Objects Specialty Group--Abstracts

Abstracts for the Objects Specialty Group Session
AIC Annual Meeting
St. Louis MO 1999

Here are the abstracts for the Objects Specialty Group Session,
which will be held on Friday 11 June 1999 at the annual AIC meeting.
The abstracts are listed in order of presentation. The talks are
each 20 minutes long, and there will be several minutes scheduled
for questions and discussion after each presentation.

A Preliminary Investigation into Material Culture Composed of
Western Red Cedar (Thuja plicata) Bark
Ingrid Neuman, Objects Conservator
Berkshire Art Conservation, Williamstown MA

    This presentation will provide a general overview of typical
    examples of two and three-dimensional objects made from western
    red cedar found with museum collections. The basic botanical and
    chemical structure of this inner phloem material will be
    illustrated at the microscopic level with the aid of botanical
    staining methods. A discussion of manufacturing processes and
    traditional tools will follow. Deterioration mechanisms, both
    macroscopic and microscopic, will also be discussed.

    One institution's history of cedar bark conservation treatments,
    which involved the use of a wide range of adhesives, was studied
    for this project. Technical examinations of previously treated
    cedar bark mats with scanning electron microscopy and energy
    dispersive x-ray analysis were undertaken, and the tensile
    strength of both new and old samples of cedar bark were
    measured. One treatment of an individual cedar bark mat will be
    outlined here, including suggestions for exhibition mounting and
    storage, and an evaluation of a treatment after ten years will
    be presented. An updated bibliography will be included.

    Although cedar bark has historically been manipulated for a wide
    variety of functional purposes by Native groups in the Northwest
    United States, and collected by anthropological and natural
    history museums internationally, conservation and preservation
    strategies have not been widely written about. The author hopes
    that this paper will initiate more discussion of and research
    into this extremely versatile material.

Tapa: You Can't Beat It (Enough)
Natalie Firnhaber, Conservator
National Museum of Natural History, Anthropology Conservation
Laboratory, Smithsonian Institution, Washington, DC.

    Conservation of tapa, or barkcloth, is now familiar to many
    ethnographic conservators. This paper will discuss the evolution
    of techniques in our laboratory at the National Museum of
    Natural History in repair, storage, labeling, and photography.
    It will also briefly describe experimental techniques in
    washing, backing, and deacidification. Our use of volunteers in
    performing some of these procedures will also be discussed.

The Treatment of a Haida Totem Pole: All Things Considered?
Leslie Williamson, Conservator
National Museum of the American Indian, Smithsonian Institution,
Research Branch, Bronx, NY

    This totem pole was carved in about 1875 for Chief Eagle of Old
    Kasaan Village, Prince of Wales Island, Alaska. It was acquired
    by the Museum of the American Indian/Heye Foundation in the late
    1930's and erected outdoors in New York City in 1941. In 1980,
    it was placed flat on blocks on the grounds of the museum's
    collections storage facility in the Bronx, NY. More recently,
    the pole has been selected as possible for exhibit in 2003, in
    the future museum building of the National Museum of the
    American Indian/Smithsonian Institution in Washington D.C. This
    prompted the current treatment project.

    As with all oversized artifacts, the process of developing a
    treatment plan required much more time, thought, research, and
    advice than is usual for smaller scale projects. The
    conservation of this pole has been on going, involving numerous
    conservators, contractors, and interns over a span of three and
    a half years. The complex nature of the treatment necessitated
    drawing on the expertise of objects and wooden artifact
    conservators, a traditional Haida artist, curators, and
    engineers. There were multiple goals for the treatment: moving
    the pole to a new location, the request for exhibit, and the
    projected expectations a Haida viewer might have for the pole.

    The treatment is still not complete, but the process of getting
    to the current state, and the expectations and planning of what
    will follow, are of greater interest than simply listing the
    procedures and materials used. I will examine the process of
    deciding why and how to treat the object; the importance of
    working within the expectations of other departments in the
    museum; the desire to consult with Native people from the pole's
    region of origin; and the need to balance and justify these
    potentially conflicting view points into a cohesive project.

A Method for Packing and Handling Donald Judd's Brass and Copper
Sculptures Using Corrosion Intercept: A learning curve
Eleonora Nagy, Associate Conservator for Sculpture
Solomon R. Guggenheim Museum, New York, NY

    The Solomon R. Guggenheim Museum's Panza Collection contains
    five sheet-metal sculptures by Donald Judd, which are made of
    brass or copper. These significant examples of 20th century
    minimalist sculpture with their inherently delicate, polished
    surfaces place extreme demands on conservators in terms of
    treatment, maintenance and preventive conservation.

    Approximately five years ago, conservators at the Guggenheim
    Museum began to develop a treatment and maintenance program
    addressing issues of cleaning and maintenance of the Judd
    sculptures. Soon it was realized that preventive measures, such
    as exceptionally careful packing, handling, and installation,
    had to be considered as essential parts of any preservation
    program. The research for new packing materials and methods has
    continued since. This presentation will describe the latest
    results of packing and handling experiments with Judd's brass
    and copper sculptures: a new Corrosion Intercept 'Tent Packing
    and Handling System'. The system is designed to allow handling
    of the sculpture from storage to installation without touching
    the surface of the works. It avoids direct contact of any
    packing material with the surface of the sculpture and provides
    an enclosed, controlled environment for the works in storage.
    Although the presentation will focus on one sculpture,
    consisting of six large sheet brass cubes with sides made of
    orange Plexiglas, several other works will be discussed as
    examples of various stages of the design in process. The simple,
    effective, and economical Intercept 'Tent' system can be adapted
    easily to other extremely sensitive minimalist sculptures.
    Experience with the 5-year performance of Intercept as well as
    the performance of the packing system will be described.

    This work is part of a larger preservation project at the
    Solomon R. Guggenheim Museum focusing on minimalist art which
    has been funded by the Institute for Museum and Library Services
    and the Getty Grants Program.

The Effects of Commercial Photographic Dulling Sprays on Silver
Objects
David Harvey, Associate Conservator, Metals & Arms Laboratory
The Colonial Williamsburg Foundation, Williamsburg, VA

    The use of photographic dulling sprays on reflective surfaces to
    eliminate glare is widespread: one needs only to turn the pages
    of the major auction and exhibition catalogues to appreciate the
    scope of use of this material. In July of 1997, conservators at
    the Metals & Arms laboratory at Colonial Williamsburg discovered
    that the Scottish silver Newbattle Kirk Cup made by George
    Cleghorne (ca. 1644-1646) had been coated with a commercial
    photographic dulling spray by a volunteer photographer. The
    photographer had applied the spray, photographed the silver cup,
    and then wiped the surface with a cloth. The cup was further
    affected in storage by an HVAC failure during a thunderstorm in
    which the relative humidity spiked to 90% within a 24-hour
    period.

    The silver cup had many black tarnish spots that, when viewed
    under low magnification with a binocular microscope, appeared as
    etched tide rings around seams and pores in the silver. The
    micron-sized, abrasive crystals from the dulling spray were
    driven into every seam, pore, and scratch in the silver. A new
    scratch pattern appeared where the photographer had wiped the
    surface.

    Traditional silver cleaning and polishing techniques would
    exacerbate the situation; the micron sized crystals had to be
    released from the silver substrate before tarnish removal could
    be undertaken. A treatment plan was formulated using a non-ionic
    Pluronic surfactant in solvent and focused ultrasonic energy
    from a Misonix XL 2007 ultrasonic wand. After the particles were
    completely released from the surface a traditional silver
    cleaning treatment was carried out.

    Although the treatment was successful, it was extremely
    time-consuming. Any time saved in photographing the cup with the
    dulling spray was far outweighed by the labor-intensive
    treatment. Furthermore, some irreversible damage to the object
    did occur.  This is a problem that can and should be prevented,
    and it is hoped that dissemination of this paper will help raise
    the awareness of our colleagues in museums and auction houses
    who photograph historic and artistic metal objects.

Evaluation of Three Protective Coatings for Indoor Silver Artifacts
Chandra L. Reedy, Associate Professor
University of Delaware, Newark, DE.
Deborah L. Long, Head of Objects Conservation
Gerald R. Ford Conservation Center, Omaha, NE.
Richard A. Corbett, Robert E. Tatnall, and Bradley K. Krantz
Corrosion and Materials Research Institute, Newark, DE.

    Three coatings commonly used for protection of silver artifacts
    housed indoor (Agateen, Paraloid B-72, and Paraloid B48-N) were
    tested to rank their performance. Protocols were developed to be
    relevant to conservation practice, while also incorporating
    industry testing techniques not commonly used in the
    conservation field. A variety of test specimen types were
    included to check for effects of complex geometry and sterling
    versus fine silver. Changes occurring on the silver beneath the
    coatings as well as changes of the coatings themselves were
    measured. Visual assessments provided qualitative data, while
    the use of electrical resistance atmospheric corrosion sensors
    and spectrophotometer measurements provided quantitative data.
    Accelerated aging included exposure to fluctuating temperature
    and relative humidity and to a variety of common pollutants.
    Both visual rankings and quantitative data were analyzed for
    statistical significance.

    Our results show that Agateen protects silver from any hydrogen
    sulfide exposure, even after great environmental stress, whereas
    the two acrylic coating are permeable to that pollutant. All
    three coatings begin to crack and peel slightly after
    accelerated environmental stress. For bent specimens with more
    complex geometry, brush application provides better protection
    from this environmental stress, preventing coatings from peeling
    away from edges For protection against hydrogen sulfide,
    spraying the coatings was sometimes more effective, perhaps
    because it may result in a thicker and more even coating.

    Our findings correspond with our field observations and the
    reported experiences of many conservators. Conservators are
    sometimes reluctant to use Agateen due to problems with other
    cellulose nitrate lacquers and to the severe degradation any
    cellulose nitrate can endure if exposed to very high
    temperatures or to direct sunlight. However, Agateen has
    preferable application and appearance qualities. Our research
    results support the continued use of Agateen for coating of
    silver for indoor environments.

    Inka and Colonial Period Qeros: A Collaborative Technical Study
    Ellen Pearlstein, Brooklyn Museum of Art; Brooklyn, NY; Emily
    Kaplan, National Museum of the American Indian/Smithsonian
    Institution, Cultural Resources Center, Suitland; MD; Ellen
    Howe, Metropolitan Museum of Art; New York, NY; Judith Levinson,
    American Museum of Natural History, New York, NY

    Ritual drinking cups known as qeros have been used for millennia
    in the Andean region and are still used today in traditional
    communities. Inka period qeros, usually unpainted but with
    intricate incised decoration, and Colonial period qeros with
    elaborately painted decoration, are widespread in art and
    anthropology museum collections. The art of painting qeros is
    widely considered 'lost'. The goals of this study are to
    identify the materials and methods used to create these vessels
    and to determine what these technical choices tell us about
    production.

    Conservators at four New York City museums are carrying out the
    current study using a laboratory protocol and survey form
    developed for this project. The four museums own a combined
    total of more than 150 qeros. Collaboration is multi-fold: in
    addition to the combined resources of our respective museums, we
    have scoured the works of the chroniclers for references to
    production, and consulted botanists, conservation scientists,
    art historians, and anthropologists in the US and in the Andean
    region. Museum professionals in Peru have allowed unique pieces
    to be sampled for analysis. Consultations with master artisans
    in Colombia have led us to a better understanding of the complex
    processes involved in the procurement of raw materials and
    preparation of the paint binder. On the basis of these
    investigations, we have been conducting replication experiments
    in the laboratory.

    Data from the chemical analyses and survey are being tabulated
    for a relational database. Results to date indicate that there
    was extraordinary uniformity in production and materials. All of
    the identified pigments are indigenous to the Andean region, and
    the resin binder has been traced to a plant found today in
    southwestern Colombia, on the northern frontier of the Inka
    empire. Significantly, the prehispanic materials and painting
    techniques continued to be used as long as these qeros were
    produced, well into the Colonial era.

The Hidden Secrets of Copper Acetates on Bronzes in the Athenian
Agora
Alice Paterakis, Head Conservator, Agora Excavations
American School of Classical Studies at Athens, Athens, Greece.

    Preliminary analysis indicates the formation of corrosion
    compounds containing copper acetate on copper alloy objects in
    the Athenian Agora.  Sources of acetate in the collection can
    include vinyl acetate, polyvinyl acetate, and cellulose acetate
    resins used as adhesives and lacquers in the past, acetic acid
    used for cleaning, ammonium acetate used in artificial
    patination, and wooden storage materials. Further studies of the
    corrosion products and synthetic polymers found on these
    objects, based on analyses carried out at The Metropolitan
    Museum of Art and The British Museum by XRD and FTIR, will
    illuminate the contributing factors in the formation of the
    copper acetates and the identification of the specific compounds
    present.

Desalination Parameters for Harappan Ceramics, Part 2
Harriet F. Beaubien
Smithsonian Center for Materials Research and Education (SCMRE),
Museum Support Center, Suitland, MD with
Tania E. Collas, Catherine E. Magee, Susan B. Peschken, Ellen F.
Rosenthal, Marie E. Svoboda, and C. Mei-An Tsu, and additional
contributions by Joanne M Boyer, Stephanie E. Hornbeck, and
Elizabeth C. Robertson.

    Background: On the basis of a pilot study and research design
    initiated during the 1994 field season [Holbrow, Katherine A.,
    Emily Kaplan and Harriet F. Beaubien, Desalination Parameters
    for Harappan Ceramics, Objects Specialty Group Postprints, vol.
    3, Proceedings of the OSG Session, 10 June 1995, 23rd Annual
    Meeting, American Institute for Conservation, St. Paul, MN, pp.
    70-76], a long-term study was implemented during the 1995 season
    at Harappa, Pakistan, to evaluate the damage caused by residual
    soluble salts in porous, low-fired archaeological ceramics.
    Since soil and water salinity are very high, and the volume of
    excavated material requiring desalination is enormous, this
    process places great strain on equipment, time, water and
    electricity, resources which are in short-supply. Thus, the
    initial question was whether the desalination process could be
    terminated leaving a *safe* amount of soluble salts, i.e., at
    levels that would not compromise the stability of these
    collections under standard storage conditions at the site.
    Substantial savings in resources might be realized if the
    process need not go as far as *zero*. Results from the long-term
    study and from related studies carried out at SCMRE since 1995
    would be used to evaluate and potentially modify the
    desalination protocols followed at Harappa's field conservation
    laboratory.

    The long-term study at Harappa. Damage trends after four years
    of 'real-time' aging will be discussed for samples of
    terra-cotta bangle bracelets, desalinated by daily change of
    distilled water baths in a 1:2 g:ml ratio, to various salinity
    levels as measured by the conductivity of the terminal bath. The
    initial study, using levels from *zero* to 400uS/cm (at
    increments of 100) and undesalinated controls, was expanded in
    1996 to include levels from 500 to 2000uS/cm (at increments of
    500), based upon results of an accelerated aging study on
    samples carried out at SCRME.

    Related studies at SCRME. Salt trends. Salts collected from a
    series of desalination baths were analyzed to investigate their
    pattern of release, as a possible guide to determining an
    appropriate desalination termination point.

    Water usage. Variations in g:ml proportions and the frequency of
    bath change (daily vs. equilibrium) were investigated to
    determine the most water-efficient method for reaching target
    conductivity levels.

    Conductivity correlations. Tests were carried out to investigate
    the issues of using conductivity measurements to describe
    solution concentration of different salt species.

    Results of these studies and implications for further
    desalination will be discussed.

Uranium in Glass, Glazes, and Enamels: History, Identification, and
Handling
Donna Strahan, Senior Objects Conservator
The Walters Art Gallery, Baltimore, MD

Uranium was used as a colorant in glass, glazes and enamels of
decorative and functional objects for roughly one hundred years
before the adverse effects of its radioactivity were understood. It
can be found in objects ranging from souvenirs, trinkets, everyday
dishes and glassware, to exotic one-of-a-kind artworks, decorative
lamps, and stained glass. Painted porcelain and enamels employed
uranium colorants because of their ability to withstand high firing
temperatures and because of the variety of colors they produced.
Colorants containing uranium have also been used in enamel
restorations.

Elemental uranium was first discovered in 1789. Between its
discovery as a colorant for glass/glazes in the 1840's, and the
identification of its hazards in the 1940's, uranium was extensively
used by the glass and ceramics industry, as well as by numerous
artists. It was particularly popular in the later half of the 19th
century in Europe, the United States, and Japan. Restrictions were
placed on the use of uranium in 1942 and it soon disappeared from
workshops.

The purpose of this paper is to bring the widespread use of uranium
in objects to the attention of practicing conservators and museum
personnel who routinely work with decorative and functional arts.
Whereas much work has been done on radioactive mineral specimens,
little has been reported on decorative objects. Those who are aware
of uranium as a colorant usually think of bright red-orange and
yellow glazes and glasses, but it is also used for dark-green and
black. Topics covered in this paper are uranium colorant
manufacturing methods, historical uses, detection and identification
methods, health risks and hazards, and suggested display and storage
methods. A balance will be made between understanding the hazards
and not over-reacting.

The Toxicity of Benzotriazole: Myth and Reality
Stephen P. Koob, Conservator, The Corning Museum of Glass, Corning,
NY

Benzotriazole, or "BTA", as it is commonly known, has been used in
conservation for over 30 years, both as an effective corrosion
stabilizer and as a corrosion inhibitor for copper and copper alloy
artifacts. Increasing rumors and un-researched references to BTA as
a carcinogen have unfortunately damaged its successful reputation.

This paper documents the history of BTA, as used in conservation,
and traces the origin of the carcinogen suspicion and the concern
over its toxicity.  Both early and recent studies indicate that
there is no evidence that benzotriazole is carcinogenic. Examples
and recommendations for the proper use of BTA as a dry chemical and
in solution are presented, along with a list of handling precautions
for solution preparation and application.

Any questions or comments please contact

    Emily Kaplan (1999 OSG Program Chair)
    National Museum of the American Indian/Smithsonian Institution
    301-238-6624 x6316
    Fax: 301-238-3201
    ekaplan [at] ic__si__edu

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                  Conservation DistList Instance 12:91
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