Art Conservation

Damage from squirrels to lead garden sculpture at the Winterthur Museum, Garden & Library occurred over several decades and was so widespread that almost every lead sculpture was relegated to storage to stop the problem. Within the last decade, many original lead pieces have been conserved and returned to the gardens. A cayenne pepper wax recipe has been employed as part of the annual maintenance program and so far has done the trick to deter squirrels. This tip presents the practical side of how to mix the wax, how to apply it, and what to expect in terms of its appearance and maintenance needs.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is quickly becoming a critical tool in the field of
art conservation. This technique provides high-resolution spatial maps of both inorganic and organic
components located within cross-sectional samples collected from works of art. With recent advances in
surface analysis, ToF-SIMS can now be used to identify specific amino acids present in protein-containing
materials as well as fatty acids in drying oils. For example, the detection of the ion fragment associated
with the amino acid hydroxyproline can be used to confirm the use of animal glue in a paint sample. As
an analytical technique, ToF-SIMS avoids the need for derivatization/silylation reagents, with no
interference by the presence of pigments. Furthermore, the layered systems that are often encountered in
historical paint samples remain intact throughout the analytical procedure. This allows for the colocalization
of organic and inorganic species in specific layers (e.g. egg yolk paint atop a glue ground).
Because of this ability to localize the analytical signal to approximately 6 μm or less, the mass spectral
information can be used to produce mass-resolved and spatially-resolve images which can be correlated
to previous studies of the same samples. In this study, ToF-SIMS was used to analyze a paint cross
section obtained from a painting attributed to Raphael, and another from a painting by the Sienese artist
Matteo di Giovanni.

The American Art Museum (SAAM) and the Pennsylvania Academy of Fine Arts (PAFA) worked collaboratively to research the materials and techniques of American painter Henry Ossawa Tanner (1859-1937) in preparation for the 2012 National Endowment for the Humanities funded exhibition, Henry Ossawa Tanner: Modern Spirit.  This ongoing project involves the technical analysis of several paintings from SAAM’s extensive collection of Tanner’s work and it is the first scientific appraisal of Tanner’s painting technique and materials.  The research project has contributed to exhibition materials that will provide an important new dimension to the story of Tanner as a black artist struggling to make his way in a harsh world – revealing him as a talented modern man whose training, intelligence and faith equipped him to surmount the difficult realities of his time and propelled him into a lifetime journey of personal and artistic discovery.

The Smithsonian American Art Museum (SAAM)
worked collaboratively with the Pennsylvania
Academy of Fine Arts (PAFA) to research the materials
and techniques of American painter Henry Ossawa
Tanner (1859–1937) in preparation for a 2012
PAFA exhibition – Henry Ossawa Tanner: Modern
Spirit. The initial phase of research involved the
technical analysis of several paintings from SAAM’s
extensive collection of Tanner’s work, with expanded
analysis on one of the most stratigraphically
complex paintings, The Fisherman’s Return. The
multiphase project is the first scientific appraisal
of Tanner’s painting technique and materials, and
the first comprehensive means of identifying and
resolving challenging aspects in the preservation
and conservation of Tanner’s work. The project
focuses on Tanner’s experimental use of materials,
recipes, and application techniques to produce
complex stratigraphy, texture, and visual effects in
his paintings so they can be identified and considered
during the development of new methodologies
and analytical means for treating his paintings.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is quickly becoming a critical tool in the field of
art conservation. This technique provides high-resolution spatial maps of both inorganic and organic
components located within cross-sectional samples collected from works of art. With recent advances in
surface analysis, ToF-SIMS can now be used to identify specific amino acids present in protein-containing
materials as well as fatty acids in drying oils. For example, the detection of the ion fragment associated
with the amino acid hydroxyproline can be used to confirm the use of animal glue in a paint sample. As
an analytical technique, ToF-SIMS avoids the need for derivatization/silylation reagents, with no
interference by the presence of pigments. Furthermore, the layered systems that are often encountered in
historical paint samples remain intact throughout the analytical procedure. This allows for the colocalization
of organic and inorganic species in specific layers (e.g. egg yolk paint atop a glue ground).
Because of this ability to localize the analytical signal to approximately 6 μm or less, the mass spectral
information can be used to produce mass-resolved and spatially-resolve images which can be correlated
to previous studies of the same samples. In this study, ToF-SIMS was used to analyze a paint cross
section obtained from a painting attributed to Raphael, and another from a painting by the Sienese artist
Matteo di Giovanni.

A versatile gel-like system for the treatment of art has been prepared from partially hydrolyzed poly(vinyl
acetate), borax, and large fractions of ethanol, isopropyl alcohol, n-propyl alcohol, and acetone. Variables
such as the concentrations of the two gelating components, the degree of hydrolysis and molecular
weight of the polymer, and the type of liquid gelated were investigated to establish formulations of gels
with physical and chemical properties that are best suited for specific applications. The gels were
designed to have an elastic character that allows them to conform to the topography of complex surfaces
and be removed with ease by being lifted from the surface. Results from fluorescence studies
demonstrated that the solvent is constrained within the area of the gel, allowing for localized treatment.
Polymer and boron residues were not detected after cleaning tests on acrylic and dammar test paint-outs,
and on two oil paintings with degraded surface coatings. The efficacy of the cleaning systems was
determined visually. Studies of the materials removed during treatments showed that the gels appear to
act by softening the coating surface while typically a pass with a solvent-dampened swab after gel
treatment removes the softened coating. Two case studies and notes on other applications of the gels are
described; recipes and preparation procedures are included.