Selected Case Studies

Endangered Animal? Assessing the Light Sensitivity of Walton Ford’s “Oso Dorado”

Works of art on paper are often subject to irreversible light-induced damage, a dilemma for institutions that wish to both display the works to the public and preserve them for future generations. A large modern watercolor, Oso Dorado by Walton Ford, was acquired by the Museum of Fine Arts, Houston, at “One Great Night in November 2013,” the same year the painting was created.

When the work is so new, it is in a pristine, unfaded condition. A conservative approach to preserving it in this state would be to carefully regulate its light exposure by controlling exhibition light levels and frequency. The Museum uses an established set of exposure guidelines that are successful at preserving works of art on paper; however, they are not necessarily the optimum for any single work and limit how often an object can be on view and enjoyed by the public.

In the 1990s, Paul Whitmore, a scientist at Carnegie Mellon University, created an instrument known as a microfade tester that uses a very small (0.4 mm) and very intense beam of light to slightly fade an area of color in a work of art. The fading rate of the color is compared to the fading rate of three different swatches of blue-dyed wool whose light sensitivity is known. This comparison allows scientists to predict how much light a work of art can be exposed to before beginning to fade.

The MFAH does not own a microfade tester. However, a neighboring institution, the Menil Collection, does. The two institutions agreed to collaborate, and Oso Dorado was transported from the MFAH to the Menil, where MFAH paper conservator Tina Tan and Cory Rogge, Andrew W. Mellon Research Scientist at the MFAH and the Menil Collection, tested the lightfastness of 12 different areas of Oso Dorado. All of the colors tested showed relatively gradual rate of fading, indicating that the artwork is stable. Rogge further analyzed pigments in Oso Dorado with X-ray fluorescence spectroscopy and confirmed that the artist used watercolor containing inorganic pigments, including cadmium red, cadmium orange, cadmium yellow, umber, bone/ivory black, iron earth red, iron earth yellow, carbon black, titanium white, zinc white, calcium carbonate, and barium sulfate. This information helps the conservators and curators decide how long, under what light levels, and how often Oso Dorado may safely be exhibited.


The Ceramic Robotics of Clayton Bailey

California artist Clayton Bailey has devoted his career to comedy, science, and pseudoscience through the medium of ceramics. His 1977 work Monster ("Burping Bowl"), part of the Eagle Collection of contemporary American decorative arts at the MFAH, is a cross between a pond-dwelling sci-fi monster and the childhood nightmare of someone living in the toilet bowl. A head rests in a bowl of water, and air is pumped under the cavity of the head by an aquarium air pump. When enough air builds up, the head lifts up in the water and releases the air with a burp.

When the object came into the Museum’s collection, it had been separated from its original pump, and it was unclear where the water level should be. The short piece of plastic-covered steel wire used as a hinge to affix the head in the bowl was significantly corroded and deteriorated. Additionally, there had been some damage to the bottom edge of the head, which—although not visible when the object was assembled—could potentially affect the working sounds of the object. Garden debris had soiled the surfaces of the object, and the copper tube that allows air to be pumped into the interior of the head had been blocked with soil. After cleaning, a new pump and a new piece of copper electrical wire for a hinge were purchased, and the object assembled. Through experimentation, a variety of sound patterns could be produced, largely dependent upon water level. The sharp sound of ceramic against ceramic was determined to be undesirable, and a few dots of latex-silicone were added to places where the old silicone cushion had been lost. 

When the water level was higher, the burp was louder and longer, and the intervals between burps longer, whereas lower water levels produced burps smaller and more frequent, with a sound more akin to a burbling fountain. Given the artist’s predilection for objects eliciting shock and amusement, the first was more likely to be his preference. However, larger burps produced a larger radius of spray, which would constitute a slipping hazard for visitors. A middle ground of moderate burps and minimal spray was decided on for displaying Monster ("Burping Bowl") in the exhibition Beyond Craft: Decorative Arts from the Leatrice S. and Melvin B. Eagle Collection.


Illumination in the Lab

Espaces Chromatiques Carrées en Spirale, a 1968 kinetic sculpture by Gregorio Vardánega, an Argentinean artist working in Paris, consists of 6 white, painted plywood panels illuminated by 63 small light bulbs, set into a black box. A third of the bulbs are covered with red plastic cylinders and a third with blue, leaving a third uncolored. A vintage electronic component designed by the artist drives the illumination of the bulbs in a complex sequence, creating a vibrant dance of colors and patterns.

During examination in preparation for the MFAH exhibition Constructed Dialogues: Concrete, Geometric, and Kinetic Art from the Latin American Collection, it was discovered that 49 of 63 of the bulbs did not light up. As sometimes corrosion on the metal connections can cause old, little-used bulbs to fail, even though they are not yet dead, the first treatment attempt was to remove the bulbs, clean the connectors with an abrasive nylon pad, and try again. Unfortunately, the situation did not improve—the bulbs were, indeed, dead.

It is a general principle of conservation that original material should be preserved at all costs, which sometimes means that change in the appearance of an object must be accepted to maintain its essential authenticity. However, in the case of electronic, kinetic, and light-based art, it may also be said that if these elements are not working, the object no longer exists. Preservation of the artist’s essential idea and vision therefore becomes far more important than the preservation of the original material. New, working bulbs are more authentic than original, non-working bulbs.

After considerable search, dead stock vintage light bulbs of the same shape, wattage, and voltage were ordered from France. It was essential that the glass dome be the same shape, despite not being visible to the viewer, because there was a risk that a larger shape might bring the heat of the bulb closer to the colored plastic sleeves and deform them. All 63 bulbs were replaced to ensure a homogenous appearance (although no difference in the quality of light between new and old bulbs was visually discerned) and to ensure a consistent electrical load.

Sometimes conservation is as simple as replacing a light bulb.


 


The Prints of Antonio Berni

Argentinean artist Antonio Berni coined the term xilo-collage-relief, a combination of traditional woodcut and collagraph printmaking techniques, to define his high-relief prints made during the 1960s and 70s. Berni’s working method consisted of first incorporating carved wooden blocks with other elements, such as coins, metal hardware, and molds made of dental plaster, to build a collage, and then sealing the plate with varnish or lacquer to keep it from sticking to the printing paper. The paper sheet was soaked in water for 15 to 20 minutes to soften it before it was pressed and molded into the negative space of the plate. In areas of high relief, the paper would sometimes break, requiring Berni to add “patches” of paper with glue onto the verso. Paper fibers were sampled by MFAH conservation scientist Corina Rogge and identified as primarily chemically processed wood pulp, which explains why the fibers are short and prone to breaking. Once the sheet was dry, Berni would stuff the verso of the print with sawdust and cover with layers of rubber and felt to create a flat plane for additional pressing and inking. In total, the print was re-registered and pressed up to 4 or 5 times, resulting in an image made up of black ink background and cream paper highlights. The colored inks were likely hand-applied as a final step to the process.[1]

Working with Berni’s xilo-collage-reliefs during conservation and framing posed a unique challenge since most works on paper are two-dimensional and ink is often the only material raised from the surface. In order to flip these prints over for photography or treatment, blocks were built from stacks of blotter paper and rigid polyethylene foam to raise the corners up to the same height as the relief. The majority of conservation treatment was needed to address previous housings that were causing the paper to become brittle and discolored. Steps included removing the prints from acidic substrates, like Masonite and foam-core board, cleaning the surface with block erasers, and reducing tape and synthetic adhesives using a combination of mechanical action, heat, and solvents. One print was nailed directly to its frame and the nails had to be pried out with a metal spatula before the holes could be mended with Japanese paper and wheat starch paste. In order to re-frame the pieces for display, window mats were constructed with multiple laminates of matboard (up to 1 ½ inches) to keep the glazing from touching the print. Each print was then sealed around the back and sides with Marvelseal aluminized nylon and polyethylene barrier film to provide protection from water vapor, pests, pollution, and other environmental factors and, finally, fit into a new frame.

The ultimate goal of conservation and framing was to restore the prints to their original intended appearance using preservation-minded materials and techniques. The resulting artworks are considerable in weight and dimensions, but now these 66 high relief prints are ready for display and long-term storage.


[1] Antreasian, G. 1979. 3 Argentine printmakers: styles and techniques at the Latin Print Triennial. Print News 1(6): 8–9.


A Study of Pigments

Kamisaka Sekka (1866–1942), foremost among Japanese “designers” of the early 20th century, was a prolific creator in numerous media, including paintings, lacquers, textiles, ceramics and printed books. Venerated as a legitimate successor of the Rimpa tradition later in his career, Sekka demonstrated the stylistic transition from his early Shijō school training of lyrical realism to the decorative Rimpa style in a series of polychrome woodblock prints published monthly by Unsôdô (Kyoto) between February of 1899 to June of 1900. A total of 54 prints were later complied and bound into 3 volumes titled Chigusa (A Thousand Grasses), likely between 1900 and 1905.
 
A complete three-volume set of Chigusa entered the collection of Museum of Fine Arts, Houston (MFAH) in the fall of 2010. Metallic colors are used in many prints to achieve lavish visual effects. While the prints are in good overall condition, some discoloration of paper and metallic surfaces has occurred on areas of prints that are in direct contact with areas of metallic pigments on facing pages. Although publications on techniques and materials related to traditional Japanese woodblock prints (ukiyo-e) are available to the English speaking audience, technical studies on post Edo era (1603-1868) woodblock prints are scarce.

Conducted in 2011 and 2012 by MFAH conservation scientist Anikó Bezur, MFAH paper conservator Tina C. Tan, and Nicole Garcia from Rice University, this research represents the early results of the examination and analysis of pigments used in bound as well as unbound versions of woodblock prints in this Chigusa series using non-destructive techniques, including optical microscopy, digital infrared reflectography and x-ray fluorescence spectroscopy (XRF.) Visible light microscopy was essential to establishing the application sequence of various colors, thereby aiding the interpretation of elemental analysis results obtained using XRF. Elemental analysis revealed the use of chrome yellow and unusual metallic powders in addition to inorganic pigments identified in published studies of late nineteenth-century ukiyo-e prints. Differences were noted in the choice of pigments used in executing bound and unbound versions of the same prints.


Virgin and Child

Antonio Vivarini's devotional image Virgin and Child (c. 1440) was originally painted with traditional methods including a gessoed panel, water gilding and punchwork, tempera paint layers, and oil gilding details. Over time many changes have occurred. Almost all of the oil gilding has worn away altering the rich appearance of the Virgin’s robe and centuries of dirt were caked into the delicate gold background. Most significantly the original wooden panel was entirely removed in the 1970s. As the wood aged it began to shift causing cracks in the painting. Efforts to stop this process were unsuccessful and eventually the only millimeters thick painting was painstakingly transferred to a new modern honeycomb panel.

Over the past two years at the MFAH, the painting has undergone another treatment. For probably the first time since it was created, the punchwork was meticulously cleaned using eye surgery scalpels under a microscope, bringing renewed brilliance to the gold details. In the past the edges of the panel were extended, changing the shape of the base of the throne. Before the most recent treatment the perspective was too high, causing the Virgin and child to appear to tip out of the picture plane. This area was reworked without covering any original paint, to more closely match what would have been the composition of the artist. Many of the damages were minimized and the delicate glazes recreated; this allows the viewer to focus on the image as created by the artist, rather than the alterations created over time.