24 April 2010

Proceedings: Metals Conservation (2004)

Title: Metal 04: Proceedings of the International Conference on Metals Conservation
Reference: Proceedings of Metal 2004 National Museum of Australia Canberra ACT, 4–8 October 2004
ISBN: 1876944331
Link: http://www.nma.gov.au/... (pdf)

Note: Resource kindly indicated by Goran Budija.


This publication presents papers given at the International Conference on Conservation of Metals, Metal 04, held in Canberra, Australia at the National Museum of Australia, 4–8 October 2004. Organised by the National Museum of Australia, the conference brought together metals conservators from over 20 countries. The 40 papers presented in these preprints illustrate the development of the conservation and restoration of metals from a variety of perspectives and regions and of 92 authors.

Table of Contents:

Section 1: Preventive Conservation

Some recent trends in corrosion science
, T. Cole, T. Muster, D. Lau, W. Ganther (pdf, 606 Kb)

Monitoring of archaeological and experimental iron at Fiskerton, England, V. Fell, J. Williams (pdf, 1072 Kb)

Saving archaeological iron using the Revolutionary Preservation System, C. Mathias, K. Ramsdale, D. Nixon (pdf, 810 Kb)

Innovative conservation approaches for monitoring and protecting ancient and historic metals collections from the Mediterranean basin, V. Argyropoulos, E. Angelini, C. Degrigny (pdf, 153 Kb)

Corrosion monitoring and the environmental impact of decommissioned naval vessels as artificial reefs, I. MacLeod, P. Morrison, V. Richards, N. West (pdf, 741 Kb)

Corrosion and cathodic protection of iron in seawater: a case study of the James Matthews (1841), M. Heldtberg, I. MacLeod, V. Richards (pdf, 313 Kb)

SS Great Britain iron hull: modelling corrosion to define storage relative humidity, D. Watkinson, M. Lewis (pdf, 595Kb)

Section 2: Better Knowledge of Objects (pdf, 10.6 Mb)

Solder on silver: historical usage and the problem of fretting, M. van Bellegem, H. Ankersmit, R. van Langh, W Wei (pdf, 932 Kb)

Surface analysis of corroded silver coins from the wreck of the San Pedro De Alcantara (1786), I. MacLeod, E Schindelholz (pdf, 1.3 Mb)

A local microscopic model for the formation of silver mirroring on black and white photographs, G. Di Pietro (pdf, 318 Kb)

The delamination of silver sulphide layers, R van Langh, H Ankersmit, I. Joosten (pdf, 660 Kb)

Some news about 'Black Spots', G Eggert, M Weichert, H. Euler, B. Barbier (pdf, 1.1 Mb)

Trees, bunches, cauliflowers - a closer look at sulphurous corrosion on copper alloys and minerals, ('Black Spots'), M. Weichert, G. Eggert, A. Mark Jones, H. Ankersmit (pdf, 902 Kb)

Analysis of some copper-alloy items from HMAV Bounty wrecked at Pitcairn Island in 1790, A. Viduka, S. Ness (pdf, 958 Kb)

Objects from the ancient site of Qalat Rabah (Calatrava la Vieja): a case study on the characterization of Islamic gilded bronzes from Spain, J. Barrio, L. Campanella, M. Ferretti, A. Pardo, M. Retuerce (pdf, 1.8 Mb)

Electrochemical characterisation of patina protectiveness evolution on outdoor bronze sculptures, M Crespo, G Cicileo, B Rosales (pdf, 317 Kb)

Corrosion rate study of cannon at the Prince of Wales' fort, H. Croome (pdf, 260 Kb)

Analyses of Joe Byrne's armour, D. Creagh, G. Thorowgood, M James, D. Hallam (pdf, 450 Kb)

Metallurgy of armour exhibited at the Palace Armoury Valletta, Malta, D. Vella, C. Degrigny, M. Grech, A. Williams (pdf, 3 Mb)

Section 3: Better Understanding of Treatments

Plasma-reduction: Its potential for use in the conservation of metals, K. Schmidt-Ott (pdf, 6.9 Mb)

An approach to the conservation of deeply corroded archaeological silver: the polos from Crucinia, A. Olsoufieff, O. Colacicchi Alessandri, M. Ferretti (pdf, 2.8 Mb)

Atmospheric corrosion of historical organ pipes: influence of acetic and formic acid vapour and water leaching on lead, A. Niklasson, L.-G. Johansson, J.-E. Svensson (pdf, 224 Kb)

Conservation of organ pipes: protective treatments of lead exposed to acetic acid vapours, C. Chiavari, C. Martini, G. Poli, D Prandstaller (pdf, 1.2 Mb)

Overview of archaeological iron: the corrosion problem, key factors affecting treatment, and gaps in current knowledge, L. Selwyn (pdf, 231 Kb)

Corrosion layers on historic iron artefacts: Cathodic protection of iron artefacts during cleaning in acid solutions, I. de Groot, H. Ankersmit, R. van Langh, W. Wei (pdf, 257 Kb)

Electrochemical monitoring of marine iron artefacts during their storage / stabilisation in alkaline solutions, C. Degrigny, L. Spiteri (pdf, 708 Kb)

Study of corrosion potential measurements as a means to monitor the storage and stabilisation processes of archaeological copper artifacts, K. Leyssens, A. Adriaens, E. Pantos, C. Degrigny (pdf, 522 Kb)

Synergistic effects of corrosion inhibitors for copper and copper alloy archaeological artifacts, S. Golfomitsou, F. Merkel (pdf, 2.4 Mb)

Performance of copper corrosion inhibitors in a museum environment - a comparative study using FTIR spectroscopy, W. Mohamed, N Rateb, A. Shakour (pdf, 308 Kb)

Laboratory and field tests on patinas and protective coating systems for outdoor bronze monuments, P. Letardi (pdf, 287 Kb)

An EIS method for assessing thin oil films used in museums, D. Hallam, D. Thurrowgood, V. Otieno-Alego, D. Creagh (pdf, 470 Kb)

Development and evaluation of removable protective coatings on bronze, T. Shedlosky, A. Huovinen, D. Webster, G. Bierwagen (pdf, 215 Kb)

Section 4: Composite Artefacts

Characterisation of metal threads in Renaissance tapestries, A.-M. Hacke, C. Carr, A. Brown, (pdf, 1291 Kb)

Electrolytic stabilisation of a marine composite porthole and its framework, I. de Groot, C. Degrigny (pdf, 941 Kb)

Theophilus and the shrine of Vitus - a goldsmith's technique in the mirror of ancient references, H. Grieb (pdf, 584 Kb)

Stabilization of a wrecked and corroded aluminium aircraft, G. Bailey (pdf, 9072 Kb)

On again, off again - cathodic protection of a lead and ceramic water closet during desalination, J. Dickens, N. Smith, W. Gerritsen (pdf, 1326 Kb)

Antarctic observations: on metal Corrosion at three historic huts on Ross Island, P. Maxwell, A. Viduka (pdf, 1231 Kb)

Analysis, conservation and restoration of the metal threads used in Latin American colonial saints' robes, J. Thiele, SOS G. Guarda, E. Croquevielle (pdf, 932 Kb)

Article: multimedia approach to cultural heritage e-documents (2002)

Title: An integrated multimedia approach to cultural heritage e-documents
: A.W.M. Smeulders, L. Hardman, G. Schreiber, J.M. Geusebroek

Reference: ACM Workshop on Multimedia Information Retrieval, New York, 2002
: http://dare.uva.nl/... (pdf)

We discuss access to e-documents from three different perspectives beyond the plain keyword web-search of the entire document. The first one is the situation-depending delivery of multimedia documents adapting the preferred form (picture, text, speech) to the available information capacity or need exemplified by documents from the annotated media database of the Rijksmuseum. It goes beyond Quality of Service methods which insist on delivering information in the same form even if that is no longer effective. Secondly, we discuss the use of ontologies to provide access across diverse library categorizations as part of the W3C semantic web. The system translates codes in the one catalogue system into a set of codes in another expanding the potential access to digital heritage knowledge across all library systems in the ontology, such as AAT, Worldnet and IconClass. Thirdly, we discuss access to the pictorial contents of paintings by computer vision techniques, here showing in examples of Pieter de Hoogh and Johannes Vermeer which one of the two consistently painting photometric realistic in addition to adhering to the geometric realism as they both did. It is concluded access is the key issue in digital cultural heritage - be it access by situational delivery of e-document of cultural heritage, be it access to diverse knowledge systems, or be it access to the pictorial content of the picture.

Thesis: Discoloration in Renaissance and Baroque Oil Paintings (2002)

: Discoloration in Renaissance and Baroque Oil Paintings. Instructions for Painters, Theoretical Concepts, and Scientific Data

: M. H. van Eikema Hommes

: University of Amsterdam

: 2002

: 223

Type of document
: Thesis

: http://dare.uva.nl/... (pdf)

From the Introduction:
Presently, the problem of the degradation of old oil paints is the research domain of conservation science, namely the science investigating the cause of ageing processes in works of art and developing methods of retarding or countering them. Researchers focus on uncovering the chemical and physical characteristics of oil binding media and pigments. The composition of paints in old paintings is painstakingly analysed to this effect. On the basis of the results, paint systems are made that approximate as closely as possible the original composition of the old paints in the aspects deemed relevant by the researchers. By exposing these reconstructions to artificial ageing, an attempt is made to accelerate the natural ageing processes. When chemical and optical changes are charted, useful information can be acquired about the degradation processes that have occurred in the old paints. [...]

Table of contents (short version):

I. A Proposal for the Classification of Painting Methods and Recipes

II. Painters' Methods to Prevent Colour Changes Described in Sixteenth to Early Eighteenth Century Sources on Oil Painting Technique

III. Discoloration or Chiarsoscuro? An Interpretation of the Dark Areas inn Raphael's Transfiguration of Christ.
IV. Verdigris Glazes in Historical Oil Paintings: Recipes and Techniques
V. Indigo as a Pigment in Oil Painting and the Problem of its Fading

23 April 2010

Thesis: The Theseus painter (2003)

Title: The Theseus painter. Style, shapes and Iconography
: O. E. Borgers

University: University of Amsterdam
: 2003

: 330

Type of document
: Thesis

: http://dare.uva.nl/... (pdf)

From the Introduction
Thee subject of this monograph is the Attic black-figure vase painter known today as the Theseus Painter who, as we shall see, worked from about 515/510 to 480/475 B.C. First of all, the study aims at giving, as completely as possible, a full description of all the features comprising the painter's stylistic nature: painting, drawing, composition, use of added colour. These categories are, in turn, considered in relation too the potterwork, namely the types of vases the Theseus Painter decorated, the workshops with which they can be associated, and whether he might also have been involved in shaping some or all of them. [...]

Table of Contents (short version):

A. Shapes and Style
I. Vase Shapes and Style of Painting and Drawing

II. Skyphoi

III. Lekythoi

IV. Other Shapes

V. Workshop Connecting

VI. Development and Chronology

VII. Provenances

B. Iconography

VIII. Introduction

IX. Deities

X. Other Mythological Figures and Scenes as well as related Representations

XI. Herakles and Theseus

XII. Ritual, Theater and Everyday Life

XIII. A Closer Look at the Theseus Painter's Iconography

Article: the effects of white pigments and extenders (1990)

Title: Studies on the photochemical stability of synthetic resin-based retouching paints: the effects of white pigments and extenders
Authors: Paul M. Whitmore and Catherine Bailie
Reference: Cleaning, retouching and coatings: Contributions to the 1990 IIC Congress, Brussels, 1990, pp. 144-149
Links: http://www.cmu.edu/... (pdf, 568 Kb)

The durability of a paint vehicle can be strongly influenced by the pigments which it contains. This report describes an initial investigation of the photochemical degradation of paints formulated with a commercial poly(n-butyl methacrylate) and a variety of white pigments and extenders. Upon exposure to near-ultraviolet (UV) light, this resin predominantly cross-links, eventually becoming almost completely insoluble. White pigments such as rutile TiO2 and Green Seal zinc oxide do not alter this tendency but they do slow the cross-linking rate, probably by their ability to absorb UV light. By contrast, a nonabsorbing light scatterer like barium sulfate increases the rate of cross-linking, perhaps by increasing the path length of light as it becomes diffused within the paint film. Finally, pigments such as anatase TiO2 and Kadox 515 zinc oxide not only decrease the overall degradation by screening UV light, but also increase the relative importance of chain-breaking chemistries through their photocatalytic properties. Even so, loss of volatile degradation products renders these films as insoluble as the purely cross-linked systems.

Thesis: Case studies of Naples Yellow and discoloured Smalt (2003)

Title: Scientific analysis of historical paint and the implications for art history and art conservation. The case studies of Naples Yellow and discoloured Smalt.
Author: Joris Dik
University: University of Amsterdam
Year: 2003
Pages: 159
ISBN: 9090164790
Type of document: Thesis
Link: http://dare.uva.nl/... (pdf)

This thesis describes a research project in the field of technical art history. Subjects of this study are the production history of Naples Yellow and the discolouration of smalt. Naples Yellow, or lead antimonate yellow, is the most important synthetic yellow pigment in the history of the visual arts. The usage of lead antimonate covers a period of more than 3500 years, the first application of the pigment dating back to the 18th Egyptian dynasty (ca. 1500 BC). The production history of the pigment, notably over the past few centuries, is rather diverse and not well understood. This research project focussed on the European history of the pigment from the 16th to 19th century. The aim of this study was to describe different manufacturing methods and, subsequently, different forms of lead antimonate used at different periods over time. Secondly, the discolouration phenomenon of the blue painting pigment smalt was studied. Based on a number of analytical techniques a digital reconstruction showing the approximate original appearance of a smalt-discoloured painting.

Table of contents (short version):
Chapter I. Principles, Methods and Pitfalls
Chapter II. Early Production Recipes of Lead Antimonate Yellow in Italian Art
Chapter III. Northern European 18th century Lead Antimonate Yellow
Chapter IV. 19th century Naples Yellow Re-examined
Chapter V. Lead Isotope Analysis of Lead Antimonate Yellows
Chapter VI. The Digital Reconstruction of a Smalt Discoloured Painting by Hendrik Ter Brugghen

Note: Unfortunately the thesis digitisation is poor and the text is only partially readable.

Thesis: pottery in the Greek world (2002)

Title: Pottery to the people. The production, distribution and consumption of decorated pottery in the Greek world in the Archaic period (650-480 BC)
: Vincenzo Vladimir Stissi
University: University of Amsterdam
: 2002 Pages: 700
Type of document
: Thesis
: http://dare.uva.nl/... (pdf)

Table of contents (short version):

I. Introduction

Part I. Production
II. Production studies from the past to the future
III. Quantities of preserved pottery and the scale of production
IV. Archaeological remains of Greek pottery production: excavated workshops and kiln
V. Depictions of Greek potters and painters at work
VI. The voice of the workshop: signatures as a source of information on potters, painters and the ways they worked together
VII. Signatures, attribution and the size and organisation of workshops
VIII. The magic mirror of the workshop: painted and written references of potters and painters to themselves and their colleagues
IX. To the gods and the world: potters' votives as indications of wealth and status
X. Secondary evidence for the status of potters and the scale and organisation of pottery production
XI. Conclusions: pottery production as a large-scale phenomenon, hard-working potters and painters

Part II. Pottery in its Economic and Social Context: Prices, Status and Use
XII. Introduction
XIII. Prices of pottery
XIV. Domestic use of pottery and metal vessels: prices, wages, wealth and consumption patterns
XV. Pottery and metal vessels in the household: the excavated evidence
XVI. Pottery and other vessels in sanctuaries
XVII. Pottery from graves
XVIII. Conclusions: pottery as a semi-luxury

Part III. Distribution
XIX. Introduction: from pottery distribution patterns to the organisation of transport and exchange
XX. Pottery in transit: direct evidence of transport and exchange
XXI. Pottery and sea trade: the ancient written sources
XXII. Distribution patterns and distribution systems of Attic figured pottery
XXIII. Patters of production and consumption as evidence for distribution
XXIV. Conclusions: a general view and detailed insights combined
XXV. General Conclusions

22 April 2010

Article: Kubelka-Munk Theory for Color Image Invariant Properties (2002)

Title: The Kubelka-Munk Theory for Color Image Invariant Properties
Author: Jan-Mark Geusebroek, Theo Gevers, Arnold W.M. Smeulders
Reference: First European Conference on Colour in Graphics, Imaging, and Vision, Springfield, USA, 2002, pp. 463-467
Link: http://dare.uva.nl/... (pdf, 112 Kb)

A fundamental problem in color image processing is the integration of the physical laws of light reflection into image processing results, the problem known as photometric invariance. The derivation of object properties from color images yields the extraction of geometric and photometric invariants from color images. Photometric invariance is to be derived from the physics of reflection. In this paper, we rehearse the results from radiative transfer theory to model the reflection and transmission of light in colored layers. We concentrate on the Kubelka-Munk theory of colored layers, which is posed as a general model for color image formation. The model is used for decades in the painting and printing industries, and is proven to be valid for a wide range of materials. We relate the Kubelka-Munk is proven valid may be inherited to algorithms based on newer models. Furthermore, photometric invariant properties proven for one model are, by using Kubelka-Munk, easily extended to related models.

Report: Investments in Painting (2001)

Title: Investments in Painting: The interaction of monetary return and psychic income

Author: M.M.G. Fase
Year: 2001
Pages: 76
Type of document: report
ISBN: 3-902109-05-X
Link: http://dare.uva.nl/... (pdf, 495 Kb)

The financial press gives very regular attention to art and culture in their many forms. Business newspapers such as the Financial Times, the Wall Street Journal, Het Financieele Dagblad and De Financieel Economische Tijd give over plenty of space in their weekend editions to news of art auction prices and exhibitions of major or less well-known works. As well as this practical outlook, more theoretical economists have given increasing attention to the economics of art since the 1970s. There has been a remarkably large amount of research into the pricing of art and the closely associated subject of the return on purchases of art. This centres on painting in general and on individual painters. The attention to painting in the business press is without doubt prompted by the need for journalistic variety, plus the wish to impart a cultural element to the reporting. The provision of market information to readers is, of course, another significant motive. It is less simple to explain the academic interest of economists. At first sight, it seems exotic. But that is a hasty conclusion. Along with intellectual curiosity, there is probably a role for the need to apply trusted analytical methods to new areas of research. Whatever the reason, there is a place for the systematic study of the literature on the sense and nonsense of investing in painting and this is the objective of this paper. It is, however, also a report of explorations in a field that has fascinated me personally as an economist for many years.

Table of contents:

1. Introduction
1.1. A historical illustration from the art world
1.2. Practice in the international art trade

2. Investment Theory in Brief
2.1. Some basic principles of portfolio theory
2.2. Behavioural finance as an alternative approach
2.3. Art as an element of an investment portfolio

3. The Market for Paintings
3.1. The nature of the art market
3.2. Size of the art trade

4. The Price of Paintings
4.1. Auction prices
4.2. A price index for art
4.3. Example of a price index for nineteenth-century paintings

5. Art as Investment
5.1. Actual return on painting in general
5.2. The return on specific movements or painters
5.3. Return on investments in antiques and other collectibles
5.4. Once again, the return on specific painters

6. Rates of return considered closely
6.1. The monetary yield on art and the market rate of interest
6.2. The market for paintings as a segment of the international capital market

7. In Conclusion some Policy Implications

New links

I have updated some of the links of the following PhD thesis:

Microspectroscopic analysis of traditional oil paint

Laser desorption mass spectrometric studies of artists' organic pigments

Molecular studies of asphalt, mummy and Kassel earth pigments : their characterisation, identification and effect on the drying of traditional oil paint

Binding medium, pigments and metal soaps characterised and localised in paint cross-sections

Color changes and chemical reactivity in seventeenth-century oil paintings

Article: Measurement of Light Sensitivity with Micro-fading Tests (2002)

Title: Pursuing the Fugitive: Direct Measurement of Light Sensitivity with Micro-fading Tests
: Paul M. Whitmore

: in The Broad Spectrum: The Art and Science of Conserving Colored Media on Paper, H. K. Stratis and B. Salvesen (ed.), Archetype Publications, London, 2002, 241-243

: 1873132573

Link: http://www.cmu.edu/... (pdf, 245 Kb)

Article: humidity fluctuations in the deterioration of paper (2002)

Title: Explorations of the role of humidity fluctuations in the deterioration of paper
: John Bogaard, and Paul M. Whitmore

: in Works of Art on Paper Books, Documents and Photographs, V. Daniels, A. Donnithorne, and P. Smith (
ed.), International Institute for Conservation, Baltimore, 2002, 11-15
: http://www.cmu.edu/... (pdf, 511 Kb)

The control of relative humidity is generally recognized as an important consideration in the proper storage and display of paper materials. However, the amount that the humidity can fluctuate and the rate at which it can change without causing damage are still unknown. In this study, samples of cotton filter paper (Whatman No. 42) were held at room temperature in a chamber having a relative humidity that alternated between 25 and 75% every two hours. Papers were removed from this chamber at intervals and analyzed for chemical deterioration, discoloration and strength loss. After roughly 2200 humidity cycles, the paper had suffered a reduction in cellulose degree of polymerization to one-half its initial value, nearly its leveling-off DP, and its zero-span tensile strength had fallen to one-third the initial fibrer strength. Chemical products were found to be consistent with a predominantly hydrolytic degradation. These results, and the course of the strength loss during degradation, suggest that the cycling humidity causes rapid stress-induced hydrolysis in this filter paper.

SAGE temporary free access

SAGE Reference Online is allowing a free trial access to their website until May 15, 2010.

1. Log onto www.sagereferenceonline.com
2. Select "Enter SAGE Reference Online"
3. Enter the user name (maytrial) and password (freeaccess)
4. Click "Go"

Once there you can search for keywords such as 'conservation' or 'heritage'. Most likely you will receive free access to selected chapters in html format of books they have published. Nonetheless it is a valuable (temporary) resource.

Here some examples of chapters you can find:

Eastop, Dinah. "Conservation as Material Culture." Handbook of Material Culture. 2006. SAGE Publications. 21 Apr. 2010. . Chapter DOI: 10.4135/978-1-84860-797-2.n32

Alder, Christine, and Kenneth Polk. "The Illicit Traffic in Plundered Antiquities." Handbook of Transnational Crime & Justice. 2005. SAGE Publications. 21 Apr. 2010. . Chapter DOI: 10.4135/978-1-41297-618-3.n6

Orbaşlı, Aylin, and Simon Woodward. "Tourism and Heritage Conservation." The SAGE Handbook of Tourism Studies. 2009. SAGE Publications. 21 Apr. 2010. . Chapter DOI: 10.4135/978-1-8570-2107-3.n18


20 April 2010

Report: Conservation Science Research (2005)

Title: Conservation Science Research: Activities, Needs, and Funding Opportunities
: Paul M. Whitmore

: report to the National Science Foundation, 2005

Pages: 41
: http://www.cmu.edu/... (pdf, 266 Kb)

From the summary
This report describes the nature of conservation science and its support role for conservation practice. The analytical examination and study of artifact materials and construction is a central activity. These technical studies form the basis for object care and repair. When satisfactory solutions to deterioration problems are not available, focused laboratory research is done to discover the underlying processes, risk factors, and environmental conditions that put objects at risk of damage. These research studies lead to diagnostic tools and repair strategies that are then tested for efficacy and safety, and finally adapted and applied to cultural artifacts. This interchange between artifact analysis, laboratory study and development, and field applications, comprises conservation science.

Table of Contents:


The Nature of Conservation Science

Conservation Science Research Overview

- Materials identification, fabrication, and performance
- Material aging and degradation
- Restoration treatment development and testing

- Analytical and sensor technologies

Opportunities for National Science Foundation Support

- Artifact study

- Contacts between conservation scientists and specialists outside the field

- Research studies and field trials

- Educational opportunities
Lessons from the European Experience


Article: Hydrolysis of cellulose in cotton-based paper (2008)

Title: Hydrolysis of the amorphous cellulose in cotton-based paper

: Catherine H. Stephens, Paul M. Whitmore, Hannah R. Morris, and Mark E. Bier

: Biomacromolecules 9 (4), 2008, 1093-1099

: http://www.cmu.edu/... (pdf, 266 Kb)

Hydrolysis of cellulose in Whatman no. 42 cotton-based paper was studied using gel permeation chromatography (GPC), electrospray ionization-mass spectrometry (ESI-MS), and uniaxial tensile testing to understand the course and kinetics of the reaction. GPC results suggested that scission reactions passed through three stages. Additionally, the evolution of soluble oligomers in the ESI-MS data and the steady course of strength loss showed that the hydrolysis reaction occurred at a constant rate. These findings are explained with a more detailed description of the cellulose hydrolysis, which includes multiple chain scissions on amorphous segments. The breaks occur with increasing frequency near the ends of amorphous segments, where chains protrude from crystalline domains. Oligomers unattached to crystalline domains are eventually created. Late-stage reactions near the ends of amorphous segments produce a kinetic behavior that falsely suggests that hydrolysis had ceased. Monte Carlo simulations of cellulose degradation corroborated the experimental findings.

Article: calcium washing treatments on paper (2001)

Title: Effects of dilute calcium washing treatments on paper
Author: John Bogaard, and Paul M. Whitmore
Reference: Journal of the American Institute for Conservation 40, 2001, 105-123
Link: http://www.cmu.edu/... (pdf, 1.03 Mb)

Dilute aqueous solutions of three different calcium salts have been compared for their effectiveness as wash treatments for stabilizing the cellulose of paper objects. Treated paper samples were evaluated for chemical changes resulting from the treatment and from subsequent accelerated thermal aging. The extent of alkaline damage of the treated sheets was found to be insignificant even for photo-oxidized papers. The treatments slowed the deterioration of the paper during thermal aging, but eventually the protective benefit weakened. Neutralization of acid in the sheets had a greater stabilizing effect on the paper than did the presence of calcium. Dilute alkaline calcium washes were less effective in retarding degradation of photo-oxidized papers than the same washes of unoxidized sheets. Chemical reduction of the photo-oxidized paper followed by washing with the dilute alkaline calcium solution was very effective at slowing its deterioration during thermal aging. Treatment with the dilute alkaline calcium solution also slowed photo-oxidation of paper during exposure to near-ultraviolet radiation.

Article: identifying red lakes (2009)

Title: An improved method for identifying red lakes on art and historical artifacts
Author: Barbara H. Berrie
Reference: PNAS September 8, 2009, vol. 106, no. 36, 15095-15096
Year: 2009
DOI: 10.1073/pnas.0907727106
Link: html, pdf (545 Kb)

From the article:
As Leona notes in a recent issue of PNAS, art and objects of cultural heritage hold information about the technology, trade, and aesthetics of a people. This knowledge can be accessed through chemical and material analysis combined with an understanding of the history of technology, science, and art. The information learned is of great value, especially for ancient objects that are so old we have no chance of finding written documentation such as bills of lading, inventories, or manuals and treatises that we may consult for descriptions of the materials used in their creation.

19 April 2010

Article: differentiation of layers by optical microscopy (2008)

Title: The visible image is not always correct: the differentiation of layers by optical microscopy in samples’ cross sections
Author: Carolina Barata, António João Cruz, Marta Ferro
Reference: e-conservation, 7, 2008, pp. 21-25
Link: html 1, html 2, pdf 1, pdf 2

The stratigraphic characterization of polychrome surfaces in works of art is frequently done through the observation of cross-section samples by optical microscopy (OM). Three examples that show some limits to this method are presented here. In samples where at first only one layer was visible, several strata were detected through electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). These and other examples ought to be taken into consideration by conservators, who should be aware of similar possibilities in other cases.

Article: light bleaching of acrylic artists' medium (2002)

Title: The light bleaching of discolored films of an acrylic artists' medium
Author: Paul M. Whitmore, Val G. Colaluca and Hannah R. Morris
Reference: Studies in Conservation, Vol. 47, No. 4, 2002, pp. 228-236
Link: http://www.cmu.edu/... (pdf, 7.29 Mb)

Films of Liquitex gloss medium on gesso that had been discolored either by dark storage of the original product or from addition of colored matter extracted from linen canvas were bleached by brief exposure to high-intensity visible light. After 20 hours of exposure to a UV-filtered xenon lamp, an exposure dose equivalent to four days under UV-filtered daylight fluorescent lights, the intrinsic yellow color of the naturally aged films (initial Yellow Index of 23) was found to bleach significantly (about 40% of the original color remained after bleaching). For films that were discolored from material extracted from linen canvas (initial Yellow Index of 37), only a small fraction of the yellow discoloration was bleached in the exposure (about 70% of the original color remained after bleaching). Greater degrees of bleaching would have required much longer light exposures, for the bleaching rate decreased progressively during the exposure. In subsequent dark storage of the bleached films, the original levels of discoloration returned. However, when bleached films were subsequently exposed to periodic, moderate light levels simulating gallery conditions, the films retained much of the appearance benefits that had been gained from the bleach treatment.

18 April 2010

Article: 'Virtual Fading' of art objects (2007)

Title: 'Virtual Fading' of art objects: simulating the future fading of artifacts by visualizing micro-fading test results
Author: Hannah. R. Morris and P. M. Whitmore
Reference: Journal of the American Institute for Conservation 46, 2007, 215-228
Link: http://www.cmu.edu/... (pdf, 590 Kb)

The authors examine the importance of visualizing the color changes of colorants exposed to visible light, and use this information to create a “virtually faded” art object. The color information collected during lightfastness measurement (as CIE L*a*b* values) with a micro-fading tester can be transformed to RGB values, and color swatches representing the original and faded colors displayed on a computer monitor. Such demonstration of the appearance changes can help to visualize the degree of color change and the precise nature of that change, which may not be simple lightening of the color but could also include hue or chroma changes. Judging the visual impact of a light-induced color change requires viewing the altered color in its context within a particular image. Digital renderings of paintings were created with Adobe Photoshop and Matlab, using a number of fugitive colors, the fading characteristics of which had been recorded with prolonged micro-fading tests of 100–1920 minutes in duration depending on the light dosage required for the color to no longer be hanging. Based on this information describing the appearance of each of the colors as it changes with light exposure, simulations of the “virtually faded” painting were generated, representing the image appearance with incremental light exposure. Such virtually faded simulations can offer insight into the severity of particular light-induced color changes, allow targeting of crucial color areas that might warrant tracking in a color monitoring program,and inform discussions about the “end of exhibition life” of an object and appropriate exhibition rotation policies.

Article: Optical brighteners in black-and-white photographic paper (2007)

Title: Optical brighteners in black-and-white photographic paper: appearance and degradation

Author: Sandra A. Connors-Rowe, Paul M. Whitmore, and Hannah R. Morris
Reference: Journal of the American Institute for Conservation 46, 2007, 199-213
Link: http://www.cmu.edu/... (pdf, 444 Kb)

Forty-five optically brightened black-and-white photographic papers from 12 manufacturers spanning 1956–2006 were studied to evaluate the brightener’s impact on appearance and its light sensitivity under simulated daylight conditions. The appearance tests showed both small and large changes in appearance when the optical brightener was activated by inclusion of UV in the illuminating light source. All papers showed a decrease in the Yellowness Index value upon brightener activation, indicating a change in appearance to a color that is whiter than its unbrightened version. Three papers that were originally warm white in appearance, however, remained somewhat yellow in color even with activation of their optical brighteners. All of the 45 papers experienced some optical brightener loss as a result of prolonged exposure to simulated daylight with UV wavelengths included; many also experienced other color changes such as bleaching or yellowing of the paper substrate and loss of a chromophore at 570 nm. All papers experienced color change rates similar to that of Blue Wool Standard 3 or 4 when exposed to light containing UV and would be considered moderately sensitive to light exposure.