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June 22, 2015

On the Inka Road: Conserving an Incensario

This ceramic (NMAI 20/6313) is one of approximately 150 objects within the exhibition The Great Inka Road: Engineering an Empire, opening at the National Museum of the American Indian in Washington on Friday, June 26. This object, called an incensario, is from the Tiwanaku culture in the Katari Valley of Bolivia and dates to AD 600 to 900. 

Incensarios are incense burners or lamps, often associated with mortuary practices. Tiwanaku incensarios are characterized by their hyperboloid shape; scalloped rim; zoomorphic head and tail depicting a feline, condor, or llama; and elaborate design motifs, which portray geometric designs, feline faces, condors, and other beings of symbolic significance. 

Incensario 1 Incensario 2

Left to right: Tiwanaku incensario (incense burner, NMAI 20/6313), recto (front) and verso (back) before treatment. 

This incensario with feline head and tail and feline and condor design motifs was poorly reconstructed at some point before entering the collection of the Museum of the American Indian, now Smithsonian's National Museum of the American Indian. Sherds were misaligned, detracting from the ceramic’s beauty and detail. 

Incensario 3
Conservator (and blog-writer) Beth Holford cleaning the surface of the incensario with a soft brush.

In discussions with curator Ann McMullen and staff conservator Emily Kaplan, we decided that taking the ceramic apart and reconstructing it would enable the museum to present the incensario's original aesthetics without distraction. We anticipated that this process would take many hours in the Conservation Lab. Fortunately, I was able to start several months before the Conservation team began work on the rest of the objects for the Inka Road exhibition. 

Initial treatment included a surface cleaning and removal of old paint and fill material so that the adhesive holding the sherds together would be more accessible. Examination under ultraviolet light revealed an orange and white fluorescence, suggesting that at least one of the adhesives was likely shellac. Shellac can cause problems for conservators because it becomes less reversible as it ages. This was the case with this vessel, and it was necessary to use a mix of solvents as well as a paint stripper to soften the adhesive enough to deconstruct the ceramic. 

Incensario 4 Incensario 5Right to left: The left side of the incensario in visible light, then in ultraviolet light; the orange and white fluorescence was a clue that shellac might have been used to make earlier repairs. 

Once the ceramic was in pieces, I could remove the remaining adhesive residue mechanically— using a scalpel and working under magnification—so that the edges of the sherds were exposed and a more precise reconstruction could be accomplished. 

Incensario 6The object in pieces: all the adhesive has been removed from the ceramic.

Incensario 7

The vessel was reconstructed with a more conservation-appropriate adhesive—one that is chemically stable and readily reversible. Areas of loss were filled with a stable acrylic spackle. Select locations were painted with reversible acrylic paints in order to provide visitors to the exhibition with a more complete and aesthetically continuous appearance. 

These areas include locations where the original ceramic was missing, as well as locations where the slip design had been lost. Discussions with Ann McMullen helped identify areas of design that could be safely interpreted from similar designs on this vessel as well as others in this and other collections. Our goal was to preserve the incensario's cultural, historic, and aesthetic integrity, but we wouldn't mind if visitors were also thrilled by how wonderful it looks.

Incensario 8

Incensario 9
Incensario stages Tiwanaku-jaguar

Top right: Beth reconstructing the ceramic. 2nd row, left to right: The incensario before and after loss compensation and inpainting. 3rd row, left to right: The incensario before, during, and after treatment. Bottom row: The incensario as it appears in the companion book to the exhibition: Ceremonial incense burner in the form of a puma, AD 600–900. Tiwanaku, Bolivia. Ceramic, paint. 26 × 34.5 × 21.7 cm. Photo by Ernest Amoroso, NMAI. (20/6313)

—Beth Holford

Beth Holford is an independent conservator with Holford Objects Conservation, LLC.

Unless otherwise credited, all photographs are courtesy of NMAI Conservation.

The Great Inka Road: Engineering an Empire will be on view at the National Museum of the American Indian in Washington, D.C., from June 26, 2015, to June 1, 2018.



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