44th Annual Meeting – Research and Technical Studies, May 17, "Binders and pigments used in traditional Aboriginal bark paintings” by Narayan Khandekar

This was the last talk I saw at the meeting and was a perfect way to wrap things up, with a travelogue-slash-fascinating research project on the materials and techniques of Aboriginal paintings from the northern part of Australia. Narayan traveled to various art centers and museums to look at and sample pre-1960s paintings, talk to artists and gather local materials. He took about 200 samples from 50 paintings (including some from Harvard’s collection), the oldest from circa 1878. He also obtained materials from artists working today, some of whom took him around to gather materials from local sources, including the beaches of Bathurst Island (part of the Tiwi Islands off the coast of the Northern Territories – thanks Google Maps!). Back at Harvard, he and his colleagues (co authors were Katherine Eremin, Daniel P. Kirby & Georgina Rayner) gathered information on pigments, binders and other materials present that may indicate previous treatments. Narayan pointed out that only two samples of similar paintings had been analyzed and published before, such that this study presents entirely new information.

Australia map

Of particular interest was the investigation into possible binders. Oral histories and documentary evidence recorded various possible binders, including turtle eggs and orchid mucilage, but it was generally thought that paintings made before the arrival of missionaries in the 1920s didn’t have binders at all (a similar question has been on my mind regarding the paintings made in the Sepik River region of Papua New Guinea). Binders were present in 77% of the samples analyzed. No proteins, waxes, fats or blood were detected. The analysis of the oldest paintings did reveal the presence of orchid juice, confirming that binders were in use that early. The techniques of using orchid mucilage could vary; the sticky juice could be mixed with the pigment, or laid down first before applying the pigments mixed in water.
As expected the pigments were largely ochres, and Narayan noted that the trace elements present in the samples provide a fingerprint that can in theory be used to begin to trace the occurrence of different ochres in different areas, but that more study and sampling is necessary to pursue this.

Colorful ochres on the beach

Other interesting findings included the use of dry cell batteries as a source for black manganese and zinc pigments on paintings from Groote Eylandt (yes a very great big island off the east coast of the Northern Territories); this area also shows the use of natural manganese-rich ores and charcoal for black pigments. A curious silver oil-resin paint on two paintings from the 1920s turned out to correlate with the roof repainting of a nearby lighthouse at the same time. The presence of DMP (dimethyl phthalate) in some paintings prior to 1957 resulted from the liberal use of insect repellent (FYI this is the main ingredient in Avon’s Skin-so-Soft; it fell out of use when DEET was invented). The presence of nitrocellulose on Groote Eylandt paintings was connected to records from the 1948 expedition suggesting that they had been consolidated with Duco.
As always, research continues, and Narayan mentioned that they would be looking further into the use of gums and of bloodwood, though I didn’t get down any details on that (I hadn’t actually planned to blog the talk, so apologies for any lacunae!). Also, I’m pretty sure there was a crocodile sighting mentioned, but that too didn’t make it into my notes, so here’s one of my favorites for good measure…

44th Annual Meeting & 42nd Annual Conference—General Session, 15 May 2016: "Visions of Disaster: Bringing the Blur into Focus," by Polly Christie and Sarah MacKinnon

Polly Christie and Sarah MacKinnon took us through the history of the 2014 Glasgow School of Art fire, beginning with how the building’s construction directly affected the scope of the disaster, taking us through the extent of the damage, and detailing the ongoing rescue process. Each component of this complex recovery project intersects with the others, demonstrating the interconnected nature of cultural heritage properties and the collections residing within.
Designed by Charles Rennie Mackintosh and built in phases, the Glasgow School of Art building is widely considered Mackintosh’s masterpiece, and is an early example of both total architecture and industrial design. The first phase, completed in 1899, saw the completion of the east wing, while the second phase, modified from the original plan, included the west wing and additions to the east wing, and showcases Mackintosh’s work at the height of his powers. The library tower, located in the west wing, borrows elements from Japanese architecture and was built to best accommodate the needs of the school. In addition, Mackintosh’s work includes an early air conditioning system of branched ventilation ducts running in straight lines through the entirety of the building.
These ventilation ducts, while certainly appreciated by the building’s occupants, were critically involved in the 2014 disaster. The blaze began in a basement studio and spread quickly throughout the building via the ducts, reaching the library tower and raging through the collections stored both in the stacks and in storage above the main library space. These collections were irreplaceable, including school archives, art created by alumni, historic furniture, and 11,000 special collections volumes.
The fire required 11 teams of firefighters and 24 hours to fight. Once the danger had passed, the mass of destroyed building and collections in the library tower was “excavated” or sorted through in one-meter-square areas, leading to the salvage of 81 volumes as well as important information about the underlying structure that would be used in the reconstruction effort. Triage systems and decision trees were established for sorting through the wreckage and recovering collections items.
A few collections merited particular mention in light of the recovery efforts. A large textile collection held in storage survived, but the packaging was destroyed; this was not covered by insurance claims, as the staff learned, and the collection is currently inaccessible while a new housing is designed and made. The school also has a substantial collection of plaster casts of famous sculpture, including three copies of the Venus de Milo. Insurance funds were diverted to treatment of certain casts, leaving the remainder to the care of volunteers, and one of the burnt Venuses was deemed not worth the effort. However, the blackened cast has captured the media’s imagination and public support for its treatment is high. In addition, the library was furnished with brass light fixtures, which became an intersection of the building fabric and the collections; many were dissociated in the disaster, and salvaged pieces will be reunited when possible. The school archives provided the original sketches of the lamps’ design and construction, and these will be used to restore the lights to functionality.
Lessons learned? Perhaps one of the biggest takeaways is that archival collections and other records can be valuable resources in recovering from a disaster. The better the records of a heritage building and its collections, the better the disaster response will be. Knowing the extent of one’s insurance cover is also important, as the Glasgow School of Art learned with regard to the textile collections. And as Christie and MacKinnon demonstrated with their remarks, in cultural heritage disaster response, everything is connected—from the fabric of the building to the collections housed within. In the end, Christie and MacKinnon advised attendees that choices made in disaster response will always be limited by the circumstances of the disaster; the best decisions to make are the best decisions you can make.

44th Annual Meeting – Collection Care Session, May 15, "Spoiler alert! Planning around the pitfalls of construction projects" by Jeffrey Hirsch and Angela Matchica

Construction projects have been on my mind lately and I thought this would be a good complement to Angela Chang’s presentation about her experiences during two major construction projects at the Straus Center (she spoke at the Conservation & Exhibition Planning: Material Testing for Design, Display, and Packing conference in DC in November 2015). Jeffrey Hirsch and Angela Matchica from Ewing Cole (an architect-design-engineering-planning firm) put together a clear and useful review of how conservators and collections care professionals can be active participants in a construction planning process. They took turns speaking, with Jeffrey giving an overview of each issue or area of collaboration, and Angela providing the in-practice examples from her experience as a lighting designer. The concrete examples were helpful in illuminating how collaboration goals can be translated into actual practice and decision making.
Jeffrey emphasized the complexity of the team on both sides of a museum construction project, with a wide variety of interests being represented. He noted that while those from Facilities departments are probably used to talking to architects and designers, the rest of the museum representatives may not initially be as comfortable, but need to make the time to stay at the table and speak up whenever they have questions. The slide below started out as just two dots – Design Team and Museum – and then grew and grew to encompass all the different roles that are part of the discussions around planning a new space or changes to an existing space.
Hirsch Matchica people at the table
In this diverse group, achieving consensus can be difficult, and knowing everyone’s individual needs is important. Angela discussed one instance in which repaired dinosaur skeletons were going on view, and light levels were initially assessed for the bones themselves, though it turned out that the most sensitive material present was the adhesive in the repairs. She also mentioned that they built a standalone mockup so that lighting levels could be experienced by all stakeholders, to get a real sense of what the space would feel like with different lighting, to achieve consensus. I thought this slide was helpful in illustrating all the sub-questions from different stakeholders that are a part of one major design decision.
Hirsch Matchica problem statement
Jeffrey noted that what looks like one construction project is really a number of simultaneous and interdependent projects – structural, exhibit design, conservation, and so on – all coming out of basically one pot of money. Scheduling all of this was likened to a symphony, in which it’s very difficult to get the multiple instruments to finish the piece at the same time.
Hirsch Matchica multiple projects at once
As always, communication was underscored as the most essential element. Each group should be aware of how the other groups are progressing, and know if someone’s end date is shifting, and what that means for all the others. On this point, he stressed how important it was to have a contingency amount of funds specified in the budget very early on. Changes cost a lot more at the end then they do at the beginning, so it’s also important to assess all your options early on and make choices then, with full information about the long-term costs of each option. Here, Angela presented the choices between various types of light bulbs, some of which are low cost but require frequent replacement, while spending a bit more at the beginning can lead to major savings in time and materials later in the life of the building – value engineering.
Hirsch Matchica bulb choices
The end message for all involved parties was to stay at the table, attend all meetings, read and familiarize yourself with all the minutes and notes, and keep track of what decisions are made. No sweat! I still feel like the only way to really know how to predict and prepare for all the things that can go wrong in a construction project is to go through one and learn from your own mistakes – but it was great to hear from the other side of the table, especially from a team that has a real sense of the wide-ranging and diverse concerns of working in a museum setting and the energy to work towards collaboration.

44th Annual Meeting, Paintings Session, May 17, 2016, “Experimental study on merits of virtual cleaning of paintings with aged varnish” by Giorgio Trumpy and John K. Delaney

 
Giorgio Trumpy presented interesting work he has been conducting on the “virtual cleaning” of paintings at the National Gallery, Washington, D.C. as a post-doc with John Delaney. He described a mathematical/- computer model which is being developed to predict and represent what a painting would look like after the removal of a yellowed varnish. The idea is not to replace the conservator, but to provide a tool in helping conservators visualize the results of such a treatment.

GIF_VanHuysum_animated
Click on the animated .gif image to see the difference in before, virtual cleaning, and real cleaning (after).

The model makes use of the contribution of the scattering (diffuse reflectance) of light from the surface of a painting with and without an aged varnished, after application of a fresh varnish, and from the interface of the paint layer and the varnish surface itself. Measurements were made on two paintings to obtain values for use in the model, and the optics of the yellowed varnish itself was estimated by measuring the transmittance through a solvent containing the dissolved yellow varnish.
The results give a pretty good indication of what the painting might look like after removal of the vanish. Click on the image* to see the animated .gif (it worked on my computer). There are differences with the paintings however as can be seen comparing the virtual cleaning image and the after (real) cleaning image. Trumpy thinks that the differences are due, among others, to the fact that the model does not account for local variations in varnish thickness or aging, and the use of the transmittance values for the yellow varnish as measured through the solvent.
In a follow-up e-mail van John Delaney I understood that the goal of the work is to better understand which factors are important for this kind of modelling work, and also to determine the limits of what the model can do. Still, I found it fascinating to see how far they had gotten.
______________________
* Image courtesy of G. Trumpy and J. Delaney, Scientific Research Department, National Gallery of Art, Washington, D.C.; detail from “Flowers in an Urn” by Jan van Huysum, c. 1720/1722, oil on panel,
79.9 x 60 cm.

44th Annual Meeting – Saving and Preserving Family and Local History from Natural Disasters: Addressing Challenges from the Recent Earthquakes in Japan

This panel, presenting on the response to the tsunami in Japan in 2011, was composed of Masashi Amano, Kazuko Hioki, Tomoko Yasuda Ishimaru and Daishi Yoshihara. Drs. Amano and Yoshihara are both historians, and Ms. Yasuda is a conservator in private practice in Tokyo. Ms. Hioki is a conservator in the United States, and special thanks goes to her for her excellent translation during the question and answer sessions.
The presentations brought to light a number of interesting cultural differences that may be surprising to an audience from North America. The majority of public records (according to Dr. Yoshihara, the number may be as much as 90%) are held privately, rather than my public or governmental institution. This means that when a disaster occurs, it is often difficult to find out who is a stakeholder, what records are involved, or even where those records are. Often, historic sites contain records, but just as often records, historical and modern, can be found in attics and in community centers. This would include tax information, birth and death records and legal documents.
The prevalence of natural disasters in Japan makes creates another important difference.it It si very difficult for insurance companies, a very conservative business in Japan, to provide coverage in the event of a natural disaster. This means that public institutions and private collections cannot rely on the insurance industry to pay for recovery companies, and as a result, recovery companies have a much reduced presence in Japan. The end result is that, when natural disasters occur, Japanese individuals and institutions cannot rely on the same emergency response structure that we in North America.
The presenters spoke about their work helping disaster recovery after the 2011 tsunami, but much of their presentations focused on Shiryo-net (the Miyagi chapter which responded to the tsunami has an english language blog). Shiryo-net is a grassroots organization of historians and volunteers who respond to disasters specifically to deal with conservation issues, such as finding out where in a town records may be kept, rescuing those records, and performing triage treatment whenever possible. Shiryo-net formed after the Hanshin-Awaji earthquake in 1995, and has grown to 24 regional chapters across Japan.
Since its inception, Shiryo-net has focused on saving those 90% of documents that are not in museums, libraries and archives. Its activities are entirely funded by membership dues and donations. The organization first came into contact with conservation on a more formal basis in the wake of a flood in Hyogo prefecture in 2004. During this disaster, they were able to work with conservators to develop first aid treatments that could be taught easily to volunteers, and the difficulties they encountered encouraged them to host workshops and become a center of volunteer training for conservation volunteers. When another flood occurred in Hyogo in 2009, the response was much quicker, and the level of care given to documents was much better. Shiryo-net is now an experienced organization, and focuses on leadership training and volunteer education as well as disaster response.
The second major focus of the talks given by the presenters was on Shiryo-net’s response to the 2011 earthquake and Tsunami. The obvious difficulties of working in a disaster area were present, as were the difficulties of working with a large, non-professional force. Over the course of the recovery, Shiryo-net worked with over 5,000 volunteers, and had to develop techniques for training, supplying and managing such a large and ever-changing population. Because of the scale and scope of the disaster, salvage operations were ongoing as much as three years after the disaster. Since the tsunami, Shiryo-net has rescued more 70,000 items, with at least 50,00 items still in storage waiting to be treated.
The presentation was informative and engaging. It was interesting to hear about the different challenges faced in a different country, and how those challenges have been met or overcome. I would like to thank the presenters again for being so forthcoming with their talk materials as I prepared this post.

44th Annual Meeting – Photographic Materials Session, May 15, “Analysis of Historical Tintype Plates: Materials, Methods and Manufacturers” by Dr. Corina Rogge

Dr. Corina Rogge, the Andrew W. Mellon Research Scientist at the Museum of Fine Arts, Houston, presented a very interesting (and thorough) talk on the “Analysis of Historical Tintype Plates: Materials, Methods and Manufacturers” giving a brief overview of the tintype process and the ongoing project to characterize their material properties. The analysis was undertaken on a study collection involving 226 unknown tintypes.
Despite the popularity of the process, there were only three patents filed in its history, and how they were actually made is poorly known. Hamilton Lamphere Smith and Peter Neff first patented their process for a collodion image on a japanned surface in 1856. Their melainotypes, so named from the Greek melano, or black, consisted of a varnished image layer on the japanned iron plate, also varnished verso. Peter Neff was interested in the commercial properties, including japanning purchased plates. He sold prepared plates, as well as licensing the process for use. The plate itself was not patented. Victor M. Griswold patented a competitive process also in 1856, using bitumen on an iron plate, and called them ferrotypes to indicate the iron content. There were eventually several plate manufacturers including Neff, Griswold, Dean & Co., and Phenix; however, only Neff and Griswold stamped their plates.
Tintypes were affordable, durable and accessible, and became widely popular in mid-1800s America, and really came to represent the middle class. They are not as common in museum collections, but a large number survive as family and historical items. Dr. Rogge noted that the market and development of the process were strongly economically driven, and the producers found a need to create trends to keep their edge or drive sales. For example, Griswold began to name and sell imperfect plates as “eggshell,” in addition to glossy plates.
Dr. Rogge’s study sought to determine whether different manufacturers used different materials, and if so, whether they be differentiated and dated. X-ray fluorescence spectroscopy (XRF) analysis revealed mostly iron, as would be expected for the plate. A smaller number contained manganese, but didn’t seem to correspond to a trend. There were no major differences in thickness, aside from very early Neff plates being thicker. These very were fairly quickly thinned down to the typical size, making them cheaper to manufacture and mail. Griswold used thicker plates only very briefly.
Organic analysis was carried out on the japanning layer by pyrolysis gas-chromatography (py-GC-MS). There were no particularly unusual result, as might be expected for a commercial process. Drying oil was the most common component, then pine resin, followed by a small number containing shellac. Asphaltum, which Dr. Rogge pointed out is difficult to work with, was found in fewer than 10% of the plates although it is mentioned in two of the three patents ever filed.
Microscopy determined the most common pigments of the japanning layer to be carbonaceous blacks, as given in the Neff patent, and iron earth pigments as given in the later patent. Plates were sometimes advertised as chocolate or black, and an effort was made to differentiate between the two. Colorimetric analysis ignored the CIE b* parameter (blue-yellow) to accommodate the assumed yellowing of the varnish. CIE a* when checked against manganese didn’t correlate. In attempting to differentiate the bare support versus japanning layer with support, the thickness of the japanning layer seemed to have much more influence. However, Dr. Rogge believes further study may prove chocolate plates (more red) correlate to the use of iron earth pigments in the japanning layer.
Relatively few plates had a single japanning layer, while many had two or three. Though the practice is not indicated in any of the patents, it is mentioned in articles of the time on how to make tintypes. Though multiple coats would increase the cost and difficulty of production, they would provide a smoother, glossier surface. In addition, a more pigmented bottom layer (a ‘face coat’) might serve to isolate and protect pigments from reactive image silver, and approximate the depth of an ambrotype by allowing more light to pass through.
Dr. Rogge pointed out that the project needs more data but points to the possibilities of trends and potentials for identification. She noted also that the actual plates varied significantly over time, and differed between manufacturers and particularly from the patented processes. For example, Neff plates may have more layers as time goes on, and Griswold plates may be associated with profiles containing asphaltum, drying oil, pine oil and shellac. Such an ability to profile the plates would give the possibility of identifying and dating unknown plates.

44th Annual Meeting, Photographic Materials Session, May 17, 2016, "Methods for Cleaning Brass Mats from Cased Photographs" by Christophe Vischi, Ariane Lalande, John McElhone and Chloé Lucas

Christophe Vischi and Ariane Lalande presented a talk on practical tests they conducted to determine how to clean brass mats of photographs from the collection of the Colby Curtis Museum, Stanstead, Quebec. These mats suffered from multiple corroded spots (which I know as pitting corrosion from industry), containing stable Cu2O cuprite and active atacamite Cu2Cl(OH)3. They compared two electrochemical methods and the use of an ion exchange resin to treat the mats:
– spot electrolysis using an EDTA electrolyte and at 9 Volts,
– brushing an glycerine electrolyte on the object, wrapping it in aluminum foil and laying it a humid chamber
– use of the ion exchange resin, Amberlite IR 120 HM. This comes in the form of beads, which were applied locally on the object as a poultice using a fine brush.
The authors did not obtain good results with the electrochemical methods, with staining being a problem for the spot electrolysis, and a gray patina a result of the wrapping method. They chose the method using the ion exchange resin. It was found that grinding the beads before application improved the results. Very local cleaning was possible, and the solution could be rinsed off with a mixture of ethanol and water. Still, there were flecks left where the pitting corrosion was, but these could be retouched to match the finish. Care had to be taken to avoid staining uncorroded areas. The result appeared to be satisfactory, and they want to continue work on optimizing this method.
I would like to note that electrochemical methods should not be ruled out based on this paper. When performed properly, electrochemical cleaning can be used to clean most metals found in museums. C. Degrigny, among others, has demonstrated that local electrochemical cleaning can work under properly controlled conditions (cathodic potential/voltage), using the proper equipment, and electrolytes. The aluminum foil method might have worked if the objects were not wrapped (traps the reaction products), and the proper electrolyte was used. If I heard correctly, glycerin was used as the electrolyte, but it is non-conducting, so it could not have worked.

44th Annual Meeting, Architecture Session, May 16, 2016, "Protecting Stained Glass Windows from Vibrations Caused by Construction Operations" by Dean Koga, Erica Morasset and Michael Schuller

Dean Koga and Michael Schuller gave an interesting and useful talk on the protection of original Tiffany stained glass windows at the Congregation Shearith Israel in New York City during heavy renovation work there. The talk gave a clear outline of what they did and how others can prepare for such events. It should be noted that there was little warning between the time that the Congregation was informed of the work and the start of the work.
They carried out the following actions (which I would strongly recommend):

  1. Look for local engineering expertise in vibrations and the monitoring of vibrations. Michael Schuller represented this company.
  2. Look at existing (inter)national standards for the protection of buildings due to vibrations including those caused by construction work. These included building codes for New York City, international codes for France and Russia, and the vibration literature.
  3. Document fully any preexisting damage in the stained glass windows
  4. Look at the levels of current existing vibrations due to, for example, traffic, wind, opening and closing of the windows or doors. This showed that such events, as well as the opening and closing of the windows themselves were also a source of background vibration and shock.
  5. Determine limits for vibrations including a warning limit, and a limit where work has to immediately stop. These were 0.15 in/sec (3.75 mm/s) and 0.2 in/s (5 mm/s) for the low vibration frequencies expected.
  6. Negotiate with contractors to use more “gentle” construction methods. The contractors agreed to avoid using a wrecking ball for razing the old part of the synagogue, and to use augured piles for the foundation instead of pile driving.

The precautions were successful. No damage was found after demolition work, and only one new crack was found near an operable window. It was interesting to hear that wind pressure on the windows actually increased due to exterior protection. The authors were aware that the vibration sensor they used, a geophone actually designed for earthquake monitoring, was too heavy for the job, but time constraints limited their choices. A lightweight (several grams) sensor placed on the window frame or horizontal supports would have been better.
The authors recommended more studies on systems to protect stained glass windows, and testing to determine how much deformation/displacement such windows can tolerate. I would certainly agree with that.

44th Annual Meeting – Emergency Session, May 17, 2016, “Emergency Preservation during Armed Conflict: Protecting the Ma’arra Museum in Syria” by Brian Daniels and Corine Wegener

I wanted to attend this presentation because I couldn’t imagine what type of emergency response would be possible in a situation as horrific as the one in Syria.  When your life is in danger or there isn’t enough to eat, how can you think about saving artifacts or cultural sites?  What I learned from Brian Daniels’ talk was inspiring and thought-provoking.
Brian Daniels is the director of Research and Programs at the Penn Cultural Heritage Center of the University of Pennsylvania Museum. A primary focus of the Center is community archaeology, an archaeological practice dedicated to engaging local communities in the preservation of cultural heritage.  Could some of the practices of community archaeology be usefully carried over to a conflict zone?  How could a response to safeguarding Syrian heritage be local, empowering, and post-colonial? How could Syrian cultural heritage professionals be involved?
This thinking led to the creation of the SHOSI (Safeguarding the Heritage of Syrian Initiative) project where outside experts and Syrian professionals worked together to determine what might be saved and how it could be done.  Daniels gave three examples of the work undertaken by the team.
The first was at the Ma’aara Museum where there were numerous large Roman and early Christian mosaics installed into the fabric of the building.  Based on protocols developed to protect Leonardo’s Last Supper during World War II, the Syrian team faced the mosaics with a water based adhesive and fabrics readily available at Turkey’s equivalent of Home Depot.  Sandbags were placed in front of wall-mounted mosaics or on top of floor mounted ones.  The non-Syrian experts helped procure the necessary supplies.  The museum was bombed on two separate occasions, but the mosaics survived.
The second example was the intervention at the bronze-age site of Ebla known for a major find of cuneiform tablets in the 1960s.  Satellite images showed changes in the excavated structures, suggesting disturbance to the site as a result of looting.  The Syrian team confirmed that the mud brick buildings had been tunneled into.  They used concrete blocks and a mud mortar to help shore up the walls, and as a result the damaged walls did not collapse in the winter rains.
The last example was not a success story.  The 5th-century Church of St. Simeon Stylites is part of an important early Byzantine complex.  Armed groups were operating near the church and looters were digging in the complex for mosaics.  As the team was trying to decide what to do, the area was bombed and the church was damaged.
I am not an archaeological conservator, and one of the powerful aspects of the presentation was seeing images of these incredible Syrian sites.  And the extreme risks that Syrian heritage professionals were taking seemed much more real when you saw that their faces had to be blurred out in the presentation.
As with many talks at this meeting, Daniels and Wegener have been thinking about how our profession can be inclusive, responsive, and involved in the pressing problems of the 21st century.

44th Annual Meeting – Paintings Session, May 15, 2016, “The History, Technical Study, and Treatment of Francis Bacon’s Painting 1946” by Ellen Davis, Michael Duffy, Chris McGlinchey, and Lauren Klein

I am interested in artists’ involvement with the conservation of their pieces, and I love Francis Bacon’s paintings so I was happy when I saw that this presentation needed a blogger.
Francis Bacon considered Painting 1946 to be a break-through work.  It was purchased by MoMA in1948 two years after it was painted.  Because Bacon used pastel ground in water as well as oil paint, the painting almost immediately had issues with the media flaking and fading.
In 1959 and again in 1971 Bacon proposed scraping down the pastel and repainting the background.  In 1959 the museum was interested in this option, but for unclear reasons, Bacon did not end up reworking the piece.  In 1971 before Bacon’s retrospective at the Grand Palais in Paris, Bacon again offered to repaint the background.  This time MoMA did not want the artist to address the issues with his piece, but agreed that the painting needed conservation.
Before the Paris retrospective, conservator Jean Volker consolidated with gelatin and inpainted with crushed pastel.  Francis Bacon was thrilled with the results and believed that the painting had been given a new life.  He decided that he even liked the faded colors better.
Over the years, the pastel inpainting faded and no longer matched the original, gelatin consolidation residues turned gray, and there was continued flaking.  The painting again needed treatment. Given Bacon’s satisfaction with the 1971 results, it was decided that the goal should be to return the piece to its post-1971 treatment state, but using more stable materials.
Ellen Davis’ treatment involved removing the gelatin aqueously through tissue followed by silicone solvent cyclomethicone D5 (to avoid tide lines).  Lifting paint was consolidated with TRI-Funori.  Where possible the faded inpainting was reduced mechanically. The new inpainting was carried out with more light-fast pastels.
As Davis noted at the end of her presentation, this painting can only be as stable as its original materials.  It is fortunate that it is in a collection where it can be carefully monitored.