Case Study: Tibetan Altar

In 2004, the museum acquired a spectacular Tibetan altar adorned with intricately carved niches and lively paintings that highlight domestic themes. However, this altar arrived at the museum covered by a thick layer of soot—a result of countless burnt offerings—and disassembled into seventy-six pieces.

An extensive conservation project was launched to reconstruct the altar, create a stable and non-intrusive structural support, reveal the brilliant colors and artistry beneath the grime, and explore the age of the piece as well as the artists’ materials and techniques.

Funds to conserve the altar were generously provided by the Women’s Committee of the Philadelphia Museum of Art and the Samuel H. Kress Foundation.

Structural Stabilization

The altar was originally built into the walls of a Tibetan home, so to transport it, the altar was disassembled and removed from its original support. At the museum, the doors, panels, drawers, and cabinets were reassembled. A replacement framework was engineered, guided by the patterns of soiling and remaining wooden joinery, and was then attached with tenons slotted into the mortises of the altar. No glue or screws were used, in keeping with the original construction method. Part of this new framework can be seen in the photograph.

Treatment of Painted Surfaces

First, flaking paint was re-adhered to the wood surface with a custom glue. After this paint was stabilized, the remaining painted surfaces were cleaned to reveal brilliant colors that had been obscured by soot and grime. In Tibetan-Buddhist practice, the soot is considered a by-product of burning offertory butter lamps and thus there are no cultural objections to its removal. The rich variety of hues and designs that were uncovered allowed the museum to more fully appreciate the Tibetan-Buddhist aesthetic, the patron’s intent, and the artisans’ skill.

Painting Materials

The brilliantly colored decorations on the altar were created using gilding, distemper paint (pigments suspended in animal glue), and raised decorations called khyung bur in Tibetan.

Gilding

Gilding, the process of applying thin layers of real gold to an object’s surface, is a favored method of decoration. On this altar, less costly metals such as tin (a white metal) and brass (a yellow alloy of copper and zinc) were manipulated to imitate gold, with tin being used for the majority of the gilding. To make it appear golden, the tin leaf (such as that found on the raised khyung bur) was tinted with an oily mixture of turmeric, saffron, and other yellow colorants. Brass flake and brass leaf can be seen in subtle contrast with the tin leaf on the breastplate of the protector deity on a door of the right-most upper cabinet.

Pigments

A variety of synthetic and natural pigments were used to create the altar decorations. For example, on the upper leftmost door panel depicting the pair of cranes, the dominant background color utilizes red lead. Other contrasting pigments include emerald green (in the pine tree needles and the bird feathers), and lead white outlined with indigo (in the water). The entire scene is framed with stylized lotus flowers and scrolling vine patterns colored with emerald green, orpiment (yellow), and ultramarine (blue). Tibetan color theory revels in the use of alternating layers of colors, as seen in the varying shades of yellow and orange in the lotus petals.

How Old is the Altar?

The two distinct painted decorative schemes discovered on the altar provide clues to its age. Based on scientific examination of the paint, the current polychrome decoration dates from the mid-nineteenth century at the earliest, but a lower vermilion (red) paint layer and the wood construction of the altar may be older still.

Earliest Paint Program (1)

The vermilion paint layer (now hidden) is extremely thin and covers the entire altar. Because vermilion is found on many early artifacts, it doesn’t help establish the date of the altar. Its presence, however, raises a number of questions: Was this layer used to protect the surface of the wood until the current decoration was painted? Does this vermilion layer have a sacred purpose? Or was the altar intended to be uniformly red? Perhaps it was originally commissioned by an older generation of patrons who lacked the funds to more elaborately adorn the altar, and painted it red since this hue has consecratory implications.

Current Paint Program (2)

The polychrome decoration seen today contains many vibrant pigments, including synthetic ultramarine and emerald green. Emerald green was first produced in Germany in 1814, while synthetic ultramarine was first made in France and Germany around 1830. These and other man-made colorants were brought to Asia through European trade and by 1885 were a significant influence on the color aesthetics of Tibet, which means the visible paint program does not predate the mid-nineteenth century.

Four of the thirty-nine vase panels in the center of the upper portion of the altar are different in color. Conservators investigated their anomalous appearance using X-radiography, which revealed that two panels have a hidden, underlying lotus blossom design (Figure A). The discovery of the underlying paint shows that the panels were fabricated from another painted wooden artifact with a matching lotus design and then repainted to match the vase panels on the altar. Most likely, these panels were recycled from another piece of furniture, since wood is scarce in many parts of Tibet.

The other two anomalous panels also appear to be replacements but are actually original to the altar (Figure B). Their original decoration matches the design and paint composition of the other vase panels, but was covered over by modern polyvinyl acetate paint and glittery mica gilding (possibly to disguise damage). A faux dirt layer consisting of charcoal and resin was applied to the surface of the paint to mimic the patina (or aged appearance) of the altar. In the conservation treatment, these newer materials were preserved as part of the history of the altar.