Tag: AIC’s 44th Annual Meeting

Madeleine and Nancy presented a very interesting talk that shared their experiences using cold temperatures to achieve a specific treatment goal. Nancy began by introducing the object, a Lakota Winter Count. The object is one of a type of pictorial calendars that depict the history of the community and serve as a counting device. A historian would have been in charge of the count, naming years for remarkable events related to astronomy, the environment, or culture. Tribal keepers knew the name of the years, helping them to recall the oral history of the community.
The Lakota Winter Count that inspired this talk is from the Heard Museum in Phoenix, Arizona. At some point in the past, it had been folded so that the pictograph surface faced out. The interior surface had become stuck to itself, preventing the unfolding of the object. As the Heard Museum does not currently have a permanent conservation staff, the object was brought to the Arizona State Museum for treatment.
The primary goal of treatment was to unfold the count, enabling the viewer to see all of the pictographs at the same time. Additionally, there is bleeding, mold, darkening, and tears on the support. There was no history of fabrication or provenance associated with the object so the Arizona conservation team undertook documentation and investigation.
There are 121 pictographs on the non-coated side of the support that documents the years 1799 to 1918. The outlines are drawn in graphite and the limited additional pallette is consistent with other winter counts. These include two browns, a bright pink pastel, and blue and orange colored pencils. Specifically, the Heard winter count is very similar to a Long Soldier Winter Count at the NMAI. Sometimes, duplicates of counts were made for use or for sale, which could explain the similarities of the two pieces that cover roughly the same period. The Heard count is likely from a similar region in North Dakota.
The object was analyzed and the support was determined to be a piece of commercial oilcloth. FTIR showed the oilcloth coating is linseed oil and shellac. Fiber samples taken indicate that the fabric is cotton. This is consistent with commercial oilcloth produced in the late 19th, early 20th century; during this time period, commercial products began to replace local materials. Maker’s marks on the oilcloth identify the manufacturing company and Nancy and Madeleine shared contemporary advertisements, which demonstrated the prevalence of the product in the average household. The mark gives a terminus post quem of after 1901.
The fusing of the oil cloth to itself was likely due to ambient heat. A 1-2 cm opening along the edge was the maximum access before treatment. Dave Smith, conservation scientist at Arizona, was able to determine the glass transition period of the oilcloth coating is approximately 31⁰C. The average temperature in Arizona exceeds this from April to October, so the environment could have caused the shifting in the structure of the materials that led to the current sticking.
Madeleine undertook testing to explore options for opening the count. Organic solvents were not effective as the coating is cross-linked and now impervious. At this point, it was clear that whatever treatment was applied would be time consuming and invasive. The conservators asked the curators how crucial the treatment was to the object; however, the curators said that the current condition was fundamentally comprising the interpretation of the object as the chronological reading of the object was disrupted.
Knowing this, the conservators went back to the drawing board. Dave suggested considering cold temperatures, because polymers are long chain molecules whose movements are highly linked to temperature. If the temperature is below the Tg, then the polymers can no longer stretch and instead cleave, allowing for the two sides to be separated. Conservators tried compressed cooled CO2 gas, which was not effective. Similarly, overall freezing works at first, but the object warmed up too quickly for this to be viable for treating the whole object. Next, they used a Peltier cooler to apply repeated cold in a smaller area. The team worked to retrofit a USB beverage chiller to be able to consistently apply a 5⁰C. This system was used by applying the cooling plate to oilcloth surface for three minutes, then lifting the device so that Madeleine could use a stainless steel spatula to cleave small sections of the cloth from the opposite surface. She continued in this way for three months, working on the project for portions of each day.
After the cloth was opened, treatment turned to the tears, some of which appear to be linked to earlier attempts to force open the oilcloth. Stitching the tears was not viable because there was no safe place to secure the tears given the nature of the oilcloth. Adhesive backings also were not expected to be successful, as they would likely curl away from the coated surface over time. Instead, Madeleine found that by applying granules of textile welding powder to individual warps and wefts, she could control her mends and allow for a degree of reversibility. This process required four steps: relax the creases using Gortex, Dartex, and weights; pull misaligned fibers back into place; reweave fibers where possible; and, apply the granules of adhesive. The granules were heated in situ to a temperature at which they began to soften but did not completely solubilize, so that individual granules could then be mechanically removed if necessary. In some places, a secondary support was added where there were not enough wefts or warps. Small pieces of Remay were torn to the right shape, toned with dilute acrylics, dusted with the welding powder, and heated between silicone release paper in place.
Thus, the treatment presented benefited from the use of both low heat and cold temperatures. It was highly time intensive; however, this was considered justifiable as the object was a special project. The speakers also encouraged conservators to consider the use of cold for other treatment applications, as it seems to be underexplored when compared to higher temperatures.  
After the presentation, one question was asked:

1. Q: Why did they not just heat the oilcloth coating to past the glass transition temperature? A: Doing this would likely have caused the cloth to become more sticky, more bonder, and more flexible. When the polymers are cold, they want to break due to the brittleness. The weakest point of contact in this case was with the other side, so cleaving the polymers facilitated the treatment goal.

 
This post was written from my personal notes, which may contain errors or inaccurately represent the author’s original intentions.

The Aftermath of Mends: Removing Historic Fabric Tape from Tlingit Basketry, presented by Caitlin Mahony and Teri Rofkar
The talk began with an introduction from Teri, who reminded us to be thankful to the caretakers of the land in Montreal. She and Caitlin then shared their presentation of a Mellon fellow project at the National Museum of the American Indian on removing a series of historic mends from Tlingit basketry. This project served as an opportunity to “reactivate” the baskets in their collection.
Teri read from a book entitled for Healing Our Spirit, sharing a Tlingit Oratory which advocated us to “apply kindness to open wounds,” an interesting perspective on the state of the baskets prior to conservation.

After seeing the image above of one of the first mother baskets, the audience was introduced to the history of Tlingit basketry. The primary material of these baskets is spruce root, some of which is dyed. Originally constructed as functional objects, they were eventually woven for the tourist trade, which helped the community transition from a subsistence to a market economy. When in use, Teri mentioned the baskets could be expected to have approximately a 100 year life span given heavy use.
There are now over 700 Tlingit baskets in the NMAI, many of which suffer from condition concerns. These include rips, tears, losses, and fold lines. Patterns of damage indicated that the dyed spruce root regions may be contributing to weakness. In 2011, the NMAI hosted a Mellon fellow research project that investigated the processing of spruce root at a cellular level. This set the stage for the more recent project which was focused on treatment.
In the first half of the 20th century, a repair campaign on pottery in the NMAI collection was documented. An image shared in the lecture showed a row of gentlemen seated behind a table covered with ceramics. A similar campaign was likely undertaken with the Tlingit baskets, though there is no documentation. Most of the repairs used hide glue or cellulose nitrate impregnated fabric strips that were painted with oil paints. Either the colors were never close matches or they have shifted significantly with time, but the repairs are currently aesthetically incongruous.
Of the 580 baskets investigated, 130 had historic mends. Of these, 24 had major repairs, which was defined as 20+ mends or a mend that obscured a sizable area of the wall or base. Tears were frequently found adjacent to these mends, likely due to the greater strength of the adhesive than the basket. Distortion was also noted, likely due to the effects of the drying of the adhesives. They also caused the removal or redeposition of tannins, dirt, and residue from the baskets, resulting in tide lines.  Given the current condition, many of the baskets could not be exhibited, studied, or handled. Thus, the baskets were ‘inactive’ and no longer serving either their original or adopted functions.
NMAI hosted a three-day conservation workshop in April with representatives from museums with strong Tlingit basket collections. One goal of the workshop was to form an integrated protocol, as well as to study the technology and develop action points to create a path forward.
Since the workshop, NMAI has undertaken extensive documentation, consulted with the Tlingit community to correct and confirm catalog information, identified the wrapped weft material, which had been called false embroidery, and created digital reconstructions. These computer-generated images were created by Laurie Stepp and illustrate how the baskets would have looked when new. They also analyzed the color values, as the tannins are oxidizing and the dye fading.
After processing this information, experimentation was undertaken to develop a treatment approach. The primary goal for the baskets with major repairs involved taking down the fabric mends. Mockups provided by the Getty were used to test various methods. First focusing on the hide glue repairs, Caitlin found that water caused tide lines and blanching when applied with less control. However, when applied in the form of 2% agarose gel, the adhesive was softened and no tide lines formed. This approach was then used in treating the baskets. No barrier layer was necessary and they could work in multiple locations at the same time. They covered the agarose with plastic and gently weighted the gel to reduce evaporation and improve contact. Caitlin found a dwell time of approximately 45 minutes was effective. The fabric tape and residual adhesive could be mechanically removed with wooden skewers in the direction of the stitches; no adverse effects were noted from the treatment.
However, once the fabric was removed, areas of basketry were revealed whih had been protected from light exposure, indicating what the colors may have looked like when the baskets were first collected. This brought up the question of the aesthetic reintegration of the areas of previous repair. Conservators discussed this with curators and considered what the baskets might gain and loose through reintegration. The repairs are part of the baskets’ stories, but they are also visually distracting. This is an ongoing conversation.
Storage was designed for each object, based on individual needs and condition concerns.  NMAI is also exploring how to improve access to this collection. They want to ‘reconnect the disturbed baskets’, and are currently loading tablets with the images and information which can be distributed to schools and used for other programs. An ongoing goal of the project is to continue collaboration between institutions to facilitate knowledge sharing. The NMAI also wants to connect with the contemporary weaving community, which Teri described as fragile, explaining that there were not many weavers 100 years ago and that there are even less now. Contemporary weavers work on commissions – so let’s ask people to weave again!
The talk ended with Teri saying, ‘Gunalcheesh, Ho, Ho. Thank you from the bottom of my heart.’ With this, she extended gratitude to the baskets and the remarkable women who wove them.
After the presentation, two questions were asked:

1. Q: Did NMAI find any traditional repairs?  A: Yes, which included the weaving of new spruce roots, the combination of parts of baskets, such as the bottom of one with the walls of another, and the repurposing of large baskets to extend their lifetime.
2. Q: The agarose gel approach worked for the hide glue, what about with the cellulose nitrate mends? A: No, agarose did not work and acetone has negative effects on the baskets. They plan to try saturating the areas with D3/D4 silicone solvents to mask the materials and create a dam, but this is an aspect of future work.

This post was written from my personal notes, which may contain errors or inaccurately represent the author’s original intentions.