Location: Museum of Modern Art, New York, USA
Dates: October 31rst / November 1rst, 2013, 9am – 5pm
Target Audience: This workshop is aimed at researchers and conservators who want to be able to analyze their own laboratory data, and with a need for exploratory data analysis, development of predictive models and sample classification. No prior knowledge is required for this course.
Course Description: The course will cover the fundamentals of many commonly used Chemometric methods including Exploratory Data Analysis and pattern Recognition, Regression and Classification Methods (PCA, PLS, SIMCA,PLS-DA)and Data Pretreatment. Emphasis will be on applying these techniques in the contex
t of cultural heritage research.
The course will comprise lectures and hands-on activities. Computers will not be provided. Participants are encouraged to bring their laptops with demo versions of Solo installed. A 60 days demo license will be provided by Eigenvector to each participant.
About the Instructor: Dr. Donald Dahlberg is Professor Emeritus of Chemistry at Lebanon Valley College. Dahlberg earned a B.S. in Chemistry from the University of Washington and a Ph.D. in Physical Chemistry from Cornell University. After decades of doing research in the area of Physical Organic Chemistry, he got involved in Chemometrics while on sabbatical in 1988 at the Center for Process Analytical Chemistry at the University of Washington. There he learned chemometrics in the Bruce
Kowalski group (co-founder of chemometrics). Upon returning to LVC, he taught chemometrics to undergraduate students for over a decade. Although retired from the classroom, he continues do consulting and supervises undergraduate research in industrial chemometrics. He wrote and teaches this workshop so that those not fluent in matrix algebra can take advantage of the powerful tool of chemometrics..
How to Register: A registration form can be requested by email to ana_martins@moma.org. The deadline for registration is October 7th, 2013. Cost: $400 (includes course materials and refreshments). Participants’ number is limited to 10. For registration and inquiries please contact: ana_martins@moma.org
Category: Research and Technical Studies
Posts on research, materials & techniques used in and by conservators
AIC's 41st Annual Meeting, Paintings and Research and Technical Studies Joint Session, May 31, "Water in Oil Microemulsions: A Novel Cleaning System for Acrylic Paints" by Tom Learner, et al
This presentation summarized the collaborative research of the cleaning of acrylic paint films by the authors representing the DOW Chemical Company, the Tate Gallery and the Getty Conservation Institute. The aim of the research is to develop and educate professionals in the cleaning of complex, contemporary synthetic painting media. Early findings of this research have been presented at the AIC Annual Meetings in Los Angeles (2009) and Milwaukee (2010) and at the Cleaning 2010 Conference in Valencia. The components of these systems have varying effects on the medium: acrylic paint films are easily swollen in an aqueous environment, hydrocarbons have poor cleaning efficacy and on large colored surfaces there is a risk of tidelines. The surface character can be changed if extracts are removed.
Dynamic mechanical analysis of potential cleaning materials was conducted; the procedural process was described as “clamping” system that would provide uniform tension across the test film as it was dipped in solution. The displacement of the grips is measured as the paint film contracts upon drying. Acetone and water produced significant swelling, mineral spirits resulting in a flat line. Analysis was conducted using FTIR-ATR (Fourier transform infrared-attenuated total reflectance) spectroscopy on cleaning swabs indicating the level of surfactant material at the surface.
Trial microemulsion cleaning formulations were prepared by DOW and the Tate which were tested by conservators at workshops, including four CAP’s (Cleaning Acrylic Paintings) seminars presented in different cities by Chris Stravroudis. Resulting evaluations have contributed to further refinement of formulations for better compliance with performance criteria desired by conservators. Three classes of microemulsions were produced. All have an aliphatic hydrocarbon in a continuous phase. They incorporate different surfactants. The presence/level of an alcohol as a co-solvent is sometimes incorporated, as an alcohol is required in some systems to enable a stable microemulsion structure. One class of potentially useful formulations of water-in-oil microemulsion systems that are thermodynamically stable is being tested. They incorporate deionized water, a non-miscible hydrocarbon solvent (one being tested is hexanol/butanol (?)) and a surfactant in an attempt to remove grime without removing original material, namely surfactants used in the manufacture of these painting materials, which are known to migrate to the surface as they age. They offer the possibility of exploiting cleaning efficacy associated with aqueous systems but in a predominantly solvent environment where the micelles formed has the surfactant on the outside and the water on the inside. The pH in these systems can be varied using sodium chloride. The ionic strength of the solution should be compatible with the paint film; conductivity should be adjusted, as needed. A stable microemulsion will be clear, while an unstable one will be milky. Other components of the three series included a “green” surfactant, Ecosurf®, a promising new Triton material, Triton GR7, which is soluble in Shell Sol solvents, and the introduction by Richard Wolbers of silicon based cleaners. The latter material was reviewed by Chris Stravroudis in his article, “More from CAPS3: Surfactants, silicone-based solvents, and microemulsions”, WAAC Newsletter 34/3 (Sept 2012), pp 24-27.
The series of microemulsions are being extensively tested including the issue of clearance. A new publication on the progress of this research is expected in 2014.
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.
AIC 41st Annual Meeting – Research and Technical Studies Session, June 1, "The Role of Polyester Film Encapsulation – With and Without Prior Deacidification – On Paper Degradation by William Minter and John W. Baty"
William Minter and John Baty presented the results of this aging study of particular relevance to those of us working with archives and library materials. The hypothesis: “Encapsulated acidic sheets will degrade faster than unencapsulated sheets”. The question driving the testing was whether deterioration products from the paper can become trapped in the encapsulation, thereby accelerating further damage. In essence, do encapsulated papers “stew in their own juices”? I, for one, certainly would have assumed the answer to be “yes”. But the use of encapsulation as a means of support for brittle and fragile documents beats lamination with cellulose acetate, as would have been the practice decades ago. What else is a paper conservator to do?
Here is how this study proceeded: Minter and Baty acquired different naturally aged papers for use in this study of the effect of sealing papers between film. The papers were typical of those in archives, including bond paper, ledger paper and “onion skin”. All were acidic prior to oven aging. To more accurately mimic natural aging, the temperature used during aging was 45°C instead of the more commonly used 60°C and papers were heated for a longer period of time than normal. The aging “oven” was a sealed glass box with a circulating fan, heating element (pad?), and saturated salt solution that maintained a moderate relative humidity. If you have never been in the market for an official accelerated aging oven, you may be surprised to learn that they cost a pretty penny; we’re talking 10k! Fortunately, this alternative oven was significantly cheaper, and performed very well, consistently maintaining both temperature and RH.
The primary method of checking the papers’ deterioration was by measuring degree of polymerization with size exclusion chromatography. Shorter hemicellulose chains in paper samples after aging equate to loss of strength and flexibility in the paper, properties that were also measured and evaluated with fold endurance and surface pH. Results showed that the encapsulated samples DID NOT age faster than the unencapsulated samples, contrary to the hypothesis! (Maybe some of you will sleep better at night having learned this fact?) I believe this test concluded after 33 weeks. If appropriate, It would be interesting to learn if an even longer aging period would yield the same result.
A second set of aging tests with the same papers revealed that either washing in magnesium carbonate or using a non-aqueous spray deacidification product prior to encapsulation would be equally protective of some papers. It is not known how long this protection would last, however.
This was a very relevant study, the importance of which can be well appreciated by many in the field of archives and paper conservation. A repeat study of a broader range of papers, (maybe photographic?) could also yield very interesting results. For me, this is an essential paper to file under “must read, and read again”.
41st Annual Meeting – Research & Technical Studies, June 1, “Contemporary Conservation for Contemporary Materials” by Yvonne Shashoua
Attending a lecture by Yvonne Shashoua, Senior Researcher in the Department of Conservation at the National Museum of Denmark, was such a treat, since she is so well-known in the field of plastics conservation, and her session did not disappoint. Her calm, precise, and very approachable speaking style was impressive as she covered a scientific discussion on her current research into cellulose acetate degradation and its interaction with gas absorbents. Since she will be presenting her findings in upcoming journals, I will only briefly go over what I learned and what you missed at this Research & Technical Studies AIC session.
Shashoua began by reminding us that plastics comprise an increasing proportion of museum collections. Since it is difficult to detect plastic degradation until it reaches an advanced stage, a preventative approach, by either removing the factors causing or accelerating degradation, is usually taken. Gas absorbents (silica gel, activated charcoal, Zeolite 4A, and Corrosion Intercept) are frequently used in museum storage and display situations to create a microclimate by removing specific gases. She discussed how these materials are used and how they absorb pollutants, which I found very interesting.
Focusing on cellulose acetate, Shashoua discussed the mechanism of degradation (and the breakdown by-product acetic acid) and how additives (plasticizers and fire retardants, which are weakly bonded within the matrix) migrate out ultimately ending in shrinkage. She was curious why the degradation process even begins in a museum environment, which began her in-depth research project. Cellulose acetate, has been used since 1910, but by the 1960s could be found in many objects: imitation mother of pearl, cigarette filters, early Lego bricks, movie film bases and rayon. By conducting a systematic study on the adsorbents’ interaction with cellulose acetate, she has found some startling results. The adsorbents in some cases did slow down the onset of autocatalysis, however some also adsorbed the plasticizer and/or flame inhibitor, resulting in damage. Her results suggest that commonly used absorbents in museums are non-specific and ineffective for cellulose acetate and, by extrapolation, other plastics. She did rate the adsorbents on a sliding scale; so reading her more in-depth post-prints will be a good lesson and/or review for all of us. All this is startling news! An archival acid-free box might simply be the best defense. Wow. I cannot wait to read her in-depth post-prints and journal articles concerning this fascinating subject.
41st Annual Meeting – Contemporary Art Session, May 31, “Automating Classification of Historic Photographic Paper from Surface Texture Images,” by Paul Messier
For over ten years, Photograph Conservator Paul Messier has been researching the physical properties of historic photographic papers—fibers, thickness, optical brighteners, and manufacturer markings. Most recently, Messier and co-authors* have been working to objectively characterize the surface texture of papers as a means to classify individual photographs as well as collections.
Using his personal collection of over 5,000 historic paper samples along with photographs from the Thomas Walther collection at the Museum of Modern Art, New York, photomicrographs of each surface were captured using a “texture-scope” available only at the Library of Congress and the National Gallery of Art. The images were then processed to abstract the features of the paper and allow for easier measurement of the distance between each vector height (i.e. texture peak). The data were sent out to various engineering teams with the goal of creating affinity diagrams that reveal patterns of paper matches. Although each team came up with a different methodology for matching samples, they all achieved results very similar to human detection showing a spectrum of matches from the same sheet of paper, same package, or same manufacturer.
With these successful results, Messier hopes to continue collecting images to be stored on an open-access database. Eventually, institutions and collectors should be able to upload their own photomicrographs and search within the system to discover affinities across a collection. This information about the paper’s manufacture can then be applied to connoisseurship and conservation purposes.
*This project was a collaboration between Paul Messier, Richard Johnson, James Coddington, Patrice Abry, Philip Klausmeyer, Andrew G. Klein, Eric Postma, William A. Sethares, Sally L. Wood, and Lee Ann Daffner. To read more, please see the studies listed on the Paul Messier website.
41st Annual Meeting – Objects Session, May 31, "Beyond the Visible: Macro and Micro Analytical Forensic Imaging for the Documentation and Investigation of Archaeological Objects,” by Alexis North and Dr. Ioanna Kakoulli
There are two things you should know up front before you read this post. 1) This talk was fascinating. 2) I am not going to do it justice. I couldn’t take notes quickly enough and it didn’t help that I was frequently mesmerized by the beautifully colored images.
This paper briefly reviewed current methods for digital analytical imaging using visible, ultraviolet, and infrared light, but its true focus was on exploring and adapting technology from crime scene investigation for use in object examination. Specifically, the authors looked at the use of an alternative light source (ALS) combined with a different filters on a modified digital single-lens reflex camera (DSLR – modified by removing the UV/IR blocking filters). The ALS allows the user to choose specific wavelengths of light for illumination and, by using filters on the DSLR, reflectance/fluorescence can then be captured between 350nm and 1000nm. In this case, a Mini-CrimeScope 400 ALS was used along with a modified Nikon D90.
Multiple projects were featured to show the capabilities and limitations of the technique, all focusing on the investigation of archaeological ceramics. The authors began by creating reference panels of expected ancient pigments and binders, as well as of potential modern materials including adhesives. They then experimented to find successful combinations of excitation and emission. For one of the projects used as an example, an ancient Greek incense burner with a figure of Nike, this method of investigation was able to identify Egyptian blue and madder lake pigments. In this example, illumination was in the green spectrum and capture was in the red and vice-versa (if I’m remembering correctly). On a Roman figurine, the technique identified madder lake, but also pointed to the need for further testing of a green pigment which did not fluoresce (it turned out to be green earth). Additional examples included a Pre-Columbian ceramic and two Italian ceramics.
In summary, this paper demonstrated that forensic photography with a broadband light source can successfully be used for qualitative identification of a variety of ancient and modern materials. What’s exciting about this (at least for me) is its potential application to archaeological field settings. After all, crime scene investigation happens entirely “in the field” and this technique is completely portable. It also promises to be relatively simple once successful combinations are worked out for different materials. The ALS price tag is not exactly cheap, and the cost is likely to vary a bit depending on who’s buying (police department, university, etc.), but at roughly 15K it is in a more affordable category than, say, portable X-ray fluorescence. Plus, you end up with visually appealing and instructive images, which would frankly be great in both scholarly publications and museum didactics.
This paper also highlighted (for me) the debt we owe to graduate students like Alexis North (currently at the UCLA/Getty Program in the Conservation of Archaeological and Ethnographic Materials) and faculty like Ioanna Kakoulli (also at UCLA in the Materials Science and Engineering Department and Chair of the Conservation Program). Where would we be without graduate student research? Many of my archaeology colleagues will be delighted to know about this non-destructive possibility for investigating objects in the museum and in the field.
41st Annual Meeting – Book and Paper Session, June 1, “Testing the Waters: Applying New Techniques to the Cleaning of Acrylic Paint Film by Amy Hughes and Daria Keynan”
New York-based paper conservator Daria Keynan and Amy Hughes, third-year graduate student at NYU Institute of Fine Arts, shared exciting new contemporary cleaning techniques that have the potential for more effective and efficient treatment of paper-based objects by custom-matching the pH and conductivity modular stock solutions to the original object. This presentation was a wonderful and inspiring cross-specialty exploration of how paintings conservation techniques can be applied to paper conservation – and who doesn’t want more tricks up their sleeve?
Keynan was first introduced to the concept at the 2011 CAPS (Cleaning of Acrylic Painted Surfaces) workshop at the Museum of Modern Art. (I am now kicking myself for thinking that these workshops wouldn’t necessarily apply to my work as a book and paper conservator, so jealous!) To date there have been four innovative series of CAPS workshops supported by the Getty Conservation Institute to further the dialogue between theory and practice among conservation scientists and conservators as well as to introduce the concept of modular cleaning systems. Struck by her experience at the 2011 CAPS workshop and impressed by their use for treating acrylic paint films on art on paper, Keynan has further explored the use of pH and conductivity customization for other areas of paper conservation.
The CAPS workshop introduced several different cleaning techniques to minimize removal of surfactants when cleaning acrylic film surfaces. Acrylic paint and modern materials are scary (my word, not theirs.) Emulsions are often complex with many proprietary and artist-introduced ingredients. Colors react differently after drying, in treatment, and as they age. Some colors may be more sensitive to chemical and mechanical cleaning than others. Surfactants and other soft solids may never solidify, creating a tacky surface that can attract dust and grime. Conservation treatment, particularly aqueous treatment or mechanical cleaning with damp cotton swabs, can introduce immediate disfiguration like abrasion or swelling. Readily soluble surfactants can leach to the paint film surface or verso of the paper substrate. Treatment can also jumpstart deterioration that is not apparent until the future due to unknown chemical and mechanical consequences.
Of the many cleaning techniques available within contemporary conservation, Hughes and Keynan limited their presentation to the customization of pH and conductivity as a more finely-tuned and safer aqueous cleaning technique. They shared their methods by highlighting the treatment of works of art on paper brought to the Daria Keynan Paper Conservation in Manhattan for treatment where adjusted water – tweaking the pH and conductivity of the deionized water – was a key factor of success.
In the Garden (1986) by Paula Rego was surface cleaned to reduce dust and embedded grime altering the surface sheen. After dry cleaning with cosmetic sponges, Hughes tested various acrylic paint colors for pH and conductivity testing. Cylindrical pellets of cast agarose gel (recipe and supply information to be published in their BPG Annual post-print) were uniformly shaped with a medical-grade biopsy punch. (Heed Hughes’ warning, online image searches for “biopsy punch” are not for the weak-stomached!) The agarose pellet, acting like a poultice, was placed in contact with the acrylic paint film for 45 seconds to absorb the surface pH and conductivity. Agarose was selected because it imbibes the surface readings without visibly swelling the paint with excess moisture as in more aggressive techniques like local, direct application of deionized water. Keynan explained that the contact time of the agarose pellet can be matched to the estimated treatment time so that testing parameters can meet real-world treatment situations, increasing the predictability and reproducibility of testing results.
The pellet was transferred from the paper surface to the well of a pocket-sized, hand-held pH meter (Horiba Laqua pH Tester from Cole-Parmer) to record the pH of the paint surface. A droplet of deionized water was then placed on the pellet and transferred to another pocket-sized, hand-held conductivity meter (Horiba B-171 Twin Conductivity/Salinity Pocket Tester from Cole-Parmer) to record the conductivity of the paint surface. (As someone who absolutely dreads calibrating our cumbersome pH meter I was overjoyed to hear how easy these were to use – my purchase order request is already submitted.)
The conservators used the recorded pH and conductivity for a given area of the painted surface to identify the optimal working solution for cleaning. They selected from among a variety of premixed stock solutions that were created according to the CAPS workshop directions using deionized water, glacial acetic acid, and ammonium hydroxide in a range of ph 5-8 and conductivity 1000-6000 µS (micro Siemens.) Once mixed, the stock solutions can be stored in the refrigerator for up to several months. Keynan also reported that they often add several drops of an antimicrobial preservative for a longer shelf life.
The embedded material and dust on In the Garden released easily with 3-4 passes of lightly damp, pre-blotted cotton swab rolled over the surface. Hughes warned that since acrylic film is susceptible to abrasion it is important to monitor the paint surface during treatment. Cotton might not be appropriate for all acrylic surfaces so additional experiments with different swab materials may be useful. Similar success was seen in the mold removal and stain reduction of Maquette for Smoking Cigarette Relief (1983) by Tom Wesselmann.
Since Superstorm Sandy hit New York City in October 2012, Keynan’s studio has seen many complex treatments because of the unusual and unknown composition of the storm water which was often contaminated by sewage (uh, gross.) Many of the paper-based objects were stained with tidelines that were difficult to remove and fluoresced brightly under UV. Standard paper conservation techniques often visibly removed the tidelines but were deemed unsuccessful since under UV they shifted along the paper fibers or sank but were not completely removed from the paper support. She related that altering the pH and conductivity of her treatment water dramatically improved treatment results. Removal of the fluorescing blue tidelines (both external and internal) was achieved by local application of the adjusted water and using fumed silica poultices to block the formation of new tidelines.
The last example Keynan shared was a sample of naturally aged 2-ply paper board. (This was exciting, anyone else ever stare blankly at a nasty tideline on an illustration board and just sigh?) Traditional and adjusted treatment waters were applied with cotton swabs in several passes to clean the surface with varying results. Traditional deionized water cleaned less and was uneven, leaving a soft and vulnerable surface. The solution set at pH 6.6 and 6,000 µS glided more easily and had more even results. It also felt more controllable when working. The third sample solution set to pH 5.5 and 14,000 µS gave the most effective cleaning but in real life would probably not need three passes. After drying, the surface readings for all three areas had almost identical conductivity and pH readings.
Keynan concluded that by matching a pH- and conductivity-adjusted solution to the surface of the object it is possible to create a near chemical equilibrium at the surface to eliminate leaching from or depositing into the paint film. In treatment, using adjusted solution equals maximized cleaning efficiency with less wetting out of substrates, less pigment transfer, less repeated action, less loss of surface texture, and reduced distortion of the working area. Conservators have always adjusted pH for various uses, but by measuring the conductivity we can tailor our treatments to the physical needs of the object material with more refinement and subject it to less invasive treatment. Adjusted waters are an incredibly useful tool for improving and refining treatments in our conservation practice.
Hughes and Keynan’s presentation was an approachable and exciting take on the contemporary research going on in the field of conservation science and paintings conservation, especially as led by Chris Stavroudis (freelance paintings conservator in Los Angeles) and Richard Wolbers (Winterthur/University of Delaware Program in Art Conservation) in, well, all things related to cleaning painted surfaces and the Modular Cleaning Program.
Other presentations at the AIC meeting in Indianapolis such as “Mass Spectrometric Imaging of Acrylic Emulsion Paint Films: Engineering a Microemulsion-Based Cleaning Approach” (Paintings + Research and Technical Studies Thursday, May 30) show that the MCP and CAPS research continues. During the question-and-answer period Dr. Anthony Lagalante (Villanova University) shared that he and Stavroudis had recently recorded a video about using and calibrating the meters – it was on the cutting room floor, but will be posted to the CAPS website soon. Lagalante also sent me a link to their illuminating Studies in Conservation article that is currently available as a pre-print:
C.E. Dillon, A.F. Lagalante and R.C. Wolbers “ Aqueous cleaning of acrylic emulsion paint films. The effect of solution pH, conductivity and ionic strength on film swelling and surfactant removal” Studies in Conservation 57(1), (2014). http://www.ingentaconnect.com/content/maney/sic/pre-prints/2047058412Y.0000000076
The concept presented by Hughes and Keynan in “Testing the Waters” has the potential for wide application for all book and paper conservators. Working with stock solutions is a fast and economical lab practice. Customizing treatment solutions increases the workability and effectiveness of the treatment. Many of us in the room instantly coveted the easy-to-use digital meters as we thought of the hassle of calibrating traditional models. I’m intrigued by how this research can be applied to aqueous treatments meant to introduce alkaline reserves to acidic paper.
This was a welcome multi-disciplinary presentation that encouraged conservators from other specialty groups like PSG and RATS to attend the BPG program. I am not alone in hoping for more presentations like it at future meetings so we can all benefit from the exciting things happening in all areas of our conservation community.
41st Annual Meeting – Research and Technical Studies Session, May 31, “Examination, Technical Study, and Treatment of Funerary Stelae from the Roman-Egyptian Site of Ternouthis” by Caroline Roberts, LeeAnn Barnes Gordon, and Cathy Selvius DeRoo
Caroline (Carrie) Roberts presented an interesting talk about a multi-year collaborative project that demonstrates the real impact that surveys and technical studies can have on collections. In less than two years, the authors were able to survey a collection of 200 limestone stelae, assign treatment priorities, identify the agents of deterioration, suggest environmental guidelines, carry out treatments, and develop an informed treatment protocol.
The project began with the survey of the collection of limestone stelae by then 3rd year intern LeeAnn Barnes Gordon and continued as part of Carrie Roberts’ fellowship project at the Kelsey Museum. LeeAnn and Carrie collaborated with scientists in analytical laboratories at the University of Michigan and at the Detroit institute of Arts, including co-author Cathy Selvius DeRoo. Through their hard work and successful collaborations, the authors were able to accomplish an impressive amount and significantly improve the condition and long-term preservation of this invaluable collection.
Carrie first introduced the history of this collection of funerary stelae excavated in 1935 from the Roman-Egyptian site of Terenouthis. You can find some of this info on the Kelsey website here… and here:
She then spoke about the condition issues identified during the survey, which included stone delamination, surface powdering, biological staining, and peeling, darkened coatings. There were several types of salt efflorescence present including spiky salt crystals and more round gypsum like-salts. Spot tests identified chlorides and sulfates. Interestingly, research conducted into the archival holdings of the museum produced some incredibly relevant information regarding the past treatment of the pieces. A transcribed 1941 lecture by the archaeologist indicated that Duco cement was used to stabilize the stelae as they were excavated. The presence of cellulose nitrate was later confirmed using FTIR on samples of the darkened and peeling coatings.
As a result of the survey, approximately ¼ of the collection was determined to be high priority for treatment. These stelae received further study to characterize the deterioration and identify a treatment protocol. Testing was carried out using a barrage of analytical techniques including FTIR, XRF, XRD, specimen culturing and DNA analysis. The results allowed identification of soluble salts (calclacite- a calcium chloride acetate salt produced from interactions with offgasing materials + halide salts), characterization of stone properties (clay component within limestone- possibly responsible for delamination), and ID of the biological growth (black staining identified by DNA as Epicoccum nigrum of the class dothideomycetes, lichen not identified- no DNA present).
The treatment protocol that was developed through testing included:
-Consolidation of the limestone with CaLoSil (150nm particles of lime hydrate Ca(OH)2) in n-propanol. Testing was conducted using CaLoSil, Paraloid B-72, and Conservare (Ethyl silicate) consolidants. CaLoSil was most successful as it reduced powdering after 1 application without darkening stone. It is presumed to penetrate deep into the stone due to the small (nano) particle size.
-Structural stabilization using Paraloid B-72 (in 85:15 ethanol/acetone) injected into delaminating cracks. Not many of the stelae had extensive delamination but Paraloid B-72 was found to successfully stabilize cracks and areas beginning to delaminate.
-Desalination by poulticing with Arbocel paper pulp. This method was considered challenging/problematic and so the environmental controls were considered the best method of preventing future problems from soluble salts
-Coating reduction was accomplished by applying acetone followed by blotting.
-Biological staining was reduced by swabbing with ethanol; however, this was not found to be fully effective.
-Environmental parameters were set based on the equilibrium RH of the identified salts. The recommendation was to stay below 75% humidity, which is the equilibrium of halide salt and below that of calclacite (79%).
Carrie finished with some questions for future research, including: how is the CaLoSil distributed in the limestone after consolidation? What is the nature of the clay component in the limestone? What are the possibilities for reduction of the biological staining? And what is the best method for treating the stelae that had been stabilized with cyclododecane in 2009 when the collection was relocated to the current storage area.
Overall a very informative talk that hopefully will inspire similar in-depth survey and treatment projects!
41st Annual Meeting – Objects Session, May 30, “Establishing Conservation in an Unconventional Venue in Okinawa” by Anya McDavis-Conway
Ms. Conway’s paper presented multiple themes: the establishment of a new conservation lab, brief history of Okinawa, and cultural materials and their subsequent materials research and treatment. What is particularly different about the first theme is that the Conservation Laboratory was begun without a museum collection. The laboratory was established within the Okinawa Institute of Science and Technology (OIST) – a new, international research university staffed with 50% Japanese and 50% international staff. OIST applies advanced technology while using an interdisciplinary approach to higher education, and includes giving back to the Okinawan community in its mission statement. OIST President Jonathan Darfan was interested by the merging of art and science and wanted the conservation lab to be an important part of community engagement. Thus, with the establishment of the conservation laboratory, it was incumbent upon the conservator to find her museum collection partners.
Anya described this process as “setting up conservation in reverse”, and stated that the Okinawans were rather suspicious of her. I can believe their skepticism: “why would I want to had over my collections to a non-Okinawan” (prevalent in an island with a history of occupation) or: “Why are you doing this for free?”. Anya took time to visit the museums, got to know the only Okinawan conservators, a paper conservator named Toma-san and his son. She learned from him and other museum staff that all other treatments would either not get done or would be sent off the island (likely to Japan). Occasionally there was someone on Okinawa who would do lacquer repairs, and I wondered if they would be the gold repairs that we see on Asian ceramics sometimes.
Eventually Anya found two partners in the Yomitan Village History Folklore Museum, a small historical museum focusing on the small port of Yomitan. The other was the Tsuboya Pottery Museum. In the Yomitan museum, there was a definite need for collections improvements and conservation. The museum is located next to Zakimi Castle, which meant that there were also archaeological finds, in addition to historic, in the collection. There is also a traditional house, which was presented kind of like a period room (but house).
Tsubo means pottery in Okinawan (the Tsuboya Museum), and the curators there are very interested in pottery technology. Anya’s lab and connections in OIST are a perfect fit for their interests, and she discusses, later, the pottery research project they begin together.
Once Anya began getting treatments, she quickly realized that she needed more space than her 1/2 counter in OIST’s biology lab that she was given initially. I must think that they intended to provide more space, but perhaps wanted to wait until the projects actually came. OIST ultimately provided a decent lab space and some analytical equipment. Anya worked with the physicists to obtain such equipment: a Raman with a horizontal exit so objects can be placed next to it for analysis without sampling them, FTIR with ATR and, coming soon, a p-XRF. Jennifer Mass, the scientist from the Winterthur program, was also able to consult, in person, in the analytical set-up.
Interesting investigations were discussed. The first described looked at the leather on sanshins, which are three-stringed instruments that look a little like a banjo. They were originally played at the Royal Court, but now are played by more and more people. The sound box of the sanshin is usually covered in python skin, which is imported from the mainland. The two that were brought into Anya’s lab, however, were not made with python. Their origin was not easily detectable, so Anya worked with Sasha Mikayav, a scientist at OIST, to look into DNA sequencing for identification. The skins were ultimately too contaminated to provide good data, and Sasha recommended liquid chromatography – mass spectrometry instead. They prepared a sample from a cowhide from a music store as a control/test, and this was successfully identified as bovine. They will analyze other types of skins as they obtain them, and then test the sanshins after. But the fragile leather could wait no longer, and losses were filled with Japanese tissue toned with Golden acrylic emulsion paints and tacked in place with methyl cellulose. She made appropriate storage boxes and mounts for the sanshins after treatment because she thought it would begin a conversation about collections housing. I am curious if this worked, as it was an interesting decision.
The other major project begun is the pottery analysis project undertaken by Anya, OIST and the Tsuboya Pottery Museum. They are beginning to characterize pottery – both individually and as a group – using pXRF and XRD. They will be working with an Okinawan geologist to look at sources, tempers and inclusions using thin sections and traditional petrography. This project is the beginning of a long collaboration, as Okinawa has a long history and tradition of pottery making, and it has never before been systematically analyzed. Importantly, Anya wants to know if anyone in the audience had Okinawan pottery in its collections. If so, she wants to know! Please contact her if you have information on Okinawan pottery and/or specimens in your collections. Her information is in the AIC directory.