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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 is unhelpful in establishing the date of the altar. Its presence, however, raises a number of questions: Was this layer used to protect the surface of the wood only until the current decoration was painted? Does this vermilion layer have a sacred purpose? Or was the altar in fact 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, but painted it red as this hue has consecratory implications.

Visible light photomicrograph of a paint cross section showing the altar’s two paint programs: early vermilion paint (1) and the current paint program with emerald green painted over red lead and a talc ground (2).




Current Paint Program (2)
The polychrome decoration that we see 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. Consequently, the visible, current paint program cannot predate the mid-nineteenth century.

Scientists identified the green paint on the altar
as emerald green pigment
[copper acetoarsenite; Cu(C2H3O2)3•3Cu(AsO2)2]
by comparing a Fourier transform infrared spectrum
of the paint to a reference spectrum of emerald green
pigment. Analysis by energy dispersive spectrometry
corroborated the identification by confirming the
presence of copper (Cu) and arsenic (As) in the pigment.

 

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