Tight, Aligned Joins Does Not a Sprung Vessel Make

In our first quarter class, CAEM 260: Structure, Properties, and Deterioration of Ceramic, Glass and Glazes, we were assigned a ceramic object on loan from  Southwest Museum of the American Indian Collection, Autry National Center to examine, document, and treat the following quarter. I was given a low-fired, light-colored Chiriqui vessel whose largest condition issue was its fragmentary state; the vessel was in 5 large fragments with additional small pieces in an accompanying bag (Fig. 1). As I would soon learn, assembling a broken vessel is not simply putting a puzzle back together and finding which pieces go where. The stress released as a vessel is broken can result in fragments that don’t quite meet up to complete the object as it was before—and I learned exactly how frustrating it can be to achieve tight and aligned joins with stubborn objects like this!

Fig. 1. A soon-to-be joined Chiriqui vessel, comprised of 5 large fragments and several small pieces. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 491.G.1524

 

Joining my vessel (with 40% Acryloid B-72 in acetone using a brush) went quite well in the beginning, such as with Fragments C and E  (Fig. 2).

Fig. 2. Fragments C and E prior to joining (a) and after joining (b); the resulting join was tight and aligned (c). Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 491.G.1524

 

I determined the best sequence would be to join Fragments C-E-A and Fragments B-D (Fig. 3).

Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 491.G.1524

 

These two sections would then come together to complete the vessel…however this didn’t prove to be as easy as I had thought. I found that while one side of the join was well aligned and tight, the other side by comparison was like a mile-wide fissure as far as I was concerned (Fig. 4); a jolting discovery for a newbie in training! The two sections just didn’t fit, despite careful and tight joining of the fragments that comprised them.

Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 491.G.1524

 

Any ideas I had about merely adding adhesive and piecing the vessel back together were naively simple and optimistic in hindsight, but fortunately lab manager and conservator, Vanessa Muros, was able to guide me through a more complicated (and at times scary!), multi-stage aligning method involving heat and pressure. The misaligned fragments were adjusted using a hair drier (set to a low temperature) to soften the B-72, and then pressure was applied using 3M Coban self-adherent wrap and soft-grip clamps, with barriers of thin Ethafoam and Volara (Figs. 5-6); slow tightening of the Coban wrap was performed regularly using a wooden popsicle stick. This process may seem simple, but pressure was required in multiple directions and aligning one area often caused another to move and misalign; all joins had to be considered. It became a battle over control between what I wanted the fragments to do and how they naturally wanted to be, all while gauging the safety of the object and determining when enough was enough.

Figures 5-6. Alignment of the joins. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 491.G.1524

 

In the end, relatively good joins were achieved overall (Figs.7-8). The changes that occurred from the stress released upon breaking still prevented perfectly tight and aligned joins everywhere, but the best compromise was achieved and the results were more than satisfactory. I was able to learn about the unforeseeable problems that can occur during the treatment of ceramics, and I gained a greater feel for the material and how it behaves…and I’ll be ready for the next one!

Figures 7-8. Vessel after treatment. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 491.G.1524

by Heather White (’16)

Conserving Nayarit Ceramics

Last quarter we both had the opportunity to treat pre-Columbian Nayarit ceramic figurines from Mexico, on loan from the Southwest Museum of the American Indian Collection, Autry National Center. At first glance we thought the treatment would be pretty straightforward, but after a closer look it appeared to be anything but!

The surface and structure of the figurines are deceptively highly restored, which can be common for artifacts passing through the art market. In addition to reassembling the fragmented figurines, our goal is to document and identify old from new, and shed light onto the unknown pasts of these objects. We’re approaching the project with a range of tools including X-ray imaging, UV-induced visible fluorescence imaging, X-ray diffraction (XRD) analysis, and X-ray fluorescence (XRF) spectrometry. XRF analysis indicates the presence of lead and zinc on the surface of both figurines, which are common in modern pigments, though typically not found in pre-Columbian ceramics. Using XRF and XRD, we also detected the presence of plaster in some areas, a common restoration material for ceramics. While we work to try to piece our puzzles together, take a look at our projects!

Female Nayarit figurine before treatment. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 2232.G.33

Female Nayarit figurine during treatment: after reconstruction (left) and after gap-filling of the joins to stabilize fragments on the nose and lower section of the body (right). Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 2232.G.33

Female Nayarit figurine after treatment. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 2232.G.33

Figure 5: Male Nayarit figurine, imaged under visible light (left), 415 λ induced visible fluorescence (center) and B&W image of UV induced visible fluorescence (right). Fluorescence imaging can help distinguish difference in material that cannot be detected under normal lighting conditions. It is common for restoration materials to fluoresce distinctly from original material. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 2232.G.28

X-ray image of Male Nayarit figurine taken from the back of the object at 45 kV. This imaging technique reveals that the body is composed of many fragments that have been previously restored. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 2232.G.28

XRF analysis was conducted on the rear supports at the bottom of the figurine. The spectrum shows presence of gypsum-based plaster due to the high calcium peak (CaKa1) and presence of a sulfur peak (S Ka1) indicating this is an area of restoration. The significant amounts of titanium (Ti Ka1) and manganese (Mn Ka1) may be from modern pigments used to paint the plaster surface. Southwest Museum of the American Indian Collection, Autry National Center, Los Angeles; 2232.G.28

Colette Khanaferov and Betsy Burr (’16)