCIUTI Federica 1, PERLO Juan 2, CASSANOVA Federico 2, GLÖGGLER Stefan 2, MILIANI Costanza 1,BLÜMICH Bernhard 2, Brunetto BRUNETTI Giovanni 1, and SGAMELLOTTI Antonio 1 1 Centre of Excellence SMAArt and ISTM-CNR, c/o Chemistry Department, University of Perugia, Via Elce di Sotto 8, Perugia 06123, Italy 2 Institut für Technische Chemie und Makromolekulare Chemie, Rheinisch-Westfälische Technische Hochschule, Aachen D-52056, Germany published online 22 July American Institute of Physics. [Accessed: February 7, 2012]. Available at: Structural Examination of Easel Paintings with Optical Coherence Tomography TARGOWSKI Piotr*, IWANICKA Magdalena, TYMINSKA-WIDMER Ludmiła,SYLWESTRZAK Marcin and KWIATKOWSKA Ewa A. Institute of Physics, Nicolaus Copernicus University, ul. Grudziadzka 5, Toruń, Poland Institute for the Study, Restoration and Conservation of Cultural Heritage, Nicolaus Copernicus University, ul. Gagarina 7, Toruń, Poland 5

6 Acc. Chem. Res., 2010, 43 (6), pp Publication Date (Web): December 31, 2009 DOI: /ar900195d Copyright 2009 American Chemical Society. [Accessed: February 7, 2012]. Available at: 6