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…

AIC 41st Annual Meeting – Research and Technical Studies Session, May 31, “Artificial Aging of Paper-Based Cores Wrapped in Various Isolating Layers for use as Archival Storage Supports by Amy Williams and Catherine H. Stephens”

When faced with a budget dilemma for oversize mining maps storage, Amy Williams, project conservator at the University of Pittsburgh, asked herself “the $13,500 question:” Is there a benefit to using an archival 12” diameter storage tube core versus a non-archival 12” core wrapped with an isolating layer?
It would be easy to assume that archival cores were significantly better, well worth the extra $13,500. However, when faced with the substantial cost difference, Williams decided to conduct a scientific research project to determine the most cost-effective and preservation-friendly rolled storage system for the 5’ by 15’ maps of the Consol Energy Mine Map Preservation Project. She and her co-investigator, Dr. Catherine Stephens, presented their results on May 31, 2013 during the Research and Technical Studies Session of the AIC annual meeting.
If Williams and Stephens could prove that there was an acceptable, more affordable alternative to archival tubes, the news would be of great benefit to cultural institutions, collectors, and conservators. I was eager to hear their results.
Williams partnered with Stephens, Senior Research Scientist at the Art Conservation Research Center, Carnegie Mellow University (now at Yale University) for the investigation. They studied four types of tubes and six wrapping options suggested by conservators: no wrapping, polyester film, Tyvek, Marvelseal 360, heavy weight aluminum foil, and tissue paper buffered with 3.5% calcium carbonate. For the cores, they selected two archival tubes with different adhesives (sodium silicate versus a blend of polyvinyl alcohol and polyvinyl acetate), a non-archival core of kraft paper with an unidentified adhesive, and a Quik-Tube concrete pouring tube composed of recycled paper and a polyvinyl acetate/acrylic adhesive.
In the experiments, the maps were simulated by using Whatman #1 filter paper. The use of Whatman #1 paper versus historic papers was discussed in another 2013 RATS talk by Bill Minter and John Baty, “The Role of Polyester Film Encapsulation—With and Without Prior Deacidification—On Paper Degradation, Studied During Long-Term, Low Temperature Aging.” Minter and Baty chose historic papers for their research. I think it would add to our understanding if Williams and Stephens conducted a second phase of their research using commercially available papers or naturally aged historic papers to compare with the Whatman #1 results.
Their test samples, each consisting of a “map,” an isolating layer (or none), and a core, were aged at 90˚C and 50% relative humidity in an oven for up to 24 weeks.
The researchers’ first discovery was the unexpected impact of the adhesive, which caused staining on the tubes at the seam gaps between the narrow strips of paper comprising the tubes. This staining transferred onto the Whatman paper “maps.”
To prevent this problem, Williams recommended obtaining seamless tubes by asking the manufacturer to skive the edges of the paper. She also emphasized the importance of knowing the composition of both the paper and the glue of the cores.
I wonder how problematic the adhesive would be during a natural aging process or during a lower temperature artificial aging, and hope the researchers will consider exploring this in the future.
Williams and Stephens reported that the linen ties on the samples caused staining during the aging process. They switched to rare earth magnets, which caused no reported problems. Would a lower temperature during testing have prevented or reduced the problem with the linen ties? If this is a significant problem at all temperatures, linen ties may not be appropriate for rolled storage.
The experiment produced more unexpected results. The researchers evaluated the effects of the cores and isolating layers on the “maps” by measuring the chain scission of the cellulose, the yellowness, and the pH of the “maps.” I was surprised to learn that both the Tyvek and the Marvelseal 360 actively promoted degradation, yellowing, and a lower pH.
The aluminum foil, polyester film, and buffered tissue offered varying amounts of protection, depending on the type of core used. The best isolating layer overall was the heavy weight aluminum foil, and the best wrapper for the kraft tube was polyester film.
I wondered if the high temperature during aging might be responsible for the poor performance of the Marvelseal and the Tyvek, and whether the heat caused chemical changes within these two films. How much of the unexpected results overall was caused by the elevated temperature? Would similar results occur during natural aging at room temperature?
The researchers did speak about this issue. Stephens said that they chose the high temperature for artificial aging to ensure detectable changes, and stated that more research was needed lower temperatures.
From what I understood about the test results that Williams and Stephens presented, it seemed that wrapping a non-archival core with heavy weight aluminum foil could give comparable results to using an archival core. I would like to know more the amount of difference they saw, and hope they will offer a detailed discussion of this in their article about the research.
The results of their experiment have caused me to question my own assumptions about the storage materials we use. I hope Williams and Stephens will continue their valuable research, to determine what results are typical at lower temperatures and answer some of the other questions they raised during this first phase of the investigation.

39th Annual Meeting – Paintings Session, June 2, 2011, “A Neoclassical Mystery: The Technical Study and Treatment of an Iconic French Portrait” by Kristin deGhetaldi

There were three very interesting aspects of this presentation if you love the quality of high society French painting between 1775 – 1825… or there abouts:


First, Kristin gave a very nice art historical review of Jacques Louis David’s studio culture and influence, which included more than 400 students that studied directly with the master. She gave some really interesting comparisons between the styles of some of the students and David but ended up focusing on the work of a female student, Marie Benoist.


Second, Kristin focused on Marie Benoist as she presented the very interesting technical and historical study of a very intriguing “iconic” female portrait that was previously misattributed/unattributed and is logically attributable to Benoist, according to deGhetaldi’s research. Actually, I personally liked the portrait better than the David and other portraits that were shown for it’s interesting positioning and thoughtful mood. Flat out, it’s a great picture.


Third, the thorough conservation treatments of the portrait were interesting but not unusual. At the beginning of Kristin’s presentation of the portrait, I was hoping that she was going to let us see the differences through cleaning. I was not disappointed as the final conservation presentation and aesthetics were wonderful.

Portrait by Marie Benoist
The "Iconic French Portrait"


The plentiful photographs, of course, made Kristin’s presentation that much more enjoyable. And the thorough technical analysis with documentary microscopic studies of greens particular to that time period and location that will aid future researchers in authentication clues.


Contact Ms. Kirstin deGhetaldi at k-deghetaldi@nga.gov


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Scott M. Haskins

Fine Art Conservation Laboratories (FACL, Inc.)



(805) 564 3438