Category: Objects Conservation

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.

This talk focused on the research and treatment of Froment-Meurice oyster shell artifact made by Emile Froment-Meurice.  The conservation concerns were identification of the corrosion layers and treatment of the metal surfaces.   The artifact was purchased by William Walters in 1878.  It is a composite artifact that depicts two putti discovering a pearl inside of an oyster.  The oyster shell holds a natural pearl in a metal mount.  The mermaid stem and putti are a silver copper alloy, the base is silver with a gold enriched surface and the hinge is a gold alloy.  The oyster shell artifact was damaged and repaired multiple times in the past.  The 1930 photograph from the museum shows the object in one piece.
The main condition issue for this treatment was the heavily tarnished metal surfaces.  The silver and gold elements were nearly black with heavy tarnish overall.  In the 1840s the goldsmiths would often intentionally create a darkened oxidized surface on silver.  In a 2003 French catalogue “Tresors D’Argent” (translated as “Silver Treasures”) two similar shell objects are included, but both have polished and shiny metal elements.  Other artifacts are listed as “oxidized silver and painted sheet metal” objects.  A similar oxidized silver surface can be found on the commemorative shield (c. 1881) by Froment-Meurice in the Art Institute of Chicago labeled as “an elliptical shield of oxidized silver”.
There are a few differences between tarnished silver and oxidized silver.  Tarnished silver is an unintentional patina created by airborne pollutants.  Oxidized silver is an intentional antiqued patination created by chemical compounds.  The small traces of silver chloride found on the surface of the artifacts may be a byproduct of silver chloride that was used to antique the surface of silver objects.  With this in mind, the decision was made to clean the silver, but not remove the black surface.  The gold elements would be cleaned until bright.
The gold and gilt silver components could not be cleaned with abrasion or normal polishing.  Instead an acidified thiourea xantham gum gel was used to clean the surface.  The gel as applied with a cotton pad and rinsed with water.  The dwell time was kept to a quick 5 – 10 seconds.  The process was repeated as needed.  For the metal clasp, mylar was placed between the metal and the shell to protect the surface of the shell.  The gel was applied with a brush and then rinsed with the use of chem-wipes and a bristle brush.  The gel cleaning produced a bright and shiny surface.  The process had excellent control and a quick removal of the material was possible.  The putto were adhered into place, but the shell was left partially unassembled for transportation.  A complex and well-designed storage and shipment box was created for the artifact.  This storage box was featured in the STASH flash III on May 14^th and will be published on the AIC STASH website.

Elizabeth La Duc gave an engrossing talk in the Objects Specialty session on the conservation treatment of a 19th century Pietre Dure and micromosaic tabletop belonging to the Josiah Quincy house of Historic New England. The stone tabletop, positioned on top of a painting and gilded wooden base, had and been conserved in the past.  Her treatment was readdressing this past treatment and returning it to exhibit-able condition.
Pietre Dure translates into English as “hard stone”.  The Pietre Dure portions consist of decorative stones set into the carved channels within the black marble base and adhered with a rosin and beeswax.  The micromosaic areas are images made up from tiny tesserae called smalti.  The smalti are cut to shape and inserted into an adhesive of linseed oil, lime and marble dust.  The top surface was polished to a flat surface and the gaps between the tesserae were filled with tinted beeswax.  This beeswax can be seen under ultraviolet light, but it has often been lost through over cleaning and use.
The table top was in poor condition.  The four sections were poorly adhered and slightly misaligned.  A large crack in the stone tabletop ran across the middle of the tabletop and transected both the Pietre Dure and the micromosaic elements of the table.  Two stone inlays were missing and there were losses in the micromosaic along the central break.
The conservation treatment started with a surface cleaning of calcium saturated water with the pH raised to 8.5 with ammonia and added drops of Triton.  Acetone was wicked into the old joins to dissolve the older restoration adhesive.  B72 and microballons were used to glue the pieces back together.
For the conservation of the Pietre Dure portions two options were considered.  In Florence, the missing elements would have been replaced with new cut stone.  The Pietre Dure objects are decorative and require a high level of finish.  Another Italian treatment option is to cast crushed stone and resin to recreate the missing inlays.  This second approach was chosen and the new Pietre Dure elements were created with tinted epoxy bulked with fumed silica cast into silicone rubber molds.  In some areas it was necessary to back of the Pietre Dure areas of loss with a layer of Japanese tissue coated with B72.  The epoxy elements were then cast directly into the loss.  Gamblin conservation colors were used to finish off the top of these fills and a layer of Acrysol WS24 was brushed on top to give a polished shine.
The micromosaic repairs were based on similar micromosaic designs.  Since the micromosaics were mass produced with only a small range of designs, similar images could be used as guidelines for decorative elements on the fills.  The areas of loss in the micromosaics were backed with acid free matt board topped with a layer of modostuc.  Gamblin conservation colors were used to inpaint the surface in two steps.  The first step painted the background colors and the second step painted the individual small tesserae.
This was an elegant and well executed treatment with results that were aesthetically pleasing and reversible.  Under close examination, the areas of filled loss are distinguishable from the original material.  This was a great talk and I hope to get a chance to work on micromosaics someday!