What factors contribute to the deterioration mechanisms for cedar bark? Peter McElhinney’s presentation on work completed as an Andrew W. Mellon fellow in object conservation at the National Museum of the American Indian in Washington D.C. addressed this question. His project was inspired by encountering labels on storage boxes for objects in the collection with the words “Inherently Fragile: Will Have Continued Loss.” Peter set out to better understand why cedar bark deteriorates so rapidly and dramatically.
Objects made from cedar bark come from Western Red Cedar trees that grow in the North West coast region of North America. Native groups in that region harvest and weave cedar bark to make baskets, hats, mats and other objects. Cedar trees can grow to between 65-70 m tall and 3-4 m in diameter. One of the unusual features of these trees is the way that the bark is made and the type of cells present on the exterior of the bark. Peter focused on four aspects of cedar bark that play a major role in the way it deteriorates: the disruption of the cells on the exterior bark, calcium oxalate crystals, dehydration of pectin, and phenols.
Peter demonstrated the changes to the bark’s cellular structure using diagrams and CT scans. Cedar bark, called phloem, is made up of sieve cells, parenchyma cells and fibers. Cross sections of bark examined with a Skyskan 1172 micro CT scanner from Micro Photonics Inc. enabled the differentiation of inner and outer phloem. The cells in inner phloem, the section of the bark closest to the tree, are orderly, more rectilinear, and less disrupted. As the cells are pushed towards the outside of the tree, they become outer phloem, and develop a more disordered, compressed, less rectilinear appearance. The fibers in outer phloem have stronger cell walls, whereas the parenchyma and sieve cells tend to be crushed or squished. These changes in the phloem relate directly to the shedding characteristic of objects made from cedar bark.
The CT scan also revealed the presence of a large bio-mineral crystal in the bark sample. These bio-minerals form as part of the normal function of cedar trees based on minerals absorbed from the soil. Scanning electron microscopy with energy dispersive spectroscopy identified small, shard-like crystals as calcium oxalate and the large particle as a silica aluminum crystal. The small shard-like crystals were most abundant in the cell walls in the middle and outer phloem. This corresponds with literature that cedar trees have 10-20 times as many calcium oxalate crystals as other trees. These crystals may cause cell wall abrasion during manipulation of the cedar bark, which could contribute to the bark’s rapid deterioration.
The dehydration of the pectin and phenols also affect the cells. Cedar bark used for objects loses moisture over time, which can cause the dehydration of the pectin in the bark. Dehydrated pectin may reduce the ability of cells to adhere together. Significantly higher numbers of phenols are present in the outer phloem than in the inner phloem. The phenols protect the bark from ultraviolet radiation damage. This characteristic could influence lighting requirements for objects made from cedar bark if we can determine whether they are made from inner or outer bark.
Conservation applications of these findings help to improve understanding of how cedar bark deteriorates. The cells in outer bark are already structurally compromised, which can contribute to the shedding associated with cedar bark objects. Calcium oxalate crystals can further damage cells during handling of the object. Dehydrated pectin reduces cell adhesion within the bark. Finally, phenols present in high quantities in the outer bark may project the material from damage due to Ultraviolet radiation. Overall, this talk applied complex information about cellular biology to develop a better understanding of cedar bark deterioration mechanisms. This information is essential for developing better preventive care handling procedures for these fragile objects. I’m looking forward to reading the post prints for this talk and studying the figures and images in more detail.
Month: June 2014
Project Manager/Staff Conservator, Clerk of Civil District Court for the Parish of Orleans
Project Manager/Staff Conservator Orleans Parish Clerk of Civil District Court
The Clerk of Civil District Court for the Parish of Orleans seeks a full or part-time Project Manager/Conservator to oversee and manage a grant-funded conservation project for oversized volumes of original documents.
| Duties: | Conductall aspects of book and paper conservation as primary resource in the organization. Work effectively and constructively both independently and as part of a team. If part time, must have flexible work patterns to meet organizational needs.Plan, manage and implement conservation treatments for archive collection including loose and bound documents. Implement high level written and photographic documentation as needed for projects. Maintain existing plan and protocol for project, manage resources, order materials. Develop and maintain efficient workflow patterns, gather, analyze and present information accurately for the purpose of recording, planning and reporting conservation treatments. Train and supervise staff of four or more full time conservation technicians as well as interns when applicable. Maintain a close working relationship with the archivist and management team. Uphold a high standard of written and verbal communications with staff and patrons on all levels. Produce written reports as needed by the archivist, management staff and outside granting agencies. Competency with Microsoft Office, Access, digital photography, and associated software. Serve as a member of the Disaster Response Team as needed. |
| Qualifications: | Degree in Conservation Studies. Bachelor’s degree in History, Art, Humanities, Library Science or related field and equivalency. MLS or MLIS or additional archival training is desirable.Experience Requirements: Demonstrated experience working with special collections material. Demonstrated communication experience working with a wide variety of staff and faculty. Preferred experience supervising book and paper conservation tasks. Preferred minimum of one-year previous experience, or equivalency, performing library book conservation within a research library or archive setting. Physical Requirements: Excellent hand-eye coordination. Able to work standing up for many hours. Able to operate light machinery (board shear, backing press, standing press). Able to lift and carry 30 pounds. Able to comply with archive and conservation guidelines on health and safety. |
This is a full time or part time contract position. Pay is commensurate with experience.
Applicants send resume with cover letter to:
Sally Reeves, Archivist, sreeves@orleanscdc.com
Conservation Technician, Office of the Clerk of Civil District Court for the Parish of Orleans
Conservation Technician Position
The Office of the Clerk of Civil District Court for the Parish of Orleans is seeking qualified individuals to perform general conservation treatment and perform condition surveys of archival collection materials. This is a technical position following well established national conservation guidelines to evaluate the condition of archival materials and perform repair and preservation techniques to stabilize materials.
Knowledge, Skills and Abilities
Candidate should have experience in book or paper conservation, experience using conservation tools, and knowledge of conservation equipment and handling techniques. Experience with digital photography is also desirable.
Candidate should be able to handle, humidify, flatten, and mend damaged and possibly moldy archival documents and bindings. Minor to advanced book repair will be assigned and performed as needed. Candidates should be able to create custom enclosures including phase boxes, “tuxedo boxes,” post bindings and additional unique housings as directed by supervisor. Batching skills are necessary.
Conservation technicians must be highly organized, self-motivated, and able to work under pressure. One must utilize excellent oral and written communication skills to interact with team members and to convey changes in scope of work that may affect multiple project deadlines. Applicants must support the mission to preserve archival materials for public use and be able to perform quality control of in-house repairs and contracted library binding. Technicians must have the ability to follow instructions and to establish and maintain positive working relationships with co-workers and the public.
Successful candidates have good time management skills, ability to multitask, ability to meet deadlines while organizing and prioritizing daily treatments in addition to compiling accurate statistics on work performed. Technicians need to work independently and consult supervisors to resolve problems, set protocol and perform work as needed. Candidates must have the ability to maintain and manage tools, equipment, and conservation supplies and to be flexible with changes in work location and tasks.
Training and Experience Requirements
High school diploma or equivalent needed, along with training in conservation or equivalent field. Two years additional education preferred. Must be 18 years of age and degrees must be from appropriately accredited institutions.
Physical requirement
The tasks demand the ability to work for long periods while standing, to lift and carry materials weighing up to 50 pounds and to perform repetitive activities. Applicants must have excellent manual dexterity, be able to push book carts between building floors and be able to work in an environment with dust.
Preferred Requirement: Experience working in a library or archive, awareness of archival terminology and functions and previous experience performing collection condition surveys and designing repairs is preferred.
The position is full time and salary is commensurate with experience. Applicants send resume with cover letter to: Sally Reeves, Archivist, (sreeves@orleanscdc.com).
42nd Annual Meeting – Interest Session, May 31, “Syllabus Sharing Session”. Chaired by Emily Williams.
This was a pretty informal session but it was attended by a lot of really enthusiastic people. When I arrived in the room shortly before the start time the discussion had already started. By the time Emily Williams arrived (one issue with this session was a lot of competing interests at the same time) only 5 minutes later, we were already well into it and she had her work cut out to herd the syllabus-sharing cats.
The initial premise of the meeting was for people either teaching or interested in teaching conservation to allied professions to get together and share their ideas for teaching. This arose from interest expressed at the last annual meeting. Emily Williams, who guided the session, explained that there wasn’t a big plan for it, they just wanted to provide a space for discussion and she wanted to distribute a short questionnaire to determine interests (see end of blog for the questionnaire questions; please send your answers to the questions listed to Emily Williams)
When I came in, the discussion centered on what kind of sharing was proposed. Some participants were unwilling to post their syllabi online for various reasons, although they’d be willing to share them with interested people via email. The group seemed pretty evenly split on this topic but even without general consensus on that topic there were a lot of interesting ideas and useful resources discussed.
One suggestion (sorry, everyone, I was having a hard enough time jotting down the ideas that were coming fast and furious and didn’t always note who said what) was a list of who was teaching what, where, and whether to undergrad or grad students, so that we could see who was teaching something akin to our interests and reach out to them. Another participant was interested in adding information on class size and whether the instruction was compensated. At this point, Emily came in and let us know that AIC’s e-editor Rachael Perkins Arenstein and she had just discussed setting up a Wiki page that could host just this sort of info, so that was great. This ‘Teaching to Allied Professionals’ wiki page would be akin to the existing Exhibiting Conservation .
Several participants offered useful resources; these came up at various points in the discussion but I’m going to lump them together here:
- Chemistry in Art is the first web-based community launched by the NSF-sponsored Chemistry Collaborations, Workshops and Community of Scholars program (cCWCS) . The CiA community is primarily designed for college-level instructors to network and to collaborate; and to access, share and develop curriculum materials.
- GCI has a lot of good teaching resources. “The GCI is pleased to make available didactic resources that have been produced and used in the Institute’s courses, workshops and field training. These resources include outlines of teaching sessions, bibliographies, exercises, case studies, and technical notes that can be downloaded and used by conservation educators and students in the classroom and by professionals for informal, personal learning according to the terms described below.” GCI puts everything up under a Creative Commons License. Kathleen Dardes mentioned that she was particularly interested in getting feedback on this resource.
- NEDCC also has resources available freely.
- UCL has a very detailed online syllabus for their Conservation for Archaeologists course:
- Renee Stein and Katherine Etre at the Carlos Museum have worked with science teachers to develop a resource for high school science labs based on art conservation. Carlos.emory.edu/science-art-conservation
There was some discussion of how to write a syllabus; Emily put forward the view that we should think of a syllabus as a contract between the student and instructor. Some felt that this might lead to a voluminous syllabus and suggested adding a generic paragraph that everything is subject to change. There was general agreement that it was important to communicate fully with students to understand their expectations and to explain your expectations. List outcomes and rubrics (this was unfamiliar use of rubric for me so I turned to Wikipedia for explication: “In education terminology, scoring rubric means “a standard of performance for a defined population”.” Live and learn). The students need to understand that taking one course will not transform them into conservators. Instructors in a university setting may need to follow institutional guidelines for syllabus-writing but also may be able to get help from their Centers for Learning Excellence.
At our request Emily explicated what the relationship was between ETC (the AIC Education and Training Committee of which she’s also a member) and this syllabus sharing group. In short, the ETC is tasked with overseeing AIC’s education initiatives (mostly directed at conservator education) whereas our adhoc group was directed at conservation education for allied professionals.
At this point, we went around the room and introduced ourselves and talked about our specific interest in the topic. It was fascinating to learn how many different ‘allied professionals’ were interested in or could benefit by an academic introduction to conservation basics: art students (who could learn how to make their artworks more permanent or definitely ephemeral); museum studies programs; collections managers; archaeology and anthropology students; art history students; library scientists and archivists; programs for chemistry, materials science or engineering students, and others I’ve probably left out. One participant was especially interested in identifying and accessing online resources that could be used by students in the Developing World.
Emily polled the room to see if there was interest in a session for the next Annual Meeting on how to teach. If you weren’t there but would are interested, please fill out the extremely short survey at the end of this post.
I have not yet taught a full semester University level course, just classes in other courses and workshops in host countries. But I hope to do so in the next year or so as our Museum starts an exciting new initiative for teaching archaeological science to undergraduates. Having long felt that most American archaeology and anthropology students need to understand more about conservation, I’m pretty passionate about this topic and it was great to be in a room with others who share that passion.
SURVEY DISTRIBUTED AT SESSION:
We are hoping to organize a formal workshop on teaching for the Miami AIC meeting. To help us plan this and future events please answer the following questions and return this form to either Emily Williams (ewilliams@cwf.org) or Suzanne Davis (davissl@umich.edu)
- What resources would you most like to see AIC develop to aid you in your teaching. These resources might include items for the soon to launch “Teaching to Allied Professionals” wiki page, continued education courses for conservators engaged in courses, course materials for use in the classroom or other items. Please write down anything you think might be useful.
- Is there a particular challenge that you feel you or other conservators face in teaching Allied Professionals that you particularly wish to see addressed through workshops or the wiki page.
- Have you developed course materials or other teaching aids that you are willing to share with other conservators? If so, what types and how may we contact you?
42nd Annual Meeting – Workshop, May 28, Respirator Fit Test Lecture and Respirator Fit Testing, May 29 by appointment, AIC Health and Safety Committee
In the past year have you:
- Grown a beard to emulate your conservation idol Steve Koob?
- Participated in a juice cleanse which inspired a new pattern of healthy eating and daily lunchtime walks?
- Had a little work done ?
- Contracted Hepatitis B while doing archaeological site conservation in an exotic foreign location? (I sure hope not!)
If you answered yes to any of these questions then you are a candidate for a respirator fit test even you don’t work in a place where an annual test is required. Facial hair, weight loss or gain of 20lbs or more and any other changes in the shape of your face may mean that the respirator you have been wearing is no longer tight-fitting. Serious illness may compromise your respiratory and/or other systems making respirator use dangerous.
I trust that those reading this are already aware of the importance of protecting ourselves from the potentially harmful chemical compounds (vapors and particulates) and other irritants (such as mold) that we may be exposed to in the course of our work. Depending on the risk, such protection might be afforded in a variety of ways such as via the use of laboratory fume hood, appropriate room ventilation systems including workstation elephant trunk style air outlets, and/or personal protective equipment (PPE) such as a dust mask or respirator.
If you don’t work in a museum or other institution with a designated health and safety officer following OSHA required guidelines, you might be unclear about what kind of mask is required for a particular contaminant and even what “fit testing” means. Personally, never having been “fit tested” before, I will admit that for years I wasn’t even 100% clear whether it meant “are you fit (in proper health) to wear a respirator?” or “does the respirator fit?” Of course it means both! These days all you need do is consult the very informative AIC Health and Safety Committee Wiki to get your fill of information about respirators and so much more
http://www.conservation-wiki.com/wiki/Health_%26_Safety#Personal_Protective_Equipment_.28PPE.29
As a conservator in private practice, I have no employer checking up on whether or not I am protecting myself. Several years ago I purchased a respirator, which seemed to fit well. While wearing it with the correct cartridges for the organic solvents I was working with, I figured “If I can’t smell the vapors it must be fine.” But I was never really sure that it fit and it is important to follow guidelines about the life of your cartridges to be sure you are getting adequate protection.
When I signed up for the respirator fit test, the AIC Health and Safety committee sent me the six-page OSHA Medical Evaluation Form (mostly check boxes with yes or no) to fill out and have signed by my doctor prior to fit testing. Keep this in mind if you plan to participate in fit testing at AIC next year – you must plan ahead and have this signed paperwork in hand or you will not be allowed to be tested! This form is available for download on the wiki.
The respirator fit testing consists of two steps, both of which fulfill the annual requirements mandated by OSHA. First, a brief Powerpoint, given by James R. Smith, Safety Coordinator at the Smithsonian Museum of Natural History, covered topics from the requirements of the Respiratory Protection Program (29CFR 1910.134) to hazards requiring a respirator, how to choose the correct respirator, care and maintenance, donning and doffing and training requirements for employers. The lecture was accompanied by handouts prepared by AIC Health and Safety and we were given a 10 question true or false quiz at the end.
I had scheduled my fit testing appointment prior to traveling to San Francisco. AIC Health and Safety asked participants to choose their top three time slots on the given date in order of preference. When I arrived, I noticed that there were still a couple of time slots available. I would highly recommend pre-registration for fit testing at AIC if you plan to do it next year because then you are guaranteed a spot.
The fit testing itself was quite simple. After donning my mask, James handed me a card with a poem to read while moving my head up and down, side to side and in a circular motion.
While I read this rainbow poem, he followed me with a little pen like device emitting an irritant smoke. I believe that the finale required bending at the waist. The test was brief and painless and I was relieved to hear that I had passed – particularly since I had already used the respirator on numerous projects. Once the test was over, James offered to prove to me that the respirator worked by allowing me to experience the irritant sans respirator. I declined saying that I trusted the test. However, he said that some people like to have proof and offered again. Somehow I took the bait and learned first hand that indeed, the gas is an irritant and my respirator is working properly.
Thank you to James, Kathryn A Makos, MPH, CIH (Industrial Hygienist (Ret.) Smithsonian Institution) and the rest of the AIC Health and Safety Committee for offering this service at the annual meeting.
42nd Annual Meeting – Electronic Media Session, May 31st, “Establishing Time Based Media Conservation at the National Galleries of Scotland; Creating More in Times of Less" presented by Kirsten Dunne, paper conservator at the Scottish National Gallery of Modern Art in Edinburgh, Scotland
I really enjoyed Kirsten’s Dunne’s talk because she addressed a challenge that all conservators face regardless of their specialty. That is developing economically viable and sustainable solutions for collections management which are flexible enough to anticipate and adapt to a future that includes an increasing amount of time-based media and other conceptual or intangible works of art. Ms. Dunne, a trained paper conservator, has nobly volunteered to take on this challenge in addition to her regular duties because, as in many institutions facing cuts and austerity measures, there is no budget for a full time, time-based media conservator at the GMA. So, how is she faring and what advice does she have for the rest of us?
The Scottish National Gallery of Modern Art currently has around 20 time-based media works. The first challenge that Ms. Dunne faced was to locate each one and manipulate Mimsey, the GMA’s CMS, to make sure that each was properly characterized and documented. She stressed the importance of an artist questionnaire or interview at the time that each piece is acquired. This is the best way to insure that the information gathered is accurate and also an appropriate time to make a record of any contemporary technology that may be required to display the work (such as a VHS or laser disk player, projectors, or sound equipment). This information is especially important if your institution has purchased a master copy for loan and repeat display, as opposed to an exhibition copy that must be disposed of after a single showing. The legal implications of this had never occurred to me, nor the fact that proper and complete erasure of an artwork can be an issue. This was part of the underlying theme of Ms. Dunne’s talk which cast the conservator as ethicist. It became her job to answer legal and moral questions about the work such as ‘How many copies can be displayed simultaneously?’ and “Who should have access to the digital files?” She said that she was compelled to question who she was as a professional and that the exercise ultimately reinforced her confidence in her own knowledge base and the ethical principles which she cultivated during her training.
Ms. Dunne went on to say that one excellent source of guidance was “Matters in Media Art,” a collaboration between MoMA, SFMoMA, the New Art Trust (NAT), and Tate, which has an established time-based media lab. The project, which can be found here, is “designed to provide guidelines for care of time-based media works of art.” The templates provided her with a list of questions which assissted her research and shaped her approach to documentation. Gradually, she said that she began to “close the knowledge gap,” and to implement some quick organizational strategies. These included:
1. Physically consolidating time-based media works in storage and documenting their new locations
2. Entering new information fields and consistent keywords in the museum’s CMS in order to describe and track pieces and
3. Drafting a preservation management plan for electronic and time-based media, which included an “Equipment Asset Register” to track on site audio visual equipment and which could be programed to send an alert when that equipment was in danger of expiring
Ms. Dunne offered some excellent advise for any conservator who is faced with unfamiliar materials and formats, namely:
1. Trust Your Instincts because the broader principles of conservation will hold true and
2. Embrace the Chaos! because the best way to learn is by doing.
She also talked about the value of involving your colleagues such as curators, registrars, and IT staff. Sometimes it can be a challenge just to get others to recognize that a conservator should be involved from the beginning regarding decisions about display and storage, even if there is nothing currently “wrong” with the piece. Often, a general lack of experience with new media pieces leads to fear, and consequently, neglect. She explained that she was able to barter her time and expertise with time-based media conservators at other institutions whose experience proved to be invaluable. In fact, interinstitutional sharing can extend to those ancillary components like betamax machines or tape decks, and she suggested partnering with other institutions to create a repository of such devices. This approach can cultivate good will and also form a visible, public partnership.
In summary, Ms. Dunne found that while establishing her museum’s nascent draft of core guidelines for conserving and exhibiting time-based media was challenging, it was a rewarding experience. She reported that she made allies in the field, added to personal and institutional knowledge of the collection, and came to regard herself as “a conservator” rather than “a paper conservator” who was prepared for the challenges posed by an evolving artistic landscape. Her concluding words to institutions were these: “ If there is someone on your staff who wants to take on a similar project or responsibility for your time-based media collection, give them that freedom! You will benefit tremendously.” And to educators and conservation professionals: “Continue to act as mentors. I’ve been lucky to have the support of those in the field.”
42nd Annual Meeting, RATS session, May 29th, “Free fatty acid profiles in water sensitive oil paints: a comparison of modern and 15th century oil paints,” presented by Joy Mazurek, Assistant Scientist, Getty Conservation Institute.
A standard method in many conservation science labs is the use of Meth-Prep II (a methanolic solution of trifluoromethylphenyl trimethyl ammonium hydroxide) for the transesterification of triglycerides to methyl esters and esterification of free fatty acids (FAs). However, this method gives you the total fatty acid content of the sample, including free fatty acids, their oxidation products, fatty acids bound in metal soaps, and intact triglycerides. If you want to assess the extent of hydrolysis of an oil paint film, which might be related to water sensitivity, you need to use another method. What Joy has chosen to do is to modify the Meth-Prep II solution to prevent transesterification. She takes 400 μL of Meth-Prep II, evaporates it at 50 oC under nitrogen to remove the methanol, rinses it with toluene, and then adds 500 μL of toluene and 100 μL of t-butanol. T-butanol does not permit transesterification, but the methylation of free alcohol groups can still occur. So a sample can be analyzed with this modified solution- only the free fatty acids and fatty acids in metal soaps (non-glycerides or NG) will be methylated, and thus only they will quantified by GC-MS. Then the same sample can be re-treated with the normal Meth-Prep II solution to determine the fatty acids in triglycerides.
As with any quantitative GC-MS method there are potential issues. The sample needs to be well homogenized to ensure extraction and reaction. The efficacy in methylation of fatty acids soaps is not known, and so those species may not react fully and be underrepresented in the chromatograms. She also sees partial evaporation of her internal reference when the sample is retreated with unmodified Meth-Prep II and so that must be accounted for.
With all of these caveats in mind, they began to look at reference paints, including Bellini tube paints and handmade paints in cold-pressed linseed oil. For the new handmade paints the fatty acid profiles of the NG and the total FAs look similar. But pigments do make a difference- for yellow ochre and red iron oxide paints, the NG accounted for 50-57% of the total FAs, but for malachite and lead white paints the NG fraction was much lower, approximately 12%. This might be due to the formation of metal soaps and poor extraction of fatty acids from those complexes.
For water sensitive Winsor and Newton oils she found 17-37% NGs, although the high levels of palmitate present in cadmium paints may indicate the addition of palmitate soaps. However, there was nothing obvious about the fatty acid profiles that seemed to relate to the water sensitivity. Likewise, a water sensitive cadmium paint in a 1961 Jack Youngerman painting, while also having elevated palmitate levels suggesting palmitate soap addition, had nothing else unusual about the binder. To address this issue cadmium yellow and a chrome yellow paint were mixed with linseed oil, applied onto canvas and glass and artificially aged. The resulting cadmium yellow paint film was very water sensitive, while the chrome yellow film was not. However, there was no major difference between the NG ratios of the two films, and so something else must be rendering the paint sensitive. Furthermore, that sensitivity is not related to the palmitate soaps found in the commercial paints. So there’s more work to be done to determine what is going on, but in the meantime beware cadmium paints!
She had the opportunity to analyze a sample from MOMA’s Water Lilies by Monet, which has a very water sensitive surface. The total FA content of the samples were very low, indicating a very medium poor paint, consistent with Monet’s working method of removing media from his paints. The NG content depended strongly on the sample location and pigments present. The pink-orange paint contained no stearate or palmitate, while other samples contained very high palmitate in the NG fraction. Again, the origin of these differences cannot be explained at this time- but might be due to soap formation and incomplete methylation.
Additional objects tested with this methodology included a variety of Italian paintings ranging from 1595-1758 in date, a Byzantine painting, a Fayum portrait, and a Jackson Pollock painting. The Italian paintings had higher NG fractions than was observed for the tube paints and modern paintings, 22-66% of the total fatty acids, but the NG fraction did not correlate with the age of the material- so extent of hydrolysis cannot be used to determine the age of an object. One possible explanation for this is that paintings this old have likely been cleaned several times and this may have impacted the amount of free fatty acids. The Byzantine painting had a higher NG content of 40-90% and the high palmitate and stearate amounts suggested the formation of metal soaps. Joy found that the modified Meth-Prep method simplified the analysis of beeswax and resulted in less overlapped and confusing chromatograms. In 19th century beeswax she found palmitate and stearate, but in a sample of unpigmented wax from a Roman tomb, she detected neither of those species, implying that they had all evaporated with time. However, in the pigmented Fayum portrait both species were seen, which might be due to the formation of metal soaps, which would help preserve those species, or to the modification of the wax- a contentious subject in the art history field. The white sample from the Pollock painting contained no fatty acids at all, so they evaporated the Meth-Prep solution and reanalyzed it using a method developed for proteins and determined that it was actually a casein paint.
So this seems to be a promising method, and one that could fit easily into a laboratories work flow. Obviously there is more work to be done- particularly on determining efficacy of extraction of fatty acids from soaps and trying to determine how certain pigments create water sensitive films without altering the fatty acid ratios…
42nd Annual Meeting, Objects and RATS joint session, May 30th, “Animation Cels: Conservation and Storage Issues,” presented by Kristen McCormick, Manager of Art Collections and Exhibitions, Walt Disney Animation Research Library.
“Darling, forever is a long, long time, and time has a way of changing things.”
—Big Mama, The Fox and the Hound.
Kristen chose that quote to begin her talk, and indeed it is true of all objects in cultural heritage institutions. Her particular institution, the Walt Disney Animation Research Library is home to over 60 million objects, including animation drawings, pencil story sketches, watercolors, maquettes, and animation cels, the latter of which make up approximately 10% of the collection. Animation cells are transparent sheets of material, usually celluloid (nitrocellulose), cellulose acetate, or polyester that have been inked on one side, and then painted with gum based media on the other. These materials, particularly cellulose nitrate and cellulose acetate, are highly prone to degradation, so the library partnered with the Getty Conservation Institute to investigate the material nature of the cels and determine if the environmental conditions in the library (62-65 oF, 50% RH) and the microclimate packaging used were sufficient to protect these objects.
Phase one of the project involved investigation of the material nature of the animation cels, addressing the questions: what is the base polymer of the cel, what plasticizers are present and in what quantity? They initially used a portable FTIR and non-destructively analyzed 200 cells dating from 1937-2003, and then chose 80 of those items to do more in-depth, microdestructive GC-MS analysis on. In their initial survey they found cellulose nitrate, cellulose diacetate, cellulose triacetate, and polyester as the base support material. Surprisingly, the material used for a single production would not necessarily be the same; it seemed that the artists used whatever was at hand. Due to the limits of the talk time, Kristen chose to focus on the acetate films for the rest of her talk.
The cellulose acetate cels were found to contain 11 different plasticizers, 6 different types in the diacetate and 5 in the triacetate. These included triphenyl phosphate and a variety of phthalates including dimethyl phthalate (DMP) and bis(2-methoxyethyl) phthalate (DMEP). The plasticizers accounted for 12-19% by weight of the diacetate films and 8-14% by weight of the triacetate films. The diacetate films had an acetyl content of 35-41%, while that of the triacetate films was 43-45%. They are not sure if the range is due to partial hydrolysis or variability in manufacturing. There was no correlation between acetyl content and production year. However, it did appear as if the older films might be a bit more yellow, but more work needs to be done to determine if this is a viable observation.
Phase two was assessing the environmental conditions, or as Kristen said quoting Mufasa from The Lion King, “Everything you see exists together in a delicate balance.” Since this portion was focusing on cellulose acetate cels, Kristen referenced Image Permanence Institute guide for the storage of acetate film (https://www.imagepermanenceinstitute.org/webfm_send/299) and pointed out that the library’s storage conditions were outside of the optimal range recommended by the IPI (50 oF or lower, 20-50% RH). However, the cels are composite materials and it is unknown how the gum based paints would react to lower temperatures and what kind of mechanical stresses might be induced by those conditions, so they feel that the chosen conditions are a good compromise. However, belief isn’t the same thing as actual data, so they performed a survey using AD strips, looking at four vaults and 8 different locations. The strips were assessed after 8 and 96 hours and only one location, next to the Bambi collection, was off-gassing acid. They are planning on investigating that collection further to zero in on the problem.
The library also stores and exhibits the cels in passé-partout packages that include a window mat, the cel (usually hinged with Japanese paper and methyl cellulose), matboard, and a sheet of Artsorb conditioned to 50% RH. They include a RH strip to be able to easily determine if the Artsorb is working. This was supposed to be best working practice but after an exhibition of cels at the Grand Palais, they noticed microcracks and paint delamination and became worried that the package was concentrating off-gassed materials and accelerating the decay of the cels. To try and determine what was happening they extracted gas from a sealed package and analyzed the entrapped air by GC-MS. No acetate (at least above 800 ppb) was detected, suggesting that hydrolysis of the cellulose acetate was not occurring. AD strips were also inserted into packages and no color change noted. Thus they decided that neither the package, nor the exhibition conditions was causing hydrolysis of the acetate groups. They did find adsorbed camphor in a package containing cellulose nitrate, so scavenging of plasticizers might be an issue. Thus, they think that their environmental conditions are generally good and that the passé-partout packages are not the issue. They are not sure what caused the observed deterioration; whether it was mechanical damage caused by temperature changes, vibration during shipping, etc. and are continuing to look into this. They are also planning to begin looking at the ink and paints to better understand the complete nature of the cels.
For more information on this project see the Getty Newsletter:
http://www.getty.edu/conservation/publications_resources/newsletters/29_1/animation.html
42nd Annual Meeting, Textiles Session, May 29th: A Case Study Using Multi-band and Hyperspectral Imaging for the Identification and Characterization of Materials on Archaeological Andean Painted Textiles by Rebecca Summerour and E. Keats Webb
The paper began by acknowledging a third author who was inadvertently left off the program and abstract booklet, but will appear as a third author in the TSG Postprints. The paper was presented by E. Keats Webb, the digital imaging specialist for the Conservation Institute at the Smithsonian. She showed how by combining a lower resolution spectral camera (Surface Optics Corp SOC710) with a modified DSLR with bandpass filters, the resulting images could be used to identify certain pigments on a painted textile. The project began with four textiles being described as plain weave with color (a limited color palette of browns and blue/blacks) delivered in a paste form without an organic binder, the color remaining on one side – this is important, keep this in the back of your thoughts as you continue, dear Reader!
I live in Silicon Valley, but I am not tech savvy. I am also several years out of school and realize that I my not have the vocabulary to give a precise recall of the methods and analysis described. Having said that, I feel I did learn about a (relatively) low cost technique that would be helpful in characterizing pigments on textiles. Essentially, the technique required several images to be taken at various bandwidths along the visible to near infra-red spectrum. Knowing the reflectance spectra for a given pigment allows the researcher to target the images for analysis. The targeted images are overlayed to get the difference which results in areas that appear to fluoresce for a positive identification.
It was found that indigo was readily identified, whether it was used alone or as a component of other colors. Reds and browns proved a bit more problematic. The success of this technique seems to have been that there was a small color palette, as well as the textiles in question were of known provenance, so they already had an idea of the pigments to look for. Also, the pigments were on one side and in good quantity. They did not achieve good results with dyes or small samples due to background noise interference. Though it was brought up in the question/answer portion that HPLC gives definitive “fingerprint” spectra for positive identification, the imaging technique presented does not require sample-taking (important to the National Museum of the American Indian) as well as allows for the entire textile to be mapped, keeping the pigment identification within context.
I could see this technique as a very useful first step in pigment identification or potentially in identifying areas of restoration and the pigments used. I look forward to reading the paper in the Postprints.