|AIC members from all specialty groups are invited to attend and participate in the event “A failure shared is not a failure: learning from our mistakes,” happening on Saturday, June 2nd, from 4:30 to 6:00 p.m. — click here to add it to your Sched. We will gather and share our cautionary tales, including treatment errors, mishaps, and accidents, with the idea of helping our colleagues not to repeat them.
Discussing mistakes is a hot topic that has already been embraced by others in our community. Two examples of events scheduled during the month of May are: “Mistakes were made,” a regular feature at the American Alliance of Museums conference, and the lecture “Conservation Confidential” hosted by our conservation colleagues across the pond in the Independent Paper Conservators’ Group.
Participants can speak for up to 5 minutes; if you prefer to remain anonymous, a reader will be happy to present your tale on your behalf. If you are unable to attend AIC’s Annual Meeting but would like to submit a tale to be read by one of our organizers or a colleague, please reach out.
Screens to project PowerPoint slides containing your images/video will be available (16:9 format), and a Dropbox folder will be made available for submissions. Please also bring your presentation on a USB Drive (highly encouraged). Time permitting, audience members inspired by their colleagues will be welcome to present. If appropriate (and acceptable to the speaker), the floor will be opened for questions and discussion following presentations. Extra points for suggesting safeguards and solutions!
Please note that this is a forum for sharing personal mistakes and solutions only. Participants are requested not to name other persons, organizations, work places, and avoid politics—institutional, national, and global!
The event will include a cash bar, so come, relax, unwind, share, laugh, groan, and learn. We plan to publish the event for those who wish to be included.
If you are interested in participating or have questions about the event, please contact Tony Sigel at email@example.com or by calling 617-767-1900 (cell), or Rebecca Gridley at firstname.lastname@example.org by May 10th.
Please include 2-3 quick sentences introducing your topic and indicate whether you plan to use a PowerPoint with images and/or video.
See you in Houston!
Claire’s talk highlights a topic that I’m glad we conservators are beginning to talk about more openly – treatments that didn’t necessarily work. This subject also fit in nicely with the overall conference theme of treatment and innovation. Although some of her treatment steps did not bring about the desired results, Claire was successful in safely and aesthetically preparing the ceramic so that it can be exhibited at the Freer Gallery of Art.
The earthenware dish features a reddish-buff ceramic body, off-white slip, and transparent glaze, with minimal brownish-black and red inscription decorations. The ceramic was previously broken into about 40 pieces and restored, with multiple campaigns of adhesive and overpaint. The museum has records of one treatment in 1964, and while removing old repairs, Claire found evidence of at least two previous restorations which likely occurred before the object was acquired in 1954. The major condition issue was various types to staining, including general yellow and gray stains. Additional disfiguring stain lines were present a few millimeters in from the edges of the sherds, including some areas with two or three separate rows of parallel staining.
Claire carried out analysis in an effort to determine the cause of the staining. Using SEM-EDS, among other tools, she determined that the staining contained little iron and was primarily organic in nature, meaning it is likely not from burial but from the various restoration campaigns. Adhesive identification was inconclusive, likely because multiple types are present; however, Claire noted the presence of hide glue, some type of acetone-soluble adhesive, and possibly shellac. During testing, the staining did not appear to be soluble in a range of solvents, likely because of crosslinking. Soluble salts were also identified with a microchemical test for chlorides, although no salt efflorescence was visible. An iron-containing accretion on the back within the footring was likely from burial and was mechanically reduced to avoid transfer to other areas of the ceramic during stain reduction treatment.
Claire proceeded with stain reduction tests, following Bruno Pouliot, Lauren Fair, and Richard Wolbers’ method of three rounds of poulticing using a chelator, bleach, and a final rinse.* She ultimately chose sodium citrate (2% at pH 8) as the chelator because it was mild yet effective, and she used carbamide peroxide (20% at pH 8) as the bleach. For both of these steps, she used agarose gel (2%) as the poultice material, favoring its ability for controlled, localized application. The gel poultices were only applied to stained areas on the front surface of the ceramic.
Agarose gel is made by mixing the powder with water, heating to a low temperature, pouring the mixture out to cast, and then cutting into blocks when cool. The gel blocks can then be soaked in solution; for instance, Claire soaked blocks in the chelator for one hour before applying to the ceramic. Plastic wrap was used to cover the gel blocks while on the ceramic to reduce evaporation. For the final rinse, the sherds were soaked in baths of deionized water, which served to clear the chelator and bleach as well as desalinate the ceramic.
To complete the treatment, the sherds were joined using Paraloid B-72, which was also bulked with microballoons and fumed silica to fill gaps and losses. These areas were inpainted as the dish will be displayed in an art museum, as opposed to an archaeological context, and the curator preferred to have the losses integrated.
Although the staining was somewhat lightened, its appearance was not sufficiently reduced by the poulticing steps. Claire carried out many poulticing trials, but the staining proved tenacious and she did not want to take the treatment so far as to risk causing damage to the object. Although improvements were made, the curator still did not find the dish to be in exhibitable condition, since the staining lines were still visible and particularly distracting against the overall stark, white appearance of the ceramic. At this point, Claire decided to try painting out the stains, over a barrier layer of B-72. Although she did not like the idea of painting over the original ceramic surface, this seemed to be the only reasonable option for preparing the object to be exhibited and accessible to public. Painting light over dark and matching the surrounding off-white glazed slip must have been a challenging task. But in the end, conservators and curators were both pleased with the results!
* For more information, I recommend: Bruno Pouliot, Lauren Fair, and Richard Wolbers. “Re-thinking the Approach: Techniques Explored at Winterthur for the Stain Reduction of Ceramics,” 2013 in Recent Advances in Glass, Stained-Glass, and Ceramics Conservation, pre-prints of the ICOM-CC Glass and Ceramics Working Group Interim Meeting and the Forum of the International Scientific Committee for the Conservation of Stained Glass, Amsterdam. pg. 211–223.
Author Sara Wohler discussed the fascinating history of Alexander Calder’s airplane model, Mexico #3, the last work he completed before his death, and then presented the conservation treatment of the model. Author Ralph Weigandt then discussed the technical analysis of the paint film on the airplane. This presentation served as a fun continuation of the painted airplane theme, following Lauren Horelick’s May 30th talk “When an Airplane Acts like a Painting: Applying Established Conservation Methodologies to Ephemeral Aircraft Materials.”
Wohler described the beginning of Alexander Calder’s airplane-making career: In 1972, New York advertiser George Gordon approached Calder with the idea of painting an full-scale airplane. Calder loved the idea, as it would combined his experience in kinetic art and his background in engineering. Gordon paired Calder with Braniff International Airways, and Calder created the designs for two airplanes: Flying Colors of South America and Flying Colors of the United States. These were both tremendous public successes.
^Braniff International Airways employee ceremony, 1975, with Flying Colors of the United States.
The author then described the process in which Calder painted the planes: He began by experimenting with designs on several 1/25-scale Westway Aircraft Models. The chosen design from the model was then scaled up using graph paper that was attached to the full-size airplane. Calder and his team then used pounce wheels to poke holes through the design on the graph paper, and black spray paint was applied through the pounce holes. The graph paper was removed, and the paint colors were spray applied by a Braniff team. Calder supervised the entire process, and hand-painted the engine necelles during the spray process.
Then the author described the artistic process for the model Mexico #3. In 1976, Braniff commissioned a third plane from Calder, this one to celebrate the great relationship between the U.S. and Mexico. The author provided amazing historic film footage of Calder painting the Mexico #3 model plane. She noted that the plane itself was made of fiberglass, and Calder created his design using gouache. On November 11, 1976, Calder completed and signed the work, and tragically, passed away later that evening. Although the design was completed, Mexico #3 was not transferred to an airplane, as Calder was no longer alive to approve of the final result.
^Calder painting the Mexico #3 model.
The model airplane was brought to Kuneij Berry Associates, Chicago, for conservation treatment. Through examination, the author found that the fiberglass model airplane had two priming layers, blue and grey, and a final, even, white coating. Calder painted onto the proprietary white surface using gouache, possibly that he made himself. While the airplane was quite dirty and structurally had sustained a few losses, the treatment was relatively straightforward.
The plane was in poor aesthetic condition; it had previously been displayed in a planter with dirt and plants around it, exposing it to both dirt and moisture. Fortunately, the gouache paint layer was generally in good condition and intact, aside from a few abrasions. The synthetic varnish layer, which had protected the gouache layer, was covered in surface dirt and grime. The plane was first surface cleaned with deionized water and PVOH sponges, but a lot of the dirt remained embedded in the varnish. The synthetic varnish was removed with aromatic solvents. Care was taken to only thin the varnish on top of the gouache paints, as the paints were sensitive to aromatic solvents.
^Detail of the varnish removal, cleaned (left) and with remaining varnish (right).
Structurally, the plane had suffered a few chips to its wings and there were a few areas of flaking paint. The flaking paint was consolidated with Paraloid B72. To recreate the tips of the wings that had been chipped away, molds were made of Elastosil M4600 A/B and cast using Milliputti. The cast pieces were sanded and adhered to the wings using Paraloid B72.
Shallow losses in the white priming layer were filled and inpainted simultaneously with Golden MSA colors. Losses in the gouache colors were then inpainted with QoR watercolors. The model was then sprayed with a few, light, protective layers of RegalRez 1094. After the successful treatment, it was recommended that the painting be displayed in a new, more environmentally stable location.
^Sara Wohler inpainting Mexico #3.
The technical analysis of Calder’s gouache paint was carried out by Ralph Weigandt, who is currently the primary researcher on the collaborative National Science Foundation (NSF-SCIART) grant with the University of Rochester’s Integrated Nanotechnology Center to advance the scientific understanding and preservation of daguerreotypes. The authors carried out technical analysis of the gouache paint in order to better understand Calder’s materials and techniques, potentially inform the conservation treatment, and to pioneer the use of Focus Ion Beam (FIB) milling for SEM-EDX analysis and PLM examination on paint films. Through Transmission Electron Microscopy, SEM-FIB allows for the elemental analysis of paint layers at the nanometer scale!
Weigandt explained in depth about the sample preparation process, the Focus Ion Beam milling of the larger sample into the much smaller (~12 um x 0.5 um) cross-section, the comparison between traditional SEM-EDX spectroscopic elemental analysis and mapping vs. the Transmission Electron Microscopy and associated SEM-EDX elemental analysis and mapping capabilities. In essence, the FIB milling and TEM allows for highly precise, high resolution elemental analysis and mapping, allowing scientists and conservators to see the inorganic composition of individual pigment particles. A poster from University of Rochester graduate student So Youn Kim outlines the project with excellent photographs and illustrations.
In the end, the elemental analysis did not contribute greatly to the decision-making process of the treatment, but did provide excellent information about Calder’s painting techniques and materials for Mexico #3, which can inform a discussion about his art-making process for this piece and his art in general. It is clear that this Focus Ion Beam technique coupled with Transmission Electron Microscopy and SEM-EDX elemental analysis is an exciting analytical technique that will be extremely useful in the precise identification of inorganic pigments, fillers, etc., in paint films. Furthermore, it is great to see yet another example of private conservators working with scientific departments at universities (or elsewhere) to investigate materials of cultural heritage objects!
This is a joint paper by two objects conservators at the Metropolitan Museum of Art, Carolyn Riccardelli and Wendy Walker. Along with many others at this conference, the topic of this paper concerns treatment and installation considerations of Renaissance-period glazed terracotta from the della Robbia workshop. This paper discusses two masterpieces by Andrea della Robbia (1435-1523), both pretty dramatic in their scope of treatment.
The first, a lunette of Saint Michael the Archangel, starts with a tragedy. In 2008, it came crashing to the floor from over a doorway in the 15th Century galleries where it had hung on display at the Met since 1996. If you search online, you can find articles about that event, but I will not link to any of them here. What I will link to, however, is the press release from April of last year, announcing that the lunette is restored and back on view.
Riccardelli presents the treatment that took place over eight years, a massive undertaking mainly overseen by Walker. She describes how it offered the conservators a rare peak into the working methods of della Robbia. For example, they could see in a more intimate way exactly how the clay used to mold the lunette was wedged (not very well at all), which tells us that the makers must have understood their clay so well to know this step wasn’t necessary. They also found evidence of tool marks and fingermarks – yes, even fingerprints! – from pressing the clay into the molds. The paper outlines the treatment of this work, which includes the use of the “Tulio blend” (3:1 B-72/B-48N in acetone with 6% ethanol) as the main adhesive, and a mount that incorporates brass clips to hold the panels to an aluminum backing panel. We are all left with beautiful after-treatment images of the lunette and a happy ending to the story.
The second della Robbia piece presented, a massive tondo of Prudence, starts with an exhibition announcement at the Museum of Fine Arts, Boston, Della Robbia: Sculpting with Color in Renaissance Florence. Along with pieces from Italy never seen in the United States before, as well as loans from the Brooklyn Museum and the Los Angeles County Museum of Art, the Met’s Prudence was featured.
Riccardelli presents the conservation efforts to get Prudence ready for loan and exhibition, having one year to do it. The piece consists of 16 molded and modeled sections – a central tondo surrounded by a colorful garland – and nearly every piece had old restorations that needed to be addressed. This included an unstable mount. Their paper outlines the treatment steps taken, including cleaning and restoration removal (steam, solvent, mechanical), and a well-engineered mounting system that employs carbon fiber clips and straps, and a honeycomb aluminum backing panel. (More details about the use of carbon fiber clips in this treatment are presented in Riccardelli’s other paper during this conference, “Carbon Fiber Fabric and its Potential for Use in Objects Conservation.”)
It was during the cleaning phases that the conservators again made an exciting discovery, uncovering original markings and finger impressions that clearly indicate the proper order of the garland border pieces. More than this, the pre-treatment arrangement of the garland was incorrect! Their paper shows the dramatic shift from the previous arrangement to the corrected one, totally altering the feel of the piece and giving one the satisfaction of being able to return something home to its rightful place.
In the abstract for their paper, Ariel O’Connor, Smithsonian American Art Museum (SAAM) objects conservator, and Dan Finn, SAAM media conservator, write that this presentation “aims to present a case study that is exemplary of the wide range of expertise that time-based media conservation can require, and the collaborative approach that it necessitates.” Their talk certainly demonstrates this, as it presents a myriad of challenges, from documentation tasks and working with living artists, to what to do when a massive cable failure occurs just minutes before the museum director is coming to see the work in action.
The paper discusses the kinetic sculpture titled “the willful marionette,” by Brooklyn-based artists Lilla LoCurto and Bill Outcault, and the piece incorporates sculpture (a 3-D printed, blue poly(lactic acid) biodegradable plastic marionette with strings made of fishing line), software (Puppet Master), and electronics. The custom software is designed to interact with its audience, responding in real time to recognizable human gestures with gestures of its own. Meet the artists and get a glimpse of the marionette, affectionately named Little Bill, in this short video.
O’Connor and Finn outline the documentation process they employ at SAAM, making us all realize how incredibly detail-oriented the documentation of time-based media works really needs to be. This includes a testing and acceptance report, an identity report, various iteration reports, documentation photographs, artist interviews, copious notes, and organization and storage of all files, such as the STL files that can be used to reprint the sculpture in the future, if need be.
The authors candidly recount stories about working with this exciting and challenging piece and getting it ready for the museum director to review. For instance, an issue with Little Bill not blinking properly was fixed by the good old “CTRL-ALT-DEL” method. But when the 80-lb. line that mainly held up the sculpture spontaneously snapped, they had to be resourceful and quick-on-their feet, looking to the facilities crew for the right tools needed to remedy the situation.
Future challenges for this work are similar to many time-based media works, including what will happen to the proprietary software that Little Bill is operated on, as well as storage considerations for the plastic sculpture itself.
This year ECPN rolled out a new program during a pre-meeting session that allowed poster presenters another venue to share their projects and research. I was very excited for this session because I have felt overwhelmed by the number of posters and limited free time to view them. A similar sentiment was later echoed at the AIC Business Meeting. I hope that ECPN (or AIC generally) considers organizing a similar session next meeting and I would encourage anyone looking for more engagement with poster authors to attend.
This session was in no way comprehensive of all the poster submissions. ECPN members received a notification about the session about a year before the meeting. However, ECPN contacted all poster authors once they were accepted to the general AIC poster session. The email solicitation encouraged “emerging conservation professionals” and “topics relevant to ECPs (not necessarily authored by ECPs)” according to Rebecca Gridley, ECPN Vice Chair and one of the organizers of the session. There were 14 presenters total this year, which were chosen from email responses of poster authors indicating an interest in participating. The final selection was chosen to offer a range of talks across specialties and include speakers spanning the ECPN demographic, according to Gridley. Unfortunately not every author interested was able to be included due to time restraints of the session, but ECPN is considering how this could be improved in the future.
This year’s inaugural Lightning Round did seem to have mostly young presenters including pre-program, graduate students, and recent graduates. It does seem that ECPN is trying to be more inclusive and the demographic of “ECP” is only loosely defined. Certainly the audience this year was more diverse than the presenters and included AIC Fellows and other more established professionals in the field. At the same time, the environment of the Lightning Round felt very safe and welcoming. We were seated at round tables, which was more casual than auditorium seating. This was a great opportunity for first-time presenters to get their feet wet. One of the speakers was a first-time attendee and presented on her first conservation treatment ever as a pre-program. This session promoted information sharing and dialogue—activities that I personally feel will only help strengthen our field.
Alex Nichols reflecting on the benefit of the Lightning Round said, “I was approached by several conservators and researchers in specialties other than my own [modern and contemporary objects] who said that they were introduced to my research through the lightning round presentations.” In comparison to the last time Nichols presented a poster (at the 43rd Annual Meeting in Miami), she had more people ask about her research, which she attributes to the exposure from the ECPN Lightning Round.
The 14 poster topics were divided into two rounds, which allowed for a necessary intermission/bathroom break. The rounds were moderated by Michelle Sullivan, ECPN Chair, and Rebecca Gridley, ECPN Vice Chair.
In the spirit of the “Lightning Round” each presenter was given two minutes and three content slides to summarize their poster at the podium. This seemed like a daunting task and like I might not receive much more information than the title of the poster. I was really impressed with how clear and concise all the speakers were (I think the tambourine—symbolizing time’s up—only had to be used once). I learned a lot from the brief presentations and there was even time for one or two questions for every speaker. Having the visual component of the slides I felt took this beyond what a written abstract can offer. The Q & A was also very lively and I think emphasized how valued the poster presentations are to the conservation community.
I found this Lightning Round useful not only for the direct information, but also in helping me be more efficient with my time in the exhibition hall with the posters. Each PowerPoint included the poster number for easy reference to the location in the exhibit hall. Feeling similarly, Claire Curran, Assistant Objects Conservator at the ICA, also in attendance, and reacted, “definitely visiting this one—sounds really cool” in response to a treatment of a Hopi Katsina doll. The room was filled and there seemed to be a strong positive response to the session.
To keep things light and encourage additional networking during the ECPN Happy Hour (which immediately followed the Lightning Round) a fun fact about each presenter was announced in addition to his/her professional bio. For example, Sarah Giffin was introduced as the “meat whisperer” because of her delicious slow cooking brisket recipe.
I am embarrassed to say that I did not know that the posters are published on the AIC website after each Annual Meeting. You can access them here.
To help your exploration of the .pdf files online, here are some of the highlights each presenter chose to emphasize during the ECPN Lightning Round.
#30 Conservation in Miniature: The merger of museum object and historic interior in the treatment of a Victorian era dollhouse
- Applied in situ treatment methodology used for full-scale interiors to miniature interior of Horniman dollhouse
- Mist consolidation with nebulizer using Klucel G in acetone (tests in water solubilized tannins in wooden walls creating issues with tidelines)
- Condensation in the small tube was a challenge and had to tap out liquid droplets at times
#60 Conservation and Art Historical Data goes Digital at the Art Institute of Chicago
- Interactive website for conservation treatment of a collection of Alfred Stieglitz photographs and some contemporaries
- Used WordPress platform because easy interface and allowed for frequent updates to content
- Provides links to art historical information as well conservation/ technical information and research
#44 Applying Fills to Losses in a Flexible Polyurethane Foam Chair at the Museum of Modern Art
- Research and analysis to confirm type of foam composition of the chair
- Bulked methylcellulose and grated polyurethane foam for consolidation and filling of losses; liquid nitrogen helped harden foam enough to easily grate and shape
- Inpranil DLV/1 is a traditionally favored consolidant for polyurethane foam but has been challenging to acquire
#92 Chemical Cleaning and Intervention Criteria in a Brass Dial Clock from the XIX Century
João Henrique Ribeiro Barbosa
- Clock face (only surviving element of the clock) composed of three different metals joined together with rivets
- Previous cleaning by polishing left white residues and new corrosion products developed underneath
- Ammonium citrate solution addressed polish residues with “DTCNa” or sodium diethyldithiocarbamate solution addressed corrosion products
#24 History, Treatment, and Preparation for Digitization of 14th-century Estate Rolls
- Surface cleaning, humidification, repair with Japanese tissue
- Rehousing to handle during treatment, digitization, and future research
#42 Treatment and Reconstruction of a Badly Damaged Hopi Katsina Doll Made of Gourd
- Gourds painted in acrylic
- Treatment included surface cleaning, consolidating cracks, introducing new internal armature to help with reassembly and stabilization
- Used silicone self-adhering bands to secure while mends were setting
- Armature was set in place before doll head was reattached; tensioned wire extending to wings before head was placed back on
#10 Towards Nondestructive Characterization of Black Drawing Media
- Redon drawings were used for case study
- Redon working period overlapped with commercial materials available in 20th century
- Macro XRF scanning used to map elements combined with micro Raman spectroscopy
- Characterization relied on peaks in fingerprint region and peaks indicative of known additives to distinguish between different carbon-based media
- 785nm laser for Raman because of heavy use of fixatives on the drawings
#27 (I Can’t Get No) Documenation: Preservation reporting in the Archives
- Established a template “Preservation Report” for standardized documentation and condition reporting
- Focus on up-to-date condition and documentation of current status of projects and personnel involved; address realities of institution with changing/temporary staff and disruptions project workflow
- Format based on feedback from other institutions and existing condition reports in the archive
#80 Bedbugs: A pesky problem
- Addressing infestation of a Lakota teepee in private hands installed behind owner’s bed
- Freezing unsuccessful likely not able to achieve low enough temperatures throughout
- “Solarization” using hatchback car appeared to work (i.e. no live bugs remained)
- For domestic infestation chemical treatment often necessary for bed bugs; they are night feeders and hide during the day
#32 Treatment of a Shattered Bark Basket from Australia
Marci Jefcoat Burton
- Basket likely eucalyptus bark sealed with natural resin
- Consolidated with B-72; bridged with tissue and blend of Lascaux adhesives
- Removable internal support for storage constructed of backer rod (trapezoidal shaped Ethafoam strips) shaped to the contour of the basket and padded with Volara
#84 Lifting the Microfiber Veil: Utilizing Evolon fabric at the Mauritshuis to remove aged varnish from Hendrick Heerschop’s A Visit to the Doctor
- Evolon is 70:30 polyester: polyamide spun-bond fabric
- Evolon originally developed as anti-bug fabric
- Used to lift and remove aged varnish; gentle and appropriate for surfaces with extensive lead soap networks
- Polyamide fibers are hydrophilic and contribute to aqueous cleaning
#22 Captain America Encounters Klucel M
Michiko Adachi and Cathie Magee
- Captain America pages had been stapled together in case binding
- Mending utilized solvent reactivated tissue to avoid solubility issues and tidelines from acidic migration of newsprint substrate
- Klucel M used as adhesive because of strength and transparency
- Klucel M artificially aged by Library of Congress and seems to have similar properties/behavior to Klucel G
#67 Initial Treatment Techniques for Japanese Lacquer-based Metallic Thread and Cut Paper Applique
Elinor Dei Tos Pironti
- Solubility testing was used to characterize original adhesive for metallic paper threads on a Japanese garment
- Urushi was used to consolidate metallic threads
#31 Under Close Observation: A pilot study monitoring change in objects’ conditions
- Summarizing current research and findings of the Managing Collections Environment Initiative at the Getty
- Comparing different methods of monitoring conditions of objects including photographic documentation (DSLR, point and shoot camera, iPhone), caliper measurements to monitor cracks, acoustic emissions
- 14 objects representative of materials found in institutional collections used for case study; exposed to humidity cycling
Remy Dreyfuss-Deseigne described research related to mending methods for transparent materials using nanocellulose films. His research has been carried out with several institutional partners, at the National Library of France (BnF, Paris, France), Research Center for Conservation (CRC, Paris, France), French Museum of Cinema, and during his 2015-2016 NEA fellowship in paper conservation at the Conservation Center for Art & Historic Artifacts (CCAHA, Philadelphia, PA).
Remy opened with some images of difficult structural problems: torn gelatin windows, animation cells, and architectural drawings on tracing paper. He then introduced nanocellulose, explaining how it is made, what its properties are, and its potential for use in conservation.
His work focuses on one kind of nanocellulose, microfibrillated cellulose (abbreviated MFC). Nanocellulose materials are produced for a variety of uses in electronics and biotech, and are being researched and manufactured by several universities including in Grenoble, France and at the University of Maine.
Nanocellulose is produced by mechanically shearing wood to rip apart the fibers until they are nano in scale. Cotton, spruce and birch can all be used as sources for nanocellulose. The amorphous parts of the remaining cellulose structure are treated with acid in order to dissolve them, leaving highly crystalline fibrils. There is a lot of ongoing research into the production of nanocellulose in the nanotechnology, renewable materials, and sustainable engineering fields.
For conservation applications, Remy compared the properties of nanocellulose films to lightweight Japanese papers like gampi and kozo used to mend tears on translucent artworks. Nanocellulose is supplied as a gel that can be cast out by pouring into a petri dish and evaporating out the water, creating films that vary proportionally in thickness related to concentration. Remy’s research investigates its properties in combination with different adhesives, and its response to artificial aging tests (light, temperature and humidity) as well as mechanical strength tests.
He found that the nanocellulose films were thinner than papers but quite strong (nearly as strong as Gampi), and mostly behaved like cellulose, a good thing for their use as a paper conservation material. Most importantly, mends made with the thin films are practically invisible in regular and transmitted light. These mends were demonstrated on translucent slides with tears from the collection of the French Museum of Cinema (impressive work!). Ongoing testing will include further analysis of the material, e.g. pH and mechanical strength measurements and fungal resistance tests.
While this was the first time I had heard about nanocellulose it has many potential uses, and not just for mending translucent materials. As a biomaterial derived from renewable forestry resources, nanocellulose has gotten a lot of attention over the past five years for its potential in industrial applications. Given its high ratio of strength to weight it has great potential for use in fill materials of all types, and has already found applications in industrial 3D printing as a substitute for carbon fibers in composites. Since it is compatible with many adhesives, it may find wide-ranging applications in conservation. I am looking forward to hearing more about Remy’s ongoing research and thank him for the excellent introduction to an interesting material. You can learn more about Remy’s work at his website.
Jan Cutajar is Research Assistant at the University College of London, and Hana Bristow is Assistant Conservator at the National Museum of the Royal Navy, Portsmouth. They jointly presented on their experiences making acrylic resin fills with Paraloid B-72, an acrylic co-polymer, for use with glass repair. They based their work on techniques previously established by Steve Koob from the Corning Museum of Glass and recently updated at the CCI Symposium in 2011 (See here for the last update: https://www.cci-icc.gc.ca/discovercci-decouvriricc/PDFs/Paper%2035%20-%20Koob%20et%20al.%20-%20English.pdf).
Cutajar and Bristow treated two archaeological glass vessels: one Sassanian glass from UCL, and one beaker from Exeter, as case studies. They had common goals of needing reconstruction, stabilization, and the ability to be studied. They also had similar physical characteristics of degraded but stable glass with relatively good contact between the extant shards, thin walls (as thin as 0.2 mm), and substantive loss around of 35%.
In looking for a fill system, they wanted a material that could reinforce weak areas, aid in practical assembly, and be as minimally interventive as possible. Since working with epoxy would require considerable manipulations with the artifact for both direct and indirect casting methods, this was not chosen. Instead, acrylic resin fills were explored because they are lightweight, strong, flexible, thin, detachable for future retreatment, simple to produce and insert, and can be manipulated for color and opacity matching.
Koob’s technique is based on 30% w/v Paraloid B-72, an acrylic co-polymer, in acetone, with ethanol added to slow the evaporation rate, thereby reducing the potential for bubble formation. For coloring, ground pigment can be added to the ethanol before adding it to the resin mixture. The pigmented ethanol should be first decanted to prevent larger pigment particles from being added. The solution is cast and stored in a partially sealed environment for slow evaporation. Bristow felt that B-72 alone was too flexible, so she explored resin mixtures and tested varied proportions using B-72, B-48N or B-44 either straight or mixed in 2:1 ratios but always 30% in acetone. She also tested these opacifiers: fumed silica, marble dust, titanium dioxide and whiting. She cast the test resin mixtures in boxes of the same size, also holding the volume and concentration of the solution and the volume of added ethanol constant. The tests were evaluated after 4-5 days of curing for hardness, plasticity, and appearance. She found that a 2: 1 solution of B-72: B-48N produces a strong film without brittleness. This film was stronger than the B-72 film and not brittle like the B-48N alone or B-44 films.
For the opacifiers, Bristow found that fumed silica worked well for adding translucency, and marble for opacity, but whiting and titanium dioxide produced speckled results and were difficult to homogenize with the mixture. She also notes that dry artist pigments are good for tinting but shouldn’t be relied on for opacity as well, because they easily over saturate the mixture, resulting in a cracked and weakened cast. She recommends a maximum of 1.5 micro-spatula scoops per 30 mL resin mix.
Cutajar and Bristow offer some practical notes and tips:
- Achieving desired film thickness can require some trial and error. Expect about 70% volume shrinkage.
- Trays should be non-absorbent and easily release the resin. Making or using solvent-resistant boxes lined with release papers or films works well.
- Enclose the poured resin trays in an acetone rich environment to slow the rate of evaporation. This will help prevent bubble formation.
- Films should set for at least 4-5 days before removing, otherwise the films are too flimsy for these applications.
- Films are best to manipulate directly after demolding. Things that can be done are:
- Cutting – determine the size by taking a tracing of the loss area
- Shape can be adjusted using heat; about 20 seconds under a hair dryer works well. Once warm, hold the cast in the desired position until it cools enough to hold the new shape. This can be done through repeated heating and cooling cycles until desired shape is achieved.
- Adapt a cast by creating a lip at the edges where joins are very thin. This creates a slight overlap with the adjacent glass. The lip can be created with a heated spatula away from the glass.
- Bonding can be activated with acetone, but Cutajar and Bristow suggest using more adhesive (Paraloid B-72) to make the join since acetone can compromise a good fit.
- The film can be cut into tabs and used as reinforcements across joins. Cut the tabs into shape, lay them across the join, and activate with solvent. The tabs are virtually invisible.
- The film can be used to make recessed fills for backing thin, curved glass, providing local stabilization and weight redistribution.
- Backing films are easier to apply when they are freshly removed from the solvent atmosphere and retain a slight tack.
Paula Artal-Isbrand, Objects Conservator at the Worcester Art Museum, presented the various ways in which she uses paper in her objects treatments. She shared some background on paper types. Asian papers typically come from the paper mulberry tree and produce long fibers (kozo) and strong paper or from the gampi tree, producing shorter fibers to make crisp and translucent papers. Mitsumata shrubs are a third source, but not part of this presentation. Western papers are more often made from cotton, linen, flax, or hemp. Paper in conservation is strong, inert, compatible with conservation materials, has excellent long-term stability, and does not pose health risks. It can also be manipulated to mimic a wide range of materials through inpainting and coating. By choosing the right coating materials, the translucency and texture can be adjusted to fit the application. These papers can also be inpainted with standard inpainting materials to match color and texture.
Artal-Isbrand outlined two ways for thinking about how to use paper. First, it can be used as a restoration material. Artal-Isbrand offered several examples of how she’s used paper in this way. For example, she used acid-free matboard cut into shape for a loss repair in a fan. For archaeological glass, she toned paper kozo paper with watercolors (not with acrylics since they would create too much opacity) and impregnated the paper with Paraloid B-72, acrylic co-polymer. The toned and resin soaked fill was a perfect match for the glass and was attached with Paraloid B-72. She has made paper fills to reconstruct chain mail, for joining heavy elements of an iron helmet, for reinforcing failing solder joins for bronze armor, and for backing a Roman lead curse tablet that needed to be unrolled. These repairs were carried out using a combination of kozo paper with Paraloid B-72, and are a testament to the paper’s strength. Artal-Isbrand also described that paper can be an interlayer between an artifact and fill material to ensure reversibility and how cellulose powder can be a bulking additive for fills, and if toasted, can also impart pigment to fills.
Second, paper can also be used as a tool. It can work well as a facing for an intermediate phase of treatment. It can also serve as a barrier layer. For example, thin papers are a great barrier film for gels. Here, Artal-Isbrand mentioned that thin gampi paper can be good for this. The paper is placed between the surface and the gel, allowing for easier clean up in gel removal. Paper can be a poultice material. Artal-Isbrand uses Whatman cellulose powder, which will cling well and hold the poultice solvent. For these same reasons, shredded filter paper soaked and blended in water can be used to create a mold of another artifact. The mold should be sealed with resin (for example, Paraloid B-72) to keep it from getting damaged by water applications. If using the mold for creating a plaster fill, this step is critical.
During the question / answer period, there was a brief discussion on how shredded paper serves well for poulticing, and is better than cellulose powder or other very fine materials, because those become difficult to remove and can leave a hazy residue. So, it is important to distinguish between powder and pulp or shredded and/or ground paper. An interleaving layer can be helpful if powder is used. Also during the discussion, another example was mentioned that paper can be rolled into “worms,” impregnated with Paraloid B-72, and inserted it into losses to provide filling that is more easily removed than putties or other fillers.
In this talk, Megan Randall, Objects Fellow at the Museum of Modern Art, tells the unique treatment history of Bruce Conner’s Child from 1976 – 2016. Bruce Conner was an artist who worked across media, from collage and sculpture to painting and drawing. Created in 1959, his sculpture Child is a corpse-like figure made of casting wax and shaped by hand. He sits in a high chair and is bandaged with stocking fabric and a belt around his waist, with additional wax painted on the surface. Child was made in response to the execution of Caryl Chessman, which Conner believed to be a social injustice.
Megan structured her discussion to be a timeline of Child’s complex exhibition and treatment history and described the numerous events that resulted in the figure’s condition when she first arrived at MoMA as a fellow in 2015. The sculpture was first exhibited in 1960 and received great attention from the public. It continued to gain exposure at galleries, in Conner’s one-man show, and even in public protests against police brutality and in 1970, was acquired by MoMA. The work was treated in 1976 in which the cheeks and head needed to be stabilized and an arm mended. Then, later that year, it was exhibited at SFMOMA, where Conner was disappointed to see its state significantly worsened. At this point, there had been no direct contact between MoMA and Conner, but he referenced the Geoffrey Clements photograph of how Child was originally positioned. It was clear that the shape of the figure had been badly deformed. The full figure had slumped forward, the mouth was now closed rather than open, and the legs had lowered and were in complete contact with the chair. However, it continued to tour at Hirschhorn Museum in 1988 and then at the Whitney in 1996, where Conner saw it once more and horrified, requested that it immediately be taken off view.
After several correspondences between MoMA and Conner, with the artist’s input on what needed to be adjusted, it was decided that a treatment of Child was necessary. Much of the issues with the positioning of the body was a result of the failing handmade hardware and joints and during an unfortunate turn of events during treatment, the body fell apart. Luckily all the original material was maintained, and the challenge was in terms of its assemblage. Sadly, Conner passed away in 2008.
In 2015, Megan Randall and Associate Objects Conservator at MoMA, Roger Griffith, started the journey to restore the exhausted Child. They began with documentation of the figure including imaging, photogrammetry to observe the three-dimensional positioning, and radiography to get a sense of the joining materials and the thickness of the wax. Child had been a victim of transport, handling, and failing of structural elements between its conception in 1960-2000.e treatment aimed to return the figure and vintage nylon stocking to their original orientation and stabilize the materials, while using images from the archive and Conner’s studio as reference.
Using a Go-Pro to document the process, the conservators carefully disassembled the figure, photographing each individual section and even had a carpenter create a replica of the high chair that Child sat on so that they could build up the figure away from the original nylon and wood. Loose sections were consolidated and the wax that had deformed was readjusted with heat and pressure. The next challenge was to create an armature that would help support the weight of the wax, as this was one of the original causes of the figure’s collapse. After months of testing, Megan and Roger decided to use polycaprolactone (PCL), an orthopedic thermoplastic polyester resin. It suited this project as it is a conformable, adjustable material that can withstand travel and is long lasting. Altraform was added into the armature and 3D Light Mesh was used to support weight from above as well. These materials were also Oddy tested and deemed safe for conservation practice.
After the figure was positioned back together, Megan and Roger had to tackle the vintage nylon stockings. Luckily, most could be repositioned safely, but three pieces needed replacements, for which Roger ordered online and surprisingly, toned with coffee and tea, to obtain the distressed appearance that gave Child its haunting effect. Finally, Child was back in its original orientation and ready to be shown at the Bruce Conner Retrospective at MoMA, and then subsequently, SFMOMA and the Reina Sofia.
After treatment photographs were taken to capture the armature inside each section and several techniques were used for recording its position. Photogrammetry was captured once again to compare future sets for monitoring any potential deformations or movements and radiography was done in order to monitor if the armature moved in the future as well as if the figure shifted in any way. A custom crate was created for safe travel to its next two immediate exhibition spaces and it just returned safely to MoMA, much to the happiness of the conservators. Ultimately, Bruce Conner’s Child has a complicated and extensive history, including it falling apart, but after countless hours of testing and treatment by conservators at MoMA, the figure was returned to its intended appearance and we as visitors had the pleasure of viewing its haunting and delicate beauty.