Studies in Conservation

The first issue of the latest volume of IIC's Studies in
Conservation--Volume 56 number 1-- has now been published and Volume
56 number 2 is in preparation.  56-1 is now available from the IIC
office (see foot of this posting) and 56-2 will be available
shortly.

Studies in Conservation 56(1) (2011).
The contents of 56-1 are as follows:

Review Paper:

    Cennino Cennini's Il Libro dell'Arte, A Historiographical Review
        Thea Burns

        This paper presents a historiography of Cennino Cennini's Il
        Libro dell'Arte (c.1400). It highlights the peculiarities
        and purposes of several editions, translations and principal
        commentators, and examines how the Libro was used as a
        source of inspiration and technical instruction by
        nineteenth- and twentieth-century painters. It draws
        attention to many papers and books that are not well known
        in the conservation community but deserve to be. It notes
        that Cennini's text has been used as if it was the only
        written technical source for the Middle Ages and Renaissance
        and has been applied widely to the study of European
        paintings; recent scholarship has suggested that its
        contents are more restricted in time and space, and that it
        needs to be used more critically by conservators and others.

Research Papers:

    India Rubber Painting Grounds in Britain and France in the
    Nineteenth Century
        Pascal Labreuche

        The use of rubber as a component of the grounds of artists'
        canvases appeared simultaneously in Britain and France, and
        such primed canvases became commercially available from
        around 1835 to the beginning of the 1850s. India rubber (so
        called as it first came from the 'India' discovered by
        Columbus) or elastic gum was at the time a new material in
        the visual arts. More generally, this product found vogue in
        many fields of manufacturing. The addition of rubber to
        grounds applied to artists' canvas was an extension of the
        process of waterproofing utilitarian fabrics then common in
        Britain and France. Rubber-based grounds were first
        mentioned in the conservation literature in 1981 by Byrne.
        The present paper seeks to identify manufacturers and
        individuals involved in the development of rubber-based
        artists' grounds. The study is based on textual sources and
        the few material sources which remain: handwritten recipes,
        patents, press releases, catalogues, marks on fabrics, and
        rare paintings on manufactured French and English fabrics.
        The deterioration aspects of grounds containing rubber are
        illustrated.

    Determination of the Annual Light Exposure Received by
    Two-Dimensional Museum Objects Displayed on Vertical Surfaces
    using Photometric Measurements
        Julio M. del Hoyo-Melendez
        Marion F. Mecklenburg
        Maria Teresa Domenech-Carbo

        Accurate estimates of cumulative light exposure are an
        important prerequisite for the assessment and limitation of
        photochemical damage to museum objects on display. The task
        is complicated because spotlights used to highlight
        particular features illuminate objects' surfaces unevenly,
        and also because indirect light sources, for example diffuse
        sunlight within exhibition spaces, result in changing total
        illumination levels throughout the day and seasonally. This
        paper presents a methodology for determining the annual
        light exposure of 2-D objects by combining the results of
        continuous light readings adjacent to the object and one-off
        point measurements over its illuminated surface, a method
        that allows a more accurate estimate of total exposure than
        either monitoring method alone. Two pieces of information
        are required to calculate cumulative exposure: first, the
        ratio of direct to indirect lighting, which is arrived at by
        quantifying the amount of visible light falling on the
        object relative to that received by its surroundings; and,
        second, the diurnal and seasonal variation in illuminance of
        indirect light sources, particularly diffuse daylight. Two
        paintings in different galleries exposed to different ratios
        of diffuse sunlight to direct artificial light-one low and
        the other high-were used to refine and test the method.

    An Analytical Method for the Determination of the Climatic
    Distance between Different Microclimates for the Conservation of
    Wooden Cultural Heritage Objects
        Paolo Dionisi-Vici
        Matteo De Vincenzi
        Luca Uzielli

            This paper describes a statistical methodological
            approach for the comparison of different microclimates.
            This method was developed as a tool for choosing a new
            microclimate for temporary moves. At the present stage
            of development, this method is not intended to be used
            for identifying harmful conditions. The proposed method
            is based on experimental evidence indicating that the
            sensitivity of wooden objects to environmental
            fluctuations can differ from object to object, depending
            on many physical and mechanical parameters. Some objects
            could be affected by fluctuations that would not be
            significant for other objects. The parameter adopted in
            this work is equilibrium moisture content, that is the
            equilibrium value that a wooden object would tend to
            maintain under stable temperature and relative humidity
            values for a long period of time. It must be considered
            potential because in a fluctuating climate it is never
            reached. The methodology is based on two parts. The
            first describes in a mathematically simplified way how
            climate is perceived by objects with different
            sensitivities. The second analyzes the climatic distance
            between different climatic data sets using the
            mathematical technique of principal components analysis,
            according to the previously defined object's
            sensitivity. As a test of the proposed method, four
            different microclimatic cases studies are analyzed and
            the results described.

    Technical Study and Conservation Treatment of a Horse Model by
    Dr Auzoux
        Barbara Dumont
        Anne-Laurence Dupont
        Marie-Christine Papillon
        Gael-Francois Jeannel

            It also unveiled further information not reported to
            This paper reports on technical investigations and
            anatomical model of a horse created in the and stable
            climatic conditions for the storage of chosen as a
            consolidant. The method developed proved confirmed
            previous data published on Auzoux models. conservation
            work carried out on a papier mache consolidation of the
            paint layers. A gelatine with a date as this type of
            research on such a large Auzoux distortion of the
            internal metal structure, and its good adhesive power
            and a high gel strength was mid-nineteenth century by Dr
            Auzoux. The object model had never been carried out
            before. of the horse was conducted using historic
            sources as other deteriorated Auzoux models. In order to
            better painted surface exhibited severe flaking. The
            suffered from a structural unbalance due to the surfaces
            were prepared and were artificially aged techniques and
            materials involved in the fabrication the model. A
            scientific examination of the treatments mainly entailed
            surface cleaning and under cycling heat and humidity.
            This experimental understand the flaking process,
            mock-ups of painted very effective and could be applied
            in the future on well as analytical investigation. The
            findings work showed the importance of maintaining
            optimal

The contents of 56-2 will be as follows:

Review Paper:

    Conservation of Thangkas, A Review of the Literature since the
    1970s
         Sabine Cotte

            Thangkas (Tibetan painted banners) are religious objects
            still in use in their original Himalayan context; they
            are also encountered in Western collections where they
            are considered as ethnographic objects or works of art.
            Conservation of thangkas goes far beyond technical
            considerations and encompasses issues such as treatment
            of sacred objects in another culture, trans-disciplinary
            conservation and ethics in the conservation of living
            cultural heritage. This article reviews the publications
            on thangkas focused either on techniques and materials
            or on conservation treatment options. Treatment
            approaches have varied since the 1970s when thangkas
            were first mentioned in the conservation literature.
            These are discussed in the context of the conservation
            of living heritage and its role in the presentation and
            perception of diverse cultural identities.

Research Papers:

    Colour Change in Sample Reconstructions of Vincent van Gogh's
    Grounds due to Wax-Resin Lining
        Emily Nieder
        Ella Hendriks
        Aviva Burnstock

            This study examined the visual impact (colour change) of
            wax-resin lining on sample reconstructions of Vincent
            van Gogh's grounds, made as part of the Historically
            Accurate Reconstructions of Oil Painters' Materials
            (HART) Project. The lining method followed that used by
            J.C. Traas for lining paintings by Van Gogh between 1926
            and 1933. Visual changes in the ground samples after
            lining were noted and colour change was measured using a
            reflectance spectrophotometer. The binding medium of the
            ground was found to be the most significant factor, with
            the greatest darkening occurring in samples bound in
            glue, followed by emulsion and oil. The presence and the
            method of application of size used in the preparation of
            the ground samples and the inorganic composition also
            influenced darkening and colour change as a result of
            lining. Grounds on unsized canvas darkened the most,
            while a layer of gelled size reduced impregnation with
            the adhesive and concomitant darkening. Chalk-containing
            grounds darkened more than grounds containing barium
            sulphate or lead white. Comparisons between the
            reconstruction samples and wax-resin lined paintings by
            Van Gogh highlighted difficulties in attributing the
            darkening of the ground in the paintings to the lining
            or to other factors, such as staining by original oil
            binder in the paint.

    On the Utility of Spectral-Maximum-Based Automated Thread
    Counting from X-Radiographs of Paintings on Canvas
        C. Richard Johnson, Jr.
        Don H. Johnson
        Naoto Hamashima
        Heui Sung Yang
        Ella Hendriks

            This paper establishes that the two-dimensional Fourier
            transform, spectral-maximum-based extraction of thread
            density appears suited to automatic thread counting from
            scanned X-radiographs of paintings for a range of
            European painters from the seventeenth century to the
            early twentieth century. With regularly woven canvas,
            striping occurring in color-coded maps of local thread
            count can be used to identify rollmate candidates
            originally separated by as much as a few meters, maybe
            more. These results suggest that recently developed
            spectral-maximum-based thread counting algorithms are
            sufficiently sophisticated to support major efforts in
            archival thread counting as key forensic data in a
            variety of art historical investigations. Still, the
            canvas and priming used by some artists require a more
            refined approach to automated thread counting than a
            simple spectral-maximum-based scheme.

    Pigments in a Paint Box belonging to Whistler in the Library of
    Congress
        Elisabeth West FitzHugh
        Marco Leona
        Nobuko Shibayama

            A paint box and palette that belonged to the American
            painter James McNeill Whistler (1834-1903) are in the
            Library of Congress, Washington, DC. There are 37 tubes
            of paint in the box, including 6 in a separate cardboard
            box labeled Spectrum Colors. There are also painting and
            etching tools. The tubes were supplied by five British
            colormen except for the Spectrum Colors, which came from
            the American firm of Devoe and Raynolds Inc. Some of the
            tube labels are missing or illegible. The pigments were
            identified using polarized light microscopy, X-ray
            powder diffraction, high performance liquid
            chromatography, and Raman spectroscopy. Information from
            Devoe and Raynold's catalogs suggests that the Spectrum
            Colors were not available before 1909; toluidine red,
            found in one Spectrum Color, was first synthesized in
            1904. Thus, the Spectrum Colors must have been put in
            the paint box after Whistler's death. Of the other
            pigments in the box, three - graphite, emerald green and
            synthetic malachite-are not known to have been used by
            him, but it may be that they are yet to be identified.
            The paint box was given to the Library of Congress by
            Joseph and Elizabeth Pennell in 1917, 14 years after the
            artist's death, and it is not known whether the paint
            box was used during that time.

    Digital Modeling and Virtual Restoration of a Giant Iron Statue
    of a Lion in China (AD 953)
        Xiao-dong Wang
        Wei Wang

            The giant iron statue of a lion is a significant ancient
            work of art in China, built in ad 953. Natural
            conditions and a complex history over a period of about
            a thousand years have created severe damage. This study
            assembled a complete three-dimensional (3D) digital
            model of the statue for its protection and scientific
            studies carried out during the restoration process. The
            model illustrates the successful application of 3D laser
            scanning technology for precise documentation of a
            monumental iron object. In addition, virtual restoration
            and reconstruction of the statue have been realized by
            means of manipulating the 3D model, thus the educational
            and academic value of the digital model is enhanced. The
            final appearance of the virtual statue may help increase
            understanding of the culture of previous centuries in
            China.

    An Improved Oddy Test Using Metal Films
        Sheng Wang
        Lingdong Kong
        Zhisheng An
        Jianmin Chen
        Laimin Wu
        Xinguang Zhou

            The Oddy test is an 'accelerated' corrosion test
            employed by museums to evaluate the suitability of
            materials proposed for use in display and storage cases.
            The standard Oddy test requires a 28-day test period,
            and the results are assessed by visual observation. This
            paper describes an improved test method, which could
            reduce the length of the test period by half. The
            improved method uses metal films as substitutes for the
            traditional metal coupons posing as 'surrogate art
            object'. The new test results are then evaluated by
            computer with digital image processing for more
            objective selection of less corrosive materials.

    On the Early History of Museum Environment Control,
    Nationalmuseum and Gripsholm Castle in Sweden, c. 1866-1932
        Mattias Legner

            Despite the fact that there have been investigations
            into the historical development of indoor climate
            recommendations, to date very little research has been
            carried out on how climate control in museums was
            actually implemented in the past. This article examines
            the development of climate control in two Swedish museum
            buildings up until the 1930s: Nationalmuseum and
            Gripsholm Castle. Nationalmuseum was erected to make the
            state collections more accessible to the public and to
            provide monitoring and central heating. At that time
            knowledge of climatic conditions in museums was tacit
            and based on personal experience rather than on
            scientific studies. However, in the early twentieth
            century the problem of managing museum climate increased
            as curators became more aware of the dehydrating effects
            of central heating on panels and polychrome wood. The
            first successful attempts to automatically control
            indoor climate were carried out at Gripsholm in the
            1920s. The focus was then on monitoring and controlling
            temperature rather than relative humidity, but these
            early attempts also showed that extreme levels of
            humidity could be avoided in an environment that had
            never been designed for permanent heating. This article
            examines attempts at managing indoor climate between the
            1860s and the 1930s.

Graham Voce
Executive Secretary
International Institute for Conservation
6 Buckingham Street
London WC2N 6BA
UK
+44 20 7839 5975
Fax: +44 20 7976 1564


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                  Conservation DistList Instance 24:50
                    Distributed: Monday, May 2, 2011
                       Message Id: cdl-24-50-009
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