In this presentation, I was looking forward to learning about the approaches that are taken in the preservation and conservation of modern built heritage.
Lacey Bubnash (Architectural Conservator at Architectural Resources Group) and Katie Horak (Senior Associate at Architectural Resources Group and Adjunct Lecturer at the School of Architecture, University of Southern California) shared their experience of preservation planning for The Village Green, also known as the Baldwin Hills Village, in Los Angeles.
Built in 1941-1942, the Village Green is a modern housing complex that includes residential buildings (today occupied as condos) with garages, community structures, such as a clubhouse and maintenance building, and large open spaces. The complex was designed with the idea of providing affordable housing for the pre-World War II community. On this account, inexpensive and mass-produced materials were used to construct the complex.
In their presentation, Lacey spoke about the site documentation that she and Katie prepared and reviewed during this phase, including the Historic Structure Report and Cultural Landscape Report respectively. These reports identify challenges for the site’s preservation and conservation, such as the presence of mid-century modern materials, and include recommendations for preservation and conservation treatments.
Lacey also presented about the application that she and Katie submitted for the Village Green’s inclusion in the Mills Act Property Tax Abatement Program. This Program is a financial incentive for historic preservation in California. It binds the participating city and the property owner in a contract that sees the reduction in property taxes in return for the property owner’s restoration and maintenance of the property. Their application was successful in obtaining a Mills Act designation for the Village Green.
I found this presentation to be a very interesting glimpse into the planning and preparations for the preservation and conservation of built heritage. I enjoyed learning about the process involved in such a large and multifaceted project – encompassing both built structures and designed landscapes – that bears the additional challenges of dealing with modern design concepts and materials.
Category: Objects Conservation
42nd Annual Meeting, Objects Session, May 31, Pine Pitch: New Treatment Protocols for a Brittle and Crumbly Conservation Problem by Nancy Odegaard, et al.
In this paper presented at Saturday’s Objects Session, Nancy Odegaard, Marilen Pool and Christina Bisulca described a new treatment protocol they established, along with their colleagues Brunella Santarelli, Madeleine Neiman, and Gina Watkinson, for treating baskets with deteriorated, pine pitch coatings. The treatment protocol was devised after conducting a survey of the basket collection at Arizona State Museum, where the majority of the pitch-coated ethnographic baskets (70 out of about 100) had unstable, blanched, cracked and brittle surfaces. The baskets required treatment so that they could be moved to a new location.
The majority of the baskets were Apache and were made using a twining or coiling technique. The pine pitch, obtained from the piñon pine would have been applied to the surface of the baskets as a waterproofing measure. Two colors of pitch were observed on the exterior of the baskets, each with different condition issues. Some baskets were covered with a red pitch that appeared translucent. The other baskets were covered with a dark brown to black, opaque pitch. Both colors of pitch had suffered degradation due to factors such as UV, temperature and pollutants, however the red pitch appeared more unstable and had a formed a series of fine cracks. The darker pitch had deeper cracks.
Because the baskets had to be moved, a treatment protocol was established to stabilize the surfaces so the baskets could be safely transported to a new storage area. Previous treatments for deteriorated pitch had included consolidation with solvents or the use of heat (using a butane torch!) to reintegrate the cracked, crumbly surface. The ASM team was looking for another treatment option, and one that took into consideration the vast numbers of objects that required treatment. Borrowing from methods used to clean aged varnish in the field of paintings conservation, the conservators decided to reactivate the pitch using a solvent to stabilize the flaking material and reattach the crumbly surfaces.
Prior to any treatment, the conservators wanted to get a cultural perspective on the treatment since they did not want to add material, alter the pitch or appearance of the basket and wanted to make sure the objected retain their cultural integrity and significance. Nancy consulted with a Navajo weaver who said that pitch baskets should always look shiny and therefore reactivating the pitch, and the subsequent shiny appearance the material would take, was acceptable.
Treatment
Because of the success in the use of ethanol in cleaning aged, pine-based varnish from paintings, that was the solvent chosen for the reactivation of the pine pitch on the ethnographic baskets.
- The first stage of the treatment was to place the baskets (many supported by foam rings or, if they fit, by large glass beakers) in an ethanol solvent chamber for 24 hours. This would condition the surface and prepare it for further treatment.
- The baskets were then removed from the solvent chamber and areas of the surface sprayed with ethanol using a Dahlia sprayer for a more direct application of the solvent.
- Brushes, foam swabs wrapped in PTFE (Teflon) tape and Kim Wipes (lint-free wipes) soaked in ethanol were then used to relocate any loose flakes.
- After one side was treated, the pitch was left to air dry for a few hours, then the basket was turned and the other side sprayed with ethanol and flakes reattached.
- When the entire pitch surface had been treated, the basket was left to air dry for about 24 hours or until the pitch no longer felt tacky.
During treatment the conservators noticed that the transparent red pitch reacted faster to the ethanol. The darker pitch was less soluble and more pressure was needed to re-adhere fragments. They also noticed that for areas with damaged basketry elements, the reactivated pitch served to reinforce those areas of the plant fiber so that no further stabilization of those woven elements were required.
Analytical Investigations
In addition to the treatment, instrumental analysis was conducted to characterize the two types of pitch and determine if there were any changes in the pitch before and after treatment. The analysis was conducted using Fourier Transform Infrared Spectroscopy (FTIR) and optical microscopy.
The first investigations looked at the two types of pitch and whether there were any changes observed before and after treatment. Analysis showed that there were no differences before and after treatment and therefore reactivation and exposure to ethanol did not alter the material chemically. There were differences, however, noted between the red and dark pine pitch. The transparent red pitch had a low aromatic component as opposed to the dark brown-black material, which had a high aromatic hydrocarbon content.
A series of experiments were then conducted in order to figure out what accounts for these differences and it turns out it has to due with how clean the pine pitch is and at what temperature it was initially heated to during application. Using optical microscopy, the dark pitch seemed to contain woody materials and had inclusions of bark. Could this be the explanation for the differences in the aromatic content?
Samples of resin from piñon pines in the Navajo area were collected and heated to different temperatures and then examined using microscopy as well as FTIR. It turns out that if the pitch is clean and does not contain any woody components, there are little to no aromatics. However, when bark is present in the pitch, the aromatic content is similar to that seen on the pitch coating the ethnographic baskets. The heating temperature also plays a role not only in the color, and a temperature of 180° C produces pitch similar to that seen on the ASM baskets.
This was a really informative talk describing a new approach to not only the treatment of crumbly pine pitch, but also a protocol for treating large numbers of unstable baskets. The talk was of particular interest to me because some close colleagues and I have often encountered similar types of condition issues with different resinous materials on archaeological objects (for example bitumen coatings on ceramics, bitumen or pitch on baskets, natural resins on Egyptian funerary objects and mummies) and have often discussed the need for approaches to the stabilization of these materials other than consolidation using synthetic resins. The literature is a bit lacking in terms of the treatment of these types of materials and it’s wonderful that Nancy and her team at ASM are adding to this body of information by sharing their treatment methods and findings (and hopefully publishing them in the OSG Postprints or another publication!).
The next stage of the pine pitch/basketry project will be to work on the archaeological basketry collection and I looked forward to hearing about their approaches to the stabilization of pitch on those artifacts.
42nd Annual Meeting- OSG, May 31, "Restoration by Other Means: CT scanning and 3D Computer Modeling for the Re-Restoration of a Previously Restored Skull from the Magdalenian Era by J.P. Brown and Robert D. Martin"
After collaborating with JP at the Field Museum on rendering CT scans a few years ago and seeing his article about this work in the spring MRCG newsletter, I was excited to see some images about this in person. JP has been working with CT scanners since 2006 starting out by taking advantage of the kindness of local hospitals and more recently renting a portable unit that came to museum on a truck.
As many of us know, CT scanners can look inside objects non-destructively and provide accurate images with 3D geometric accuracy. JP started the talk be reviewing some of the physics of getting a CT scan done, the benefits, and limitations. Here’s a run-down:
1. The scanner has a donut shaped gantry consisting of a steel ring containing the X-ray tube and curved detector on the opposite side, so your object has to fit within the imaging area inside the steel ring.
2. On each revolution you get lots of images scanned within 30 seconds to 5 min- this is very fast.
3. The biggest logistical challenge is moving objects to and from the hospital safely.
4. During the scanning you immediately get slices, which are cross-section images from three different directions. Volumetric rendering is done from the slices and there is free software for this.
5. Apparently it is relatively easy to do segmentation, segment out regions of interest, and extract wire frame models, just time consuming. From there you can get images of the surface and texture and can even print the models. It is relatively easy to go from slice to wireframe, but harder to achieve a manufacturing mesh to produce a 3D print, which can be expensive in comparison to traditional molding and casting.
6. PROs of scanning and printing: there is no contact with the object, complex geometry is not a problem, the scans and volumetric rendering are dimensionally accurate, you can print in lots of materials; prints can be scaled to make large things handleable or small things more robust for handling or increase visibility; subtractive manufacture, in which you can use a computerized milling machine to cut out a positive or negative, is also a possibility.
7. CONs of scanning and printing: printing is slow, the build volume is limited, a non-traditional skill set is required of conservators to produce the final product, and only a few materials age well. The best material is sintered nylon, extruded polyester may also be safe, but it doesn’t take paint well; it is hard to get the industry to think about permanence.
The object at the center of this project was a Magdalenian skull. The skeleton itself is of considerable importance, because it is the only magdalenian era skeleton of almost completion. A little history: it was excavated, quite professionally, in 1911 when they lowered the floor of the site. Unfortunately the burial was discovered when someone hit the skull with a pickax. Needless to say, the skull did not come out in one piece. In 1915 the full skeleton was removed in two blocks. My notes are a little fuzzy here, but basically at some point between the excavation the skull was restored and then went from being 2 pieces to 6 pieces, as it is documented in a 1932 publication by von Bonen. It appears that at that point the skull was also skin coated with plaster. Thankfully (?) those repairs have held up. Great, so why, did they need to scan and reconstruct the skull? Well according to Dr. Robert Martin, JP’s colleague at the Field Museum, the skull doesn’t look anatomically correct. Apparently during the time period when it was put together there was an interest in race and the skull fragments could have been lined up incorrectly accentuating cultural assumptions.
A previous x-ray showed that two fragments in the forehead are secured with a metal pin. In 2012, when the mobile CT scanner came to the museum, they were all geared up to start with the Magdalenian skull. Unfortunately there was not much difference in attenuation between bone and plaster making it tricky to define between the two materials in the scans. JP consulted a cranial reconstruction group and asked them to pretend this was a pediatric car crash victim with a cranial injury; they asked, why aren’t you using the mimics software package?
JP and his team also imaged the skull with a micro CT scan that has a 0.1 mm resolution versus the normal modern setting of 0.3 mm. They had previously identified 36 fragments of bone from the previous scan. It was hard to tell if some of those separations were just cracks or actual breaks between fragments. The hope was that the micro CT scanner could better define these areas. The micro CT scanner works opposite to the industrial/medical scanner. As you can see in the image to the left, the tube and detector are fixed, while the sample is rotated. Other differences are that it is slower, one scan takes 30-90 minutes and because of scanner geometry the skull had to be imaged in two scans . Because of this, JP used the previous scan to mill out a contoured support to hold the skull in the exact position. JP noted that digitally filling in the holes of the skull to create the support was the most time consuming part of that process and suggests using different radio-opaque marker dots to identify left and right for orientation during the later stitching process. With the new scans at least three separations were identified as cracks vs. breaks.
Now for the virtual reconstruction… the biggest obstacle in this stage was how to achieve something more anatomically correct using the virtual fragments when they have no boundaries. The fragments don’t push back in the computer- and the fragments can easily move into each other. With the software JP used mostly the translation and rotation functions and the free animation software Blender (which has a high learning curve and took several days to get accustomed to) to create hierarchical parent child relationships between the fragments as he joined them together. Just like putting a vessel together, right? In the virtual world at least there is no worry about lockout. They had a 3D printed of the final skull reconstruction and had an artist do facial reconstruction, which JP thinks always look related to Jean Luc Picard… So how successful was this? From a conservation perspective- awesome, it’s fully reversible! Scientifically though, it’s decent, well documented and scientifically justifiable- However, someone else could go through the same process and come up with a different reconstruction because of their reliance on left right symmetry for this reconstruction…
So what did I take away from this talk? This was a very cool project and if I have a question about CT scanning and 3D renderings, I will call JP! The scans can be extremely informational and there seems to be a lot of potential in their use for mount-making, crates, and storage, and possibly virtual reconstructions. Hopefully at some point in the future the software will become more intuitive and easier to use so that more of these types of projects can be done.
42nd Annual Meeting – Architecture + Objects Joint Session, 29 May, 2014, “Conservation Realities and Challenges: from Auto Regulation to Imposition at Archaeological and Historical Sites in Colombia” by Maria Paula Alvarez
I was drawn to this presentation on account of my background in archaeology. Although I have never had the chance to visit Colombia, I was very interested to hear about the challenges, that Colombian conservators, archaeologists, and other allied professionals encounter in their efforts to preserve their country’s archaeological and historical sites.
Maria Paula Alvarez, Director at the Corporacion Proyecto Patrimonio, presented a number of interesting case studies to illustrate the types of conservation and preservation problems that she and her colleagues face and work on solving. Her examples included assessments, research, testing, and treatments at
1) archaeological sites, such as:
- The Archaeological Site of Fuente de Lavapatas, where the conservation issue was stone deterioration. Extensive studies – including the evaluation of the environmental conditions at the site and the geological and physical properties of the affected stone – were conducted to determine the causes of deterioration. As well, testing of treatment materials – including biocides for controlling biodeterioration and consolidants for disintegrated areas – were undertaken.
- The Archaeological Park of Facatativa, where panels of rock art were deteriorating not only as a result of exposure to the natural environment, but also as a result of exposure to humans. Both biodeterioration and vandalism in the form of graffiti were damaging to the rock art panels. The panels received conservation attention for both problems.
2) and historical monuments, such as:
- The Jimenez de Quesada Monument in the city of Bogota, which had been damaged as a result of vandalism in the form of graffiti. The monument received a conservation treatment that included both the removal of the graffiti as well as the application of a coating to protect the monument against future graffiti vandalism.
In all of the cases that she presented, Maria spoke about the effect of the political, social, and economical climate on the sites’ conservation and preservation. She stressed the impact that such climates have on cultural heritage, from the care to the destruction of sites. She explained how various political, social, and economical circumstances have led her and her colleagues to determine goals and procedures for conservation and preservation projects. I found these concepts very powerful. For me, this presentation was a strong reminder of the complexities involved in the preservation of cultural heritage.
42nd Annual Meeting – RATS Joint with Objects Session, May 30, “Technical Study and Conservation of the ‘Bat Wing Ship,’ Background, Challenges and Surprising Discoveries, Lauren Anne Horelick , Objects Conservator, Smithsonian National Air and Space Museum
The compelling object at the center of this paper is an experimental prototype of a Nazi German jet powered fighter aircraft discovered by the Allies at the end of World War II and brought to the United States for study. Designed by the Horten Brothers (Reimar and Walter), this craft with a steel structure, paper-thin plywood veneers, and no vertical tail is regarded as a design predecessor to the stealth bomber. The aircraft, a model Horten Ho 229 v3 (the third and final version of this particular airframe) was captured when it was near completion in the Gotha workshop http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19600324000 Charcoal was said to have been added to the construction adhesives to make the aircraft invisible to radar.
While always a favorite of air flight/military history buffs, this craft has never been exhibited and has been the subject of increased interest in recent years due to what the paper’s author describes as a “sensationalized” documentary entitiled “Hitler’s Stealth Fighter.” This video, available on YouTube, is replete with inaccuracies including the assertion that it is stored in a “secret government warehouse” when, in fact, its current home is the Smithsonian’s Paul E Garber Facility in Suitland, Maryland. However, it will soon be moved to another disclosed location – The Udvar-Hazy Center in Chantilly, Virginia where it will have its big reveal.
In preparation for this move, conservators at the Smithsonian NASM carried out a technical study to inform treatment protocol for the stabilization of the unstable and extensively delaminating veneers. They sought to characterize and identify the adhesives and other materials employed and, in particular, seek evidence for the presence (or apparent lack) of charcoal.
The aircraft is 55.4 feet wide with a tubular steel frame. The engine rests in the center of the craft and it is covered in a plywood skin. There is a clear canopy for the pilot. Due to complications of working on the object in its storage location, the decision was made to disassemble the damaged plywood portions to allow for treatment of the panels in the conservation lab. The composite materials that were examined and analyzed included the plywood board, structural supports and spacer blocks including the adhesives used to attach these portions to one another.
After a literature review of plywood available in Germany before WWII, reference materials were acquired for the potential materials. A sampling protocol was developed and the object and reference samples were examined under visual and Polarized Light Microscopy, FTIR, Raman, and for selected samples XRD was employed. (There may have been other methods employed that I missed in my notes– GC-MS and 3-D microscopy were mentioned in the abstract – sorry if I have omitted something significant.) The analysis was done in conjunction with the Museum Conservation Institute.
The analyses yielded some unexpected results as some of the wood sample results varied from those specified by the Horten Brothers (as reported in their interrogation). However the substitutions of European Beechwood/Scots Pine for the specified birch was not very surprising to the authors given the materials shortages at the end of WWII. The adhesives tested were identified as urea formaldehyde and phenol formaldehyde. Confirming the presence of charcoal in the black paint/adhesive layers proved elusive. The black particles were difficult to separate from the matrix. PLM examination did not support the charcoal identification and they were found to be amorphous with XRD. FTIR analysis pointed to the presence of cellulose, hemi cellulose and phenolics. This could mean oxidized or charred wood – or neither.
Plans for treatment do not include repainting damaged areas as the author mentioned a growing trend toward exhibition of aircraft in a less heavily restored state. Beech veneers will be employed in areas of loss but were unavailable in the United States in the <1mm thickness required so must be ordered from Germany. Because the urea formaldehyde has cross-linked with age and become insoluble, the conservators are not as concerned as they might have been about adding new materials when they choose an adhesive to stabilize the veneers.
Details and updates on this research project and the treatment are available on the on the National Air and Space Museum’s Airspace blog http://blog.nasm.si.edu/restoration/horten-h-ix-v3-bat-wing-ship-may-2014-update/ The Bat Wing Ship is poised to be a popular attraction when it goes on exhibit – I know my interest has been piqued by this interesting talk!
42nd Annual Meeting (Objects Session 5/31/14) – "Testing and implementation of microclimate storage containers for small metals and plastics" by Dana K. Senge
Dana’s talk – the last of the Objects session talks given at AIC’s 42nd Annual Conference in San Francisco – presented the results of multiple tests conducted by the National Park Service (NPS) Intermountain Region Museum Services Program, evaluating several readily available materials for their ability to protect sensitive objects from less-than-ideal climate conditions. Tests sought to identify the best methods for long-term storage of two distinctly different categories of collections materials: archaeological metals and historic plastics. The ideal solutions would be cost effective and easy-to-use, would allow for easy monitoring and access, and could be consistently applied across all NPS sites.
Archaeological Metals
Various storage systems for archaeological metals have been employed at NPS sites in the past, including Stewart boxes, 2-4 mil polyethylene (PE) bags with twist ties, and heat-sealed Marvelseal enclosures in combination with desiccants and/or scavengers.
Following the work done by JP Brown (2010) and Alice Paterakis (2011), Dana did some short experiments to confirm that resealable PE containers with silicone gaskets held a microclimate better than similar containers without gasketing. This being established, she added data loggers and twice the calculated amount of desiccant recommended for the container’s volume, and conducted a longer test in three locations – Arizona, where storage conditions were generally dry (about 35% RH); Montana, where conditions ranged from 25-45% RH; and Texas, where conditions fluctuated around 50% RH. Even under the most humid conditions in TX, the worst-performing silicone-gasketed PE boxes only allowed an increase of 2% RH over the course of the year-long test period. Measurement of the TX test box after a second year registered only another 2.7% increase in RH. Based on this set of experiments, Dana calculates that this particular setup would only require recharging with desiccant every 5 years if a change of less than 15% RH was desired. In addition, Oddy testing of the materials involved in the system confirmed that there was nothing harmful being off-gassed.
Historic Plastics
To find an ideal solution for historic plastics, Dana started by consulting Yvonne Shashoua’s 2008 publication, Conservation of Plastics. She learned that different polymers have wildly varying requirements for safe storage: cellulose nitrate (CN) and cellulose acetate (CA) need ventilated or scavenged environments to slow deterioration, while natural rubber fares better in anoxic environments, and polyvinyl chloride (PVC) calls for only non-absorbent glass or Mylar fabrication materials. The deep trays with Tyvek covers that had been in use at NPS since the 90s were not effective, so alternatives were sought.
For use with CN and CA, several box designs were evaluated for their ability to ventilate the space and prevent dust accumulation inside the box. Acid-free board boxes were made with slatted or screened walls and were tested without lids, with Hollytex lids, or with acid-free board lids. Inside the prototype boxes, Dana placed a deteriorating CA shower curtain ring along with a sticky surface to determine how much dust found its way in, and A-D Strips to monitor for the buildup of harmful acetic acid vapors. Findings supported the use of a blue-board lid, as it prevented the most dust over a month-long period. Though screened and slatted boxes did equally well, the screened boxes were found to be easier to construct. No harmful buildup was detected by the A-D strips in any of the boxes.
As a space-saving alternative to ventilated storage, Dana next evaluated several common scavengers in conjunction with the previously described resealable PE containers. In order of their performance (worst to best), they were Kodak Molecular Sieves, a single MicroChamber board, Getter Pak, two MicroChamber boards, and Zorflex. The most effective adsorbent, Zorflex, prevented acetic acid build-up in the container for 18 days. Interestingly, each scavenger tested lowered the humidity in the box to some extent initially, though it did eventually rebound. A second round of tests that doubled the amount of scavenger found no benefit to doing so. Future work will include evaluating activated carbon cloth, and rerunning the above described scavenger tests on boxes containing a larger amount of deteriorating CA to see if the products can keep up with increased volumes of off-gassed acetic acid. She would also like to test resealable glass containers in this capacity.
Although storage for PVC objects was not extensively discussed, Dana mentioned that she has been using and is pleased with heat-sealed 1 mil Mylar enclosures. She prefers the use of a single-impulse heat sealer to a double-impulse model to make the enclosures.
Finally, Dana made a point to address a few limitations of the systems she evaluated for this paper, including size (the largest silicone-gasketed PE containers she’s been able to find only measure 9 x 12 x 6 inches) and the need for a robust monitoring/maintenance plan.
Questions/comments after the talk:
- One talk attendee mentioned that she had found much larger gasketed PE boxes, but that they didn’t necessarily seal well because of the distance between the clamps, especially on the long edges. She recommended testing the container with water – if it’s not watertight, it won’t be airtight either!
- A question was posed about the efficacy of these systems compared to non-gasketed PE boxes that were sealed with aluminum tape instead. Dana stated that aluminum tape was not evaluated in this round of testing.
- Dana, though she didn’t mention brand names, cautioned that some brands of containers definitely held a better seal than others. Test your enclosures first!!!
I really enjoy hearing about research with practical applications. Thank you, Dana, for a well presented and interesting talk!!
42nd Annual Meeting – Research and Technical Studies Session, May 31st, "X-ray Micro Tomography Analysis of Western Red Cedar Secondary Phloem by Peter McElhinney"
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.
Recoloring Faded Taxidermy – Research into the Properties and Applicability of Dye Materials for Conservation Treatment.
In 2013, the American Museum of Natural History and Yale University’s Center for Conservation and Preservation were awarded an Institute for Museum and Library Services’ (IMLS) National Leadership Grant to fund a three-year project devoted to the development of best practices for recoloring faded taxidermy mounts displayed primarily in habitat dioramas: Recoloring Faded Taxidermy – Research into the Properties and Applicability of Dye Materials for Conservation Treatment.
Follow the research through the project blog – In Their True Colors: Developing New Methods for Recoloring Faded Taxidermy [http://intheirtruecolors.wordpress.com/]. The blog is now live – add your comments and questions to be addressed in subsequent blog posts!
After years of display under bright lights, and harsh temperatures and humidity, many taxidermy mounts have become discolored and faded. Techniques for restoring the lost colors of damaged natural history collections are limited and under-researched. This knowledge gap puts at risk collections of great educational value, especially as some historical specimens represent species that are endangered, if not already extinct.
The project conservators are interested in developing re-coloring methods that would minimally alter the texture or sheen of hair and fur, and could be as reversible or re-treatable as possible.
This research will foster cross-disciplinary partnerships between conservators and scientists with varying forms of expertise, helping to bridge the institutional gap between natural history, art, and history museums and collections.
The IMLS-funded project will build upon promising results from a pilot study conducted by the Museum into the use of certain dyes, such as those used in certain specialized printing inks, to recolor taxidermy hair and fur. The next few posts will present the results of the restoration project that resulted in the dramatic restoration of the faded specimens in the habitat dioramas in the Museum’s Bernard Family Hall of North American Mammals.
The findings from the study, which the Museum conservators presented at 2012 annual meetings of the Society for the Preservation of Natural History Collections (SPNHC) and the American Institute for Conservation (AIC) and published in the October 2012 International Committee of Museum, Natural History Collections Working Group Newsletter, were received with immense interest by practitioners and researchers alike. Together with results from a national survey among conservation professionals, it was evident that there was a strong need for comprehensive research to explore additional materials and discover an appropriate method for recoloring faded taxidermy in museum collections.
Posted on behalf of Elizabeth Nunan
Associate Conservator
Natural Science Collections Conservation
American Museum of Natural History
Say Yes to Service
Spring is coming, believe it or not, and nominations committees are currently canvassing our membership, looking for people to run in the spring elections. Sadly, most of the people they ask will follow Nancy Reagan’s instructions to the letter: they’ll just say no.
Friends, service work for AIC is not a highly-addictive drug that will destroy your life. Consider saying yes. Everyone seems to focus on how much extra work is involved in service. It’s true: service positions do involve work. Also true: most don’t involve that much work. And nobody ever talks about the fact that this work is often very interesting, that you might actually like it.
For example, as a member of the Education and Training Committee, I review scholarship and workshop applications from our entire membership. As a result, I get a broad overview of what people in all sub-disciplines are doing and it’s fascinating. The ETC also gives me the opportunity to work on bigger issues in our field, and in doing so I get to collaborate with conservators who have completely different experience and perspectives.
I’m also currently the program chair for the Objects Specialty Group. This isn’t the first time I’ve chaired conference sessions and I’m going to tell you a secret: it’s crazy easy and highly rewarding. Do I occasionally devote nights or weekends to reading abstracts, papers, and corresponding with authors? Yes. Is it interesting and worthwhile? Also yes. There is no better way to hear talks you want to hear than to chair a session and choose them yourself. This year for OSG, we had over 70 abstract submissions and not a single one of them was bad. With room for only 18 papers, the review committee had to make difficult decisions. As depressing as it is to reject 50+ good talks, think about the flip side: from 100% inspiring, solid submissions we were able to choose the papers we thought had the most to offer. As program chair, I was also able to plan a cocktail party for our group.
Admittedly, there are truly bad times to take on service responsibilities. Maybe you have a new baby, or a new job, or someone in your family is very sick. But if you’re simply waiting for the right time, the good time, then stop. It’s not coming. Two years from now you will not be lying on the couch eating bonbons and thinking, “hmm….I have so much leisure time….now might be a good time to do some service for AIC.” We’re all busy. I work a 55-60 hour a week job and, like all of us, have a life outside of work/conservation. But I make time for service.
There are a lot of reasons to say yes to service work: you’re interested in a particular initiative, you want to give back, you want to be in a position to effect change. I do it because I like it. Think about it. You might like it, too.
POLES, POSTS AND CANOES: THE PRESERVATION, CONSERVATION AND CONTINUATION OF NATIVE AMERICAN MONUMENTAL WOOD CARVING.
CALL FOR PAPERS
JULY 21ST – 22ND, 2014, HIBULB CULTURAL CENTER AND NATURAL HISTORY PRESERVE, TULALIP, WASHINGTON
The call for papers for Poles, Posts and Canoes: the Preservation, Conservation and Continuation of Native American Monumental Wood Carving (July 21st – 22nd, 2014, Tulalip, Washington) has been extended to February 28th, 2014. We still have a few spaces for presentations, especially those angled towards general collections management, display and use of these objects in native and non-native managed museums, and the use in a museum setting of traditional means of maintenance.
This two day symposium (preceded by an opening ceremony and meal on the evening of July 20th) will gather Native and non-Native museum professionals, tribal members, and contemporary Native carvers to discuss the challenges of preserving and exhibiting historic monumental wood carvings from both a Native and Non-Native view point. It will also serve to connect Native carvers and the museum community in the hope that the resulting dialogue will help support the continued development of this traditional art form. The format of this gathering is aimed at encouraging discussion, so presentations will be relaxed and brief, and an equal amount of time will be scheduled for general discussion of the topics addressed.
Registration will open January 21st, 2014, and a provisional program will be available at that time.
Further information and details about the conference will be posted at www.hibulbculturalcenter.org/Events/Symposium/
Call for papers:
The meeting is heavily focused on inclusive discussions amongst participants, therefore we are seeking short presentations (10 – 15 minutes maximum) that encourage constructive dialog. While technical papers are welcome, we ask that presenters keep in mind the broad background of the expected attendees. The event will be recorded and the proceedings published.
Proposals for presentations on the following topics are invited:
- The history behind the past care of poles, posts, canoes and similar large Native carvings held in conventional museum settings.
- The care of these objects in Native museums and communities from the Native perspective.
- What types of large artifact conservation treatments and care work best in Native and non-Native museums?
- The importance and relevance of these objects for the personal visions of the Native carver.
- The potential use of traditional methods and materials in the preservation of existing objects in collections.
- How can conservators, custodians and Native carvers bridge the communication gap and support each other’s work?
- How can a balance be struck between technical and non-technical methodologies?
- How can we define a range of “best practices” in Native museum collections regarding treatments, storage, moving and mounting techniques for this material?
Information to be included in your proposal:
- Presentation proposal should be not more than 250 words.
- Please include a 100 word summary that will be included on the conference website, should your paper be accepted.
- Provide your name, occupation/institution and contact information, including e-mail address.
- Indicate the format of your presentation – PowerPoint, presentation from written notes, etc.
Deadline for submission: February 28th, 2014.
Please submit proposals to: J. Claire Dean at info@hibulbculturalcenter.org (include “PPC paper proposal” in the subject line). You will be notified by e-mail whether or not your paper has been accepted by March 24th, 2014.
For full details of proposal requirements, as well as registration information for both the symposium and the totem pole maintenance workshop that follows on July 23rd – 25th July, please visit http://www.hibulbculturalcenter.org/Events/Symposium/