UCLA/Getty Conservation Program

A graduate conservation training program focusing on the conservation of archaeological and ethnographic materials


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“Animal, Vegetable, Mineral?” – Identifying mystery fibers in the field

When conservators are working on archaeological excavations, their work often encompasses many different aspects of field conservation.  This can include materials identification and characterization, lifting fragile artifacts and aiding in archaeological research.  No matter what facet of the project they are involved in, the work can be challenging without the comforts of a well-stocked lab and requires lots of problem solving and improvisation.  Last summer while working on the Ancient Methone Archaeological Project, we were faced with the challenge of trying to identify an unusual looking fibrous material which required us to MacGyver a transmitted light microscope to aid in the examination and identification of the mystery fibers.

During the 2014 season, a team of geomorphologists working on the project were taking core samples in an area thought to be an ancient harbor.  In one of the cores, they pulled out a clump of fibers they thought might be cordage (fig. 1).  They brought the samples to the conservation lab to see if we could identify the fibers and determine if it was cordage or the remnants of woven fibers. Some samples were set aside for radiocarbon dating and the remainder of the sample, which was still bound in sediment, was examined.

Figure 1. Clump of fibers found in soil core by Geomorph team. Photo: Ancient Methone Archaeological Project

Figure 1. Clump of fibers found in a core sample taken by the Geomorphology team. Photo: Ancient Methone Archaeological Project

The initial macroscopic examination revealed that the fibers appeared translucent (fig. 2).  They seemed to be grouped into bundles and some of these bundles initially appeared to cross each other, giving the impression of a woven structure.

Fgiure 2. Detail of the fibers encased in the sediment.  The fibers are translucent and are grouped in bundles.  Photo: Ancient Methone Archaeological Project

Fgiure 2. Detail of the fibers encased in the sediment. The fibers are translucent and are grouped in bundles. Photo: Ancient Methone Archaeological Project

The fibrous material was encased in a gray, silty sediment, which appeared to include quartz, foliated phyllosilicates/sheet silicates (like mica, vermiculite, etc.) (fig. 3), as well as small shells, both fragmented and whole (fig. 4). The sample was initially wet, and was allowed to slowly dry out in the lab. The sediment was gently pushed away using a pin-vise under binocular magnification, to better define the structures and reveal diagnostic features of the material for its identification (fig. 5).  Photographs of the fibers were taken using the DinoLite USB microscope (7013MZT Series). During this examination and initial cleaning, the fibers were found to be very brittle.  Though they appeared to be in bundles, they were not actually bound to each other and could be easily separated.

Figure 3.  During cleaning, plate-like inclusions were found in the soil and between the fiber bundles.  These inclusions resembled sheet silicates like mica. Photo: Ancient Methone Archaeological Project

Figure 3. During cleaning, plate-like inclusions were found in the soil and between the fiber bundles. These inclusions resembled sheet silicates like mica. Photo: Ancient Methone Archaeological Project

Figure 4.  Small shells or shell fragments were also found in the deposit. Photo: Ancient Methone Archaeological Project

Figure 4. Small shells or shell fragments were also found in the deposit. Photo: Ancient Methone Archaeological Project

Figure 5.  After some initial cleaning to remove soil, more of the fiber bundles and associated materials are visible. Photo: Ancient Methone Archaeological Project

Figure 5. After some initial cleaning to remove soil, more of the fiber bundles and associated materials are visible. Photo: Ancient Methone Archaeological Project

Though examination with a stereomicroscope helped to reveal more about the fibers and the structure of the bundles, we were not able to clearly identify what the fibers were.  We felt that examination using transmitted light microscopy would be the most helpful since it could highlight any morphological features in the fiber that could aid in identification.  So we set out to make one armed with our DinoLite microscope and a flashlight. The set up turned out to be quite simple. We just needed to be able to shine a light through the fibers from below and examine the fibers at a high magnification using the DinoLite (fig. 6). We took a fiber bundle from the sediment and placed it on a multi-bulb LED flashlight (fig. 7).  This flashlight was flat and rectangular and the ideal shape for our light source since the fiber samples could be directly placed on the top surface of the flashlight.  The fact that the flashlight was flat also meant it was easy to position the light source under the microscope where needed (fig. 8).

Figure 6.  We created a transmittled light microscope using the DinoLite USB microscope and an LED flashlight which acted as the transmitted light source. Photo: Ancient Methone Archaeological Project

Figure 6. We created a transmittled light microscope using the DinoLite USB microscope and an LED flashlight which acted as the transmitted light source. Photo: Ancient Methone Archaeological Project

Figure 7. We placed samples of the fibers directly onto the flashlight during examination. Photo: Ancient Methone Archaeological Project

Figure 7. We placed samples of the fibers directly onto the flashlight during examination. Photo: Ancient Methone Archaeological Project

Figure 8.  Using our transmitted light  microscope to examine the fibers.  Macguyver would be proud. Photo: Ancient Methone Archaeological Project

Figure 8. Using our transmitted light microscope to examine the fibers. Macgyver would be proud! Photo: Ancient Methone Archaeological Project

Looking at the fibers in transmitted light, we observed a central void within some of the fibers.  Since we were considering the possibility of the fibers being organic in nature, we thought these central voids could be the medulla or lumen of an organic fiber (fig. 9). However, no other morphological features were present that helped us determine at this point what the fibers were.

Figure 9. Looking at the fibers under transmitted light, we could see they had a central void, which initially made us think this was the lumen of a plant fiber or medulla of an animal fiber. Photo: Ancient Methone Archaeological Project

Figure 9. Looking at the fibers under transmitted light, we could see they had a central void, which initially made us think this was the lumen of a plant fiber or medulla of an animal fiber. Photo: Ancient Methone Archaeological Project

We were also able to take a look at the cross-section of the fibers with the addition of a polarizing lens on the DinoLite (fig 10). Some fibers appeared hexagonal in section (fig. 11).  Some of the ends of the fibers ended in a point or were triangular in shape.

Figure 9.  With the addition of a polarizing lens on the DinoLite we were able to see the cross-sections of some of the fibers.  Some appeared hexagonal or triangular in section. Photo: Ancient Methone Archaeological Project

Figure 9. With the addition of a polarizing lens on the DinoLite we were able to see the cross-sections of some of the fibers. Some appeared hexagonal or triangular in section. Photo: Ancient Methone Archaeological Project

Figure 11.  Details of the fibers showing their shape in section.  Photo: Ancient Methone Archaeological Project

Figure 11. Details of the fibers showing their shape in section. Photo: Ancient Methone Archaeological Project

Further cleaning revealed a tiered growth structure that resembled the growth of minerals more than plant or animal fiber bundles (fig. 12).  The inclusion of sheet silicates in relation to the fibers, either located between bundles or within them further suggested these fibers were mineral.  In searching the literature we came across images of asbestos minerals which looked similar to our mystery fibers.  Several types of asbestos minerals are fibrous in appearance (fig. 13), and can occur near phyllosilicate deposits.  Armed with this information we concluded that the fibers were definitely mineral in nature and could possibly be asbestos.

Figure 12.  Fiber bundle after cleaning. Photo: Ancient Methone Archaeological Project

Figure 12. Fiber bundle after cleaning. Photo: Ancient Methone Archaeological Project

Figure 13. An image of crocidolite, a fibrous form of the mineral riebeckite, and one of the 6 recognized forms of asebstos minerals.  © Raimond Spekking / , via Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/b/b3/Krokydolith_-_Mineralogisches_Museum_Bonn_%287385%29.jpg

Figure 13. An image of crocidolite, a fibrous form of the mineral riebeckite, and one of the 6 recognized forms of asebstos minerals. © Raimond Spekking / , via Wikimedia Commons https://upload.wikimedia.org/wikipedia/commons/b/b3/Krokydolith_-_Mineralogisches_Museum_Bonn_%287385%29.jpg

Luckily we were able to bring a sample of the fibers back with us and conduct some analysis in the UCLA/Getty Conservation labs. And we were quite surprised by the results!  It turns out we were correct in deducing the fibers were mineral in nature, but we were incorrect about which mineral. XRF and XRD analysis did not find any asbestos minerals in the sample, but instead the fibers were identified as calcite (fig. 14).  Though we had never seen calcite that was fibrous in appearance, it is one of the mineral’s crystal forms. An example is shown in fig. 15 where you can see the SEM image of “lublinite”, a needle-type of calcite whose form is thought to be associated with the activity of microorganisms.

Figure 14. XRD analysis results showing the fibers were composed of calcite.

Figure 14. XRD analysis results showing the fibers were composed of calcite.

Figure 15. SEM image of lublinite, the fibrous form of calcite.  Image taken from: http://www.speleonics.com.au/jills/bymineral/lublinite.html

Figure 15. SEM image of lublinite, the fibrous form of calcite. Image taken from: http://www.speleonics.com.au/jills/bymineral/lublinite.html

Even though we were not able to identify the fibers as calcite in the field, the use of a stereomicroscope and our makeshift transmitted light microscope certainly helped distinguish their mineral nature and rule out plant or animal origins.  And now that we’ve figured out how to make a transmitted light microscope and tested it out, we’re ready for any future material ID questions that would require one.

MacGyver looks on and smiles at our ingenuity.  Photo: http://macgyver.wikia.com/wiki/List_of_problems_solved_by_MacGyver

MacGyver looks on and smiles at our ingenuity. Photo: http://macgyver.wikia.com/wiki/List_of_problems_solved_by_MacGyver

Written by the 2014 Ancient Methone Archaeological Project Conservation Team: Heather White (UCLA/Getty Program Grad Student, Class of ’16), Vanessa Muros (Conservation Specialist/Lecturer, UCLA/Getty Program) and Anna Weiss (Campus Art/Artifact Collections Coordinator, Conservator, Univ. of Chicago)


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The Conquistador’s Coat: Characterization of a surface coating on a Guatemalan polychrome mask

This past spring quarter, for the course “Conservation Laboratory: Organics III”  (CAEM 241), I had the opportunity to examine and treat a polychrome mask (X91.470) from the collection of the Fowler Museum at UCLA.  The polychrome mask is made of carved wood  and is  likely meant to depict the face of a conquistador, with detailed curling hair, a long beard and mustache, and a light complexioned, pink face.

Masks such as this one are commonly used in ceremonial dances in Guatemala, and one such as this may have been used in the Dance of the Conquest, a dramatic dance that depicts the Conquest of Guatemala by the Spanish in 1524 (Pieper 1988: 39) . You can see a portion of this dance in this YouTube video, where several of the dancers are wearing a mask similar in appearance to the Fowler conquistador mask.

The mask is painted with thick layers of paint that are currently heavily obscured by a thick accumulation of soiling that is likely on top of a discolored surface coating. Guatemalan dance masks are traditionally professionally maintained by costume shops called morerias, which apply fresh paint to keep them looking new.  The age of the mask is not necessarily considered a marker of value, and it is actually preferred that the masks look new and well maintained when they are danced.  Some masks may be blessed by an indigenous Shaman or Catholic priest (Pieper 2006: 43-45) .  Historic accounts of the maintenance of these masks do not refer to the application of any surface coatings as a protective measure for the polychromy.

Description of the coating

The majority of the painted surface of the mask is obscured by a thick layer of a dark, grimy material with embedded soiling (fig. 1-2).  It is unknown when or for what purpose the coating was applied to the mask, but it may have been applied for surface protection of the polychrome or to consolidate flaking paint.

Fig_1a_X91.470 Fig2c_X91.470

Figures 1 and 2. An image of the front of the Conquistador’s mask (X91.470) (left) with a detail (right) of the area of the nose showing the discolored surface coating.

Under stereo binocular magnification (7-45x), the material has a varied appearance, at times appearing like a matte coating that is heavily embedded with soiling of a granular nature (fig. 3), at times flaking (fig. 4), and in other instances appearing thinner, with a somewhat sticky texture, but less accumulated matte material (fig. 5).

Fig3_X91_470_07X

Figure 3. Soiling on the mask that is granular in nature

Fig4_X91_470_07X

Figure 4. Dark surface material that is flaking.

Fig5_X91_470_07X

Figure 5. Some of the dark material on the surface appeared thinner and sticky, and some areas had a matte appearance.

There are also areas where the surface coating has a wrinkled appearance, as if it has shrunk and pulled away from the surface, and in these cases it appears to be pulling the paint layer with it (fig. 6).  The wrinkled areas look the way that paint looks when a commercial paint stripper is applied.  In all of its iterations, it appears to be inextricably linked with flaking paint layers beneath it (fig. 7).

Fig6_X91_470_07X Fig7a_X91_470_1X copy

Figures 6 and 7. In some areas the surface coating appears as if it shrunk and pulled away (left). Regardless of the appearance or texture of this coating it is inextricably linked with flaking paint layers (right).

There are a few areas where the obscuring dark coating is not as present.  In these areas, it appears that there may have been an attempt to remove it, which resulted in peeling away of the top paint layer as well (fig. 8a and b).  In these instances, the pink paint film has been pulled away and is folded over onto the surface of the mask and adhered in place. The areas of folded paint film appear to be brittle and have shattered in some locations along the edges.  There is a sticky, light brown resinous material that has accumulated in the crevices of these surfaces, which is likely deposited residue from the surface coating. In addition, a distinct layer of soiling has accumulated on top of the coating.  Much of the soiling appears embedded within the coating, but there is also loose surface dirt that can be moved with a soft brush.

Fig8a_X91.470 Fig8b_X91_470_07X_
Figures 8a and b. In some areas, it appears as if there was an attempt to remove the coating (left) which resulted in peeling away of the top paint layer (right).

UV Examination

The object was illuminated with ultraviolet radiation at λexcmax=300-400nm and captured with a Nikon D90 digital camera affixed with the PECA 916 filter (visible range). The soiled coating that covers the face appears largely absorbing.  Areas of fluorescence occur where the flesh colored paint is exposed without the coating (fig. 9).

Figure 9. Under examination with a UV light (λexcmax=300-400nm) the soiled coating appears largely absorbing.  Areas of fluorescence occur where the flesh colored paint is exposed without the coating.

Figure 9. Under examination with a UV light (λexcmax=300-400nm) the soiled coating appears largely absorbing. Areas of fluorescence occur where the flesh colored paint is exposed without the coating.

Solubility Testing

Solubility testing was conducted in situ on the mask with room temperature deionized water, warm deionized water, acetone, ethanol, toluene, and mineral spirits.  The coating was unresponsive to cool water, acetone, ethanol and mineral spirits, but a slight change in appearance was noticed when toluene was applied, though none of the coating was removed onto the swab.  This surface change was fleeting and the coating returned to its original appearance immediately.  Just to be certain that the coating was insoluble in toluene, the application of toluene on a small sample of coating that had flaked off of the surface was observed under stereo binocular magnification at magnifications of 7-45x.  No dissolution or swelling of the coating material was observed (fig. 10).

Figure 10. No dissolution or swelling of the coating material was observed in toluene.

Figure 10. No dissolution or swelling of the coating material was observed in toluene.

The mask was undergoing treatment because the painted surface was unstable and was lifting and flaking.  Gelatin was under consideration as a consolidant for the flaking paint and therefore warm water was also tested to ensure that a warmed gelatin solution could be used without disrupting the appearance of the coating.  Unfortunately the warm water was found to swell and eventually solubilize the coating so that it could be swabbed away with gentle pressure.  The interaction of the coating with warm water was further investigated by observation under stereo binocular magnification.  As the sample soaked in the warm water the brown material on the sample surface swelled into fluffy blobs on top of a more transparent, clear base.  Over a period of time the clear, striated section of the sample also appeared to swell slightly (fig. 11).  Because warm water was observed to have an effect on the coating, a small cleaning test was conducted in a discreet area of the mask using warm deionized water applied by swab under stereo binocular magnification.  The coating was greatly reduced using this method and it is very likely possible that it could be removed simply using warm water, if removal were desired.  Though the solubility in warm water introduced a possible complication with using a warm, aqueous consolidant such as gelatin, the fact that the gelatin would remain soluble in water was also a possible advantage to using this consolidant; should the removal of the consolidant be desired in the future, it would be beneficial if it was not consolidated in place with a system using toluene (the only solvent besides water that did not affect the paint layers below) for toxicity reasons.

Figure 11.  Swelling of the coating was observed in warm water.

Figure 11. Swelling of the coating was observed in warm water.

Additional Microscopic Observations

Two small samples of the pink paint was removed from a discreet area of the mask where the paint layer contained a layer of the dark coating and was observed to be flaking.  This flake was viewed in transmitted light using an Olympus BX-51, polarized light microscope at magnifications between 50-200X.  Using this technique, it was not possible to observe the layers as distinct entities, however, at the edge of the paint flake and within interstices of the flake, small sections of the coating could be observed.  It appeared to have a somewhat clear and amorphous structure (fig. 12a and b).

Fig14a_x91_470_coating_11 Fig14b_x91_470_coating_21).
Figures 12 a and b. Examination of a paint flake with the coating viewed under transmitted light.

In addition, several small samples of the coating were removed from the mask during a light surface cleaning procedure.  These samples were soaked in warm water as described above, in order to further characterize the solubility of the material.  These samples were viewed in transmitted light under high magnification and also in cross-polarized light. (fig. 13a and b) The samples appeared to swell from exposure to the water.  The material was quite clear, and had the appearance of an organized cellular structure in some areas.

Fig15a_x91_470_coating_31 Fig15b_x91_470_coating_32
Figures 13a and b. Examination of the coating using transmitted (left) and cross-polarized light (right) after swelling in warm water.

Spot testing

Two microchemical tests were conducted in the hope of possible identification of materials present: a test for polyamides using p-dimethylaminobenzaldehyde (Odegaard et al. 2000: 170-171), and a test for protein using copper (II) sulfate (Odegaard et al. 2000: 144-145).

The test for polyamides was conducted to confirm or deny the presence of nylon, had the mask been treated with soluble nylon (N-methoxymethyl nylon, a chemically modified form of nylon that is produced by treating nylon with formaldehyde). Soluble nylone was a common consolidative conservation treatment for powdering or flaking paint beginning in the late 1950s.  Objects that have undergone treatment with soluble nylon have been observed over time to exhibit numerous problems including accumulation of disfiguring and obscuring soiling in the nylon film, the film exerting strong contractile forces which peel away surface layers from objects, and the film losing flexibility and becoming insoluble (Sease 1981).  These descriptions of the degradation characteristics of soluble nylon in the literature were similar to the appearance of the coating on the Fowler mask. Neither the age of the mask nor its conservation history are known, and it was possible it could have been treated at a time when soluble nylon was a popular conservation treatment. The result of the spot test was negative and was compared to a known positive result (color change to red of filter paper used in the test) from a nylon sample taken from the ResinKit™.

The protein test was conducted because of the coating’s swelling effect in warm water.  In addition, from the literature it is known that at high RH levels animal glue films can experience severe shrinkage due to contraction of the glue matrix, and in some instances the coating appears to be undergoing contractile shrinkage as described (Schellmann 2007).  The result of the protein test was negative and was compared to a known positive sample of gelatin.

Conclusion

Based on the above observations and testing, the material constituents of the coating could not be identified.  Nylon-based (such as soluble nylon) and protein-based (such as animal glue) coatings were ruled out based on the spot testing results.  Knowing that the material is soluble in warm water is important information should the removal of the coating be desired in the future.  At this time, because the nature and purpose of the coating have not been identified, its removal would not be an appropriate course of action, so it will be left intact.  An additional problem posed by the presence of the coating is that the paint layers below it are flaking, and the coating may be contributing to or in fact causing the flaking.  In order to consolidate the paint layers below without removing the coating first, the coating and accumulated soiling also become consolidated as a result.  Even though warm water has the ability to swell or solubilize the coating, mechanical action is also required to remove it.

Though the warmed consolidant did have the potential to interact with the coating, care was taken to only flow the gelatin under lifting or detaching paint flakes and to try to avoid saturating the coating with consolidant.  This worked rather well in the areas of pink polychromy.  When cleaning was required around the consolidation site, this was done immediately, and the coating was not affected.  In the areas of the hair and beard, the nature of the coating was somewhat different, as described above (fig. 4).  When this iteration of the coating came into contact with the warm gelatin, it solubilized quite easily.  Again the focus of the treatment was consolidation of localized areas of active flaking or evident wood deterioration, and care was taken in choosing sites in which to introduce the consolidant by brush without disrupting the coating.  When the consolidant was applied with care under binocular magnification, the coating was not at risk of being removed.  Furthermore, by using this aqueous consolidant, the solubility of the coating in warm water should not be affected, should its future removal be desired.

References

Odegaard, Nancy, Scott Carroll, and Werner S. Zimmt. Material characterization tests for objects of art and archaeology. Archetype, 2000.

Pieper, Jeanne, and Jim Pieper. Guatemalan Masks: The Pieper Collection. Craft and Folk Art Museum, 1988.

Pieper, Jim. Guatemala’s Masks and Drama. University of New Mexico Press, 2006.

Schellmann, Nanke C. “Animal glues: a review of their key properties relevant to conservation.” Studies in Conservation 52, no. Supplement-1 (2007): 55-66.

Sease, Catherine. “The case against using soluble nylon in conservation work.” Studies in Conservation 26, no. 3 (1981): 102-110.


Written by Lesley Day (’16)


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Class of 2016 Summer & 3rd Year Internships

The quarter is coming to an end and students are busy finishing up treatments and thesis projects, as well as writing papers and studying for finals. On top of all that, they’re busy getting ready to leave LA for their summer and 3rd year internships. Below is a list of all the great places they’ll be working at in the upcoming year.

We wish them good luck on their internships and safe travels!


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ANAGPIC 2015, here we come!

Our students and faculty are getting ready to head east to attend the 2015 ANAGPIC conference this week. This year, the conference will be co-hosted by the Winterthur/University of Delaware Program in Art Conservation (WUDPAC) and the University of Pennsylvania’s graduate program in Historic Preservation. This is the first time that UPenn will be hosting ANAGPIC. They, along with Columbia University’s Historic Preservation program, joined ANAGPIC a couple of years ago. The addition of these programs broadens the scope of the papers presented and provides additional opportunities for students and preservation professionals to share information about their recent research and projects.

The UCLA/Getty Program will be well represented with 2 speakers and 4 posters. Abstracts of our program’s presentations are found below. For a full list of papers/posters presented and more information on the conference, you can check out the ANAGPIC 2015 website. And make sure to check out our Facebook page and blog for photos from the conference.


Papers

Torqua Cave: Documentation and Condition Assessment of Catalina’s Rock Images
Tom McClintock

The site of Torqua Cave is a rock shelter on Catalina Island, located 20 miles off the coast of Southern California. The largest of the Channel Islands, Catalina has a fascinating geologic history and is rich in marine and lithic resources. It was was inhabited at least 9000 years BP by the people known today as the Island Tongva. The first documentation of Torqua occurred in the early 1970’s with the identification of 19 red pictographs, although by today’s standards this campaign was not sufficiently systematic. To date there is little to no characterization of the site’s physical history.

This paper presents the results of new imaging technologies based on Decorrelation Stretch and an assessment of local climatic conditions and substrate composition, which will lead to a better understanding of the site’s history and deterioration. Following an assessment of condition, the significance of the site to its stakeholders, including the indigenous population, the island’s contemporary residents and its landowners, will be investigated.

Decorrelation Stretch is a method of producing false color digital images that is able to reveal severely faded pigmented decorative surfaces, which has been used successfully here to identify previously unrecognizable and invisible pictographs. Photogrammetry will be performed to create a unified image of the site, which, at roughly 50’ long and on a hillside, has not been possible to present previously. X-Ray Diffraction has identified the pigment used and the composition of its substrate. Portable x-Ray fluorescence (XRF) spectroscopy and ultraviolet/visible/near infrared (UV/Vis/NIR) reflectance spectroscopy will be performed on-site to create a map of the panels’ surface composition for comparison with visual characteristics such as color variation, patterns of deterioration, presence of water from various sources, and accretions. Polarized light microscopy (PLM) will be performed on a thin-section slide of the host rock’s substrate for identification of its composite minerals. Environmental data loggers will be placed at the site to measure ambient temperature (T) and relative humidity (RH) at the site through daytime/nighttime cycles for a year to compliment spot measurements of rock surface temperature, T and RH that were collected in summer 2014.

This information will be used to characterize the degradation patterns of the bedrock panels that comprise this site, focusing on the interrelationship of the rock’s composition, local climate and water transfer through the rock and from external sources. An assessment of the site’s significant and the danger of anthropogenic impact will lead to recommendations concerning future management strategies and protection.

An Analysis of Unidentified Dark Materials Between Inlaid Motifs on Andean Wooden Queros: Preliminary Findings
Heather White

Paramount in the study of Andean civilizations, past and present, are the people’s rituals and ceremonial customs which have pervaded the Inka and post-Inka periods. These rituals mark social and religious occasions with offerings to the gods that ensure economic prosperity and good health. Decorated wooden cups, called qeros, have facilitated these customs through the centuries, witnessing long use-lives as they are passed down from generation to generation. As custodians of ancient Andean rituals and ways of life, contemporary Andeans use the cups as their ancestors did: to hold and transfer libations of blood or the fermented maize beer chicha, to honor, respect, and celebrate religious, social, and economic activities. It is from here that qeros enter museum collections, their use-life ends, and their preservation as vestiges of Andean culture and ritual begins. In recent years there have been technical studies of Andean qero technology focusing on the materials used for the polychrome inlay decoration, identified as an array of natural and manufactured pigments bound by an organic resin from species of the Elagaeia tree (E. utilis and E. pastoensis), locally known as mopa mopa. However, currently there is a lack of information concerning the dark material(s) present around the polychromy, which exhibits peculiar and substantial loss on vessels in many museum collections, sometimes as though it has been physically scraped off. For this study, different dark materials surrounding the polychrome design on a group of qeros belonging to the Fowler Museum at the University of California-Los Angeles were investigated in an effort to characterize them and potentially explain the technical, cultural, and/or ethnographic reasons for their presence and causes for their loss. Various documentation and analytical techniques were employed, including visual analysis, digital photography, UV-induced visible fluorescence, Reflectance Transformation Imaging (RTI), microscopy, portable X-Ray Fluorescence (pXRF) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and Gas Chromatography-Mass Spectrometry (GC-MS). Preliminary results have shown surface modification and ethnographic wear which appear related to the material’s loss. Identifying this material(s), understanding its origin and explaining its loss will contribute to our knowledge of the vessels’ manufacture and/or ethnographic history and use, and guide our transferred custodianship over such artifacts of Andean traditions.

Posters
Technical study of a miniature Tuareg camel saddle using X-radiography and X-ray fluorescence spectroscopy
Elizabeth Anne Burr

A miniature camel saddle from the Fowler Museum is an example of the dyed leather and metal work for which the Tuareg of Niger are known. This saddle made by Hamidan Oumba for the tourist market is a replica of traditional tamzak camel saddles used by the Tuareg elite. It was suggested by an African art scholar that a miniatures such as this would be constructed using the same materials and techniques as a traditional tamzak with a wooden frame. However, X-ray imaging revealed a substrate that included more dense materials in addition to wood. X-ray fluorescence spectroscopy (XRF) data was acquired from a number of locations over different substrate materials (as corresponding to x-ray images), and different types of dyed leather, which were overlaid for interpretation. Correlations were found between the dense substrate material and the trace elements rubidium and strontium used to identify clays. This and the texture seen in X-ray image suggest that clay based components of the frame were manufactures for this object, a deviation from a traditional construction. Also, the turquoise leather was found to be rich in chlorine, copper, and tin, suggesting the use of bronze chloride corrosion to create the leather pigmentation as is traditional among the Tuareg. These results suggest a combination of both innovation and tradition in the construction of this art piece.

Diagnostic Imaging Techniques for the Identification of Tortoise Shell
Lesley Day

The focus of this poster is the documentation of a specific patterning, found within and unique to tortoise shell, made up of random swirling lines, which most likely correspond to the yearly depositions of keratin that occur as the turtle grows. This phenomenon has been observed in passing in some literature, but has not been fully characterized and is little understood in any discipline. The patterning has been observed as topography in some antique tortoise shell samples, and also as darkened lines in an example that appears to have suffered light damage. This poster will illustrate how documentation techniques including UV-induced visible fluorescence and Reflectance Transformation Imaging (RTI) have proven to be extremely useful in observing and documenting the pattern, and how characterization and further understanding of the pattern can be used as a diagnostic criteria for distinguishing tortoise shell from imitative materials such as plastic and horn.

The documentation illustrated in this poster is one component of my master’s thesis research about light-induced alterations to tortoise shell, and specifically how light may induce alterations to the patterning described, such as darkening and increased visibility. For the study, two taxidermied hawksbill turtles (Iretmochelys imbracata) were generously donated by the US Fish and Wildlife Department of Forensics, and the scutes from one turtle carapace were removed for use as the sample material. The samples are currently undergoing accelerated light aging under three different parameters: exposures mimicking window lighting (which filters some UV), museum lighting (which filters nearly all UV) and a chamber emitting UVA radiation. An important outcome of this research will be a better understanding of photochemically induced alterations in tortoise shell, and preventive lighting guidelines for tortoise shell materials based on the findings of the light aging study.

Piecing together the history of an 18th century printed Armenian Prayer Scroll
Colette Khanaferov

The use of prayer scrolls along with other religious art and literature have for played a significant role in the Armenian culture since the 5th century. The scope of this study is to investigate the history and materials used on a printed, 18th century Armenian prayer scroll. This analysis involves the examination of the scroll with the use of non-destructive analytical photography, fiber optic ultraviolet-visible and near infrared reflectance spectroscopy, X-ray fluorescence and Raman spectromicroscopy. The study attempts to identify and characterize pigments, colorants, ink, and the paper used to construct the prayer scroll. The text along with the illustrations have been translated and studied in an attempt to provide an overall understanding of the scroll, printing techniques, religious significance, use, as well as the traditional practices in the Armenian culture in the 18th century.

Preliminary Research on Biocorrosion of Archaeological Glass
William Shelley

The scope of this research is to investigate the mechanisms and process of biologically induced corrosion of archaeological glass. Archaeological glass samples from Greece and Cyprus suspected to have undergone biocorrosion were analyzed to characterize the chemical composition, microstructure, and topography to determine the difference in the chemistry of the glass surface and the bulk. Analytical techniques included scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray fluorescence (XRF) spectroscopy. Modern glass samples were placed in petri dishes with sulfuric and oxalic acid to simulate potential corrosion from acids produced by microorganisms. This research aims to fill a gap in our knowledge on glass biocorrosion and to evaluate the effects of microorganism on archaeological glass.


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Preventive Conservation Education – Research Topics from the Course “Environmental Protection for Collections” (2014)

Faculty from North American conservation programs who are engaged in instructing graduate courses focusing on preventive conservation strategies for collections are sharing curricula, resources, and topics for student research for the first time. With support from the Getty Conservation Institute and a boost from Prof. Hannelore Roemich at the Conservation Center, Institute of Fine Arts, NYU, faculty and alums met in New York in November 2014 to lay the groundwork for these exchanges. The next meeting will take place just prior to the Association of North American Graduate Programs in Conservation annual meeting in April 2015.

Students in the UCLA/Getty Program in the Conservation of Archaeological and Ethnographic Materials, and students interested in collections stewardship from the Department of Information Studies and other fields, together enroll in a course entitled “Environmental Protection for Collections in Museums, Libraries and Archives.” This course involves students in a review of environmental and biological agents of collections deterioration including light, temperature, relative humidity, pollution, and insects and fungi. Students perform monitoring to identify agents and to gain an understanding of material sensitivities and protective methods available for collections. Of increasing significance within all types of collections are preventive, or passive, rather than interventive, or active, methods of preservation. Collections preservation measures are often designed to limit energy use and therefore also contribute to environmental sustainability. In this course, while research topics are proposed for a required paper, students are encouraged to pursue topics that align with their individual interests. What follows are abstracts of research papers completed by students enrolled in the “Environmental Protection for Collections” class during fall 2014.

Student research projects in preventive conservation from the art conservation programs at Queen’s University and the University of Delaware are also accessible. Research from students in other North American programs, as well as curricula and teaching resources, will eventually be made available online.

Map showing one of the spaces monitored in the course this fall (the archives processing room of UCLA's Biomedical Enigineering Libary) and the types and locations of environmental monitoring equipment deployed (map by Heather White)

Map showing one of the spaces monitored in the course this fall (the archives processing room of UCLA’s Biomedical Enigineering Libary) and the types and locations of environmental monitoring equipment deployed (map by Heather White)

Ellen Pearlstein
Associate Professor, Information Studies and the UCLA/Getty Program in the Conservation of Ethnographic and Archaeological Materials


Exhibition of Daylight Fluorescent Colorants
Betsy Burr

When exhibiting collection material, lighting environment must take into account both the fading properties of material and the lighting parameters required for visitors to read the material on display. This can pose a number of challenges when collection material includes fugitive dyes. When modern daylight fluorescent materials are present, there is an added challenge due to the instability of these molecules and the broad spectrum of light potentially required to fully observe their fluorescing properties.  This poses interesting questions regarding the exhibition environment of these pigments as UV filtration is a common method used to preserve material from fading during exhibition. This raises the question of whether UV filters have a noticeable impact on the readability of fluorescent pigments? What properties must be considered in the safe exhibition and storage of daylight fluorescent pigments?

Fluorescent colorants are found on virtually any substrate as dyes, inks, or pigments within a resin or lacquer, and either applied to the surface or mixed into the substrate as seen in plastics. Daylight fluorescent colorants are added to many products today and have been used within fine art since 1960s pop art movement.[1]  They are also found in modern ethnographic works, particularly laundry “bluing” brighteners applied as colorants to traditional materials.[2] These pigments can be found in collections, and as modern material continues to be accessioned into the future, conservators and museum professionals may find an increasing number of collections material including daylight fluorescent colorants.

 

A Brief Discussion of the Photographic Activity Test and its Relevance to Housing Paper Artifacts
Stella Castillo

The Photographic Activity Test (PAT) was developed by the Image Permanence Institute to explore the suitability of housing enclosures for photographic materials and is specifically a predictor of long-term interactions between enclosures and photographs.  The photographic activity test can be performed on paper or plastic and the results of the test indicate whether the enclosures contain harmful chemicals that will cause image fading or staining over time. The test consists of two components: a test to detect image fading resulting from harmful chemicals in enclosures and a test to detect staining reactions between enclosures and gelatin.   The photographic activity test is now an international standard, ISO18916:2007, and is highly regarded as a selling point by manufacturers of archival and storage products.  According to the Image Permanence Institute, the PAT will assist in the elimination of storage materials that may augment destructive consequences that might arise in a less than perfect storage environment.

 

Traditional methods used to enhance preventive protection of paper-based collections from fungal outbreaks
Lesley Day

One of the most dangerous and prevalent problems encountered in collections of paper-based materials is contamination by mold.  Due to the nutritive properties of cellulose for all fungal species, once an outbreak takes root, it can be difficult to contain.  Historically, chemical fungicides have been used in addition to other methods that can be very hazardous to workers due to their toxicity.  These methods are also increasingly known to be hazardous to the collections they are meant to protect, especially paper.  Fungal species are also known to become resistant to chemical fungicides through adaptation, so it is increasingly likely that they will eventually cease to be effective.[3]  An alternative that has started to gain interest in research for the integrated pest management of cultural heritage collections is the use of natural products derived from plant sources such as essential oils or extracts of their active ingredients, medicinal plants, and spices for use in preventive scenarios that also incorporate other measures such as environmental controls.  Research into their use for remedial treatments is also of interest, though so far it has been difficult to find effective applications that do not put objects at risk. This paper will review the research that has been conducted recently about integrating natural methods into pest management for fungal species, and will evaluate an anecdotal account of traditional Indian practices from an Indian conservator and how these methods might be tested for more widespread use in collections.  In addition to preventing harmful exposure to toxic chemicals for both workers and the collections, these methods could find potential applications for culturally sensitive collections that cannot be exposed to chemicals, anoxia, or other methods that would interfere with the cultural significance of the material.

 

Light Emitting Diodes for Libraries
Mitchell Erzinger

Light Emitting Diodes (LEDs) are semiconductor devices that use electrical currents to produce visible light in the form of photons. LED technology has been advancing in recent years, rapidly outgrowing the traditional incandescent and fluorescent light sources to be one of the most cost and energy efficient light sources on the market. This paper will first examine this research into the efficacy of LEDs, citing studies by the Getty Conservation Institute and the U.S. Department of Energy, and following will be a discussion, involving multiple case studies, of the potential benefits of incorporating LEDs into Library settings.

 

Sustainable Selection and the Costs of Light Sources
Kira Fluor-Scacchi

This paper will address the use of LEDs for exhibition lighting in two cooperative definitions of sustainability; the first is that which supports financial stability for an institution, while the second considers this technology as a component of a system which incorporates a social mentality, the physical equipment, and managerial techniques that encourage an environmentally-conscious preservation model. In order for cultural institutions, such as museums, to ensure their long-term sustainability, exhibition factors must be considered that ensure both the viability of the organization as well as the stewardship of significant objects. Museums house and care for these items, and in turn share them with the local community or a community of researchers who value their preservation and accessibility. Policies must be established to allow artworks and artifacts to be displayed in an environment that is suitable to be viewed by patrons while bearing the costs of their exhibition.

 

The Effects of Temperature and Relative Humidity on Digital Photographic Prints
Karen Karyadi

Since its inception in 1839, the field of photography has continued to evolve both aesthetically and technically. The past few years certainly have seen advancements at an exponential rate in this area, especially with the commercial availability of digital photography. Consequently, digitally printed photographs are increasingly becoming the normative output for photographers and artists working with photographic methods. As such, it is important for museums, archives, and libraries, together with the conservation and photographic communities, to be able to address concerns regarding the storage and display of digital prints as part of their role as cultural institutions. Indeed, technological developments in digital photography are taking place on a daily basis and will continue to do so into the foreseeable future—an ongoing shift that must also be anticipated and take into consideration. Nevertheless, this paper focuses on the effects of temperature and relative humidity on digital photographic prints, particularly within the context of cultural institutions.

 

Protecting museum objects from pest infestation and biological growth
Colette Khanaferov

As a visitor it may be hard to conceptualize external factors that can effect a museum’s collection. A museum’s responsibility for the object begins once the object has been acquired into the collection. Conservation of an object however is not limited within the walls of the conservation lab but needs to be considered throughout the entire museum space. Once in the museum, objects are susceptible to pest infestation, biological growth, and deterioration due to fluctuation of temperature and humidity. The scope of this paper is to discuss previous and current approaches taken to eradicate pest infestation and biological growth as well as introduce a potentially new and safer alternative. Chitosan is a naturally occurring polysaccharide that is produced from chitin and can be found in many organisms such as crab shells and shrimp. The use of the polymer includes applications in the food industry as antibacterial agents, in the pharmaceutical field for drug delivery systems as well as new medical advances. Chitin and chitosan can be useful in the conservation field for object preservation.

 

The Physical Implementations in Preserving Fashion Forecasting Reports
Alexander Kosztowny

Archivists, librarians, and historians desire to document, save, and preserve the past. Some ephemera, like newspapers, have an original intent that was not meant to last long periods of time, yet these items are kept and preserved to the best of archivists’ and preservationists’ abilities. One other such example is trend forecasting books and predictive reports. These books are used by the fashion industry to predict what silhouettes, colors, fabrics, and styles will be the most popular in upcoming seasons so designers, manufacturers, and retailers can successfully sell items that consumers want. There is a need to preserve these books in terms of their documenting costume history, popular and street culture, and how the fashion industry has evolved from an elusive, designer based industry to a global communication of style, technology, and individualism. There are many concerns when physically preserving these books that are not unique or unrelated to the preservation of other artifacts and books. However, due to the multimedia nature of trend forecasting reports, many considerations must be taken into account.

 

Illuminative Inhibition of Microbial Growth in Cave Art Systems
Tom McClintock

Several cave systems in France and Spain house some of the earliest known examples of painted surfaces in the world, and since their discovery have attracted major public interest and visitation. The environments of these caves are extreme, characterized by nearly total darkness, stable temperatures, high relative humidity and low amounts of organic nutrients. The organisms that are able to survive in these conditions are highly specialized, and the ecosystems they comprise are subsequently susceptible to change. In this regard, no development of hypogeal environments to accommodate tourism can be considered minor, although the obvious examples of excavation, construction of pathways (even elevators) and installation of air conditioning systems were common practice. When one considers that Lascaux, in Southern France, and Altamira, Spain, two of the most extraordinary cave art sites in the world, hosted respectively 1,800 and 3,000 people per day at the zenith of their visitation[4], [5], the irreversible effect on these delicate systems is hardly surprising. Both Lascaux and Altamira suffered the misfortune of being discovered before management, preservation and scientific communities with an enlightened understanding of these deleterious effects existed, and they must all now play catch up to mitigate the sites’ deterioration.

 

Making Change in Environmental Requirements for Museum Loan Policies
Hilary McCreery

Museum loan policies exist, in part, as a way for museums to ensure that the materials that are loaned out to other institutions will be cared for properly and will return in the same condition in which they departed. One important facet of museum loan policies is the set requirements for museum environments, which establish, among other specifications, explicit levels of temperature and relative humidity to be maintained by the borrowing institution. However, there are many differing perspectives on best practice for implementing standards for museum environments, many of which are based on historical research findings and experience. In fact, “over the past 100 years, both research and practice in the area of environmental standards for storage, loan, and exhibition of museum collections have produced rather bewildering results, from oversimplified formulas to complex, yet incomplete research findings” (American Institute of Conservation, n.p.). Currently, there continues to be much discussion in regards to the rigid parameters set for museum environments, especially in the context of loans, and some conservation and museum professionals have begun to call for a change toward not only more flexible environmental standards, but more transparency on the part of museums about their current practices. As a result, the International Institute for Conservation of Historic and Artistic Works (ICC) in collaboration with the International Council of Museums Committee for Conservation (ICOM-CC) recently released a declaration for new environmental guidelines, which promotes both transparency of and flexibility for environmental conditions in loans policies. While the tight parameters established for environmental conditions in loan requirements have historical roots, the debates taking place in the current landscape of museum policy have called for these new changes in international standards.

 

Bentley’s Medicinal Plants: A Recommendation for Exhibition
Katherine Monroe

Spices, Exotic Flavors & Medicines, a digital exhibition put on by the History Special Collections section of the Louise M.  Darling Biomedical Library at UCLA, incorporates digitized  images  of  the  four  volumes  of  Robert  Bentley  and  Henry  Trimen’s  Medicinal Plants; being descriptions with original figures of the principal plants employed in medicine and an account of the characters, properties, and uses of their parts and products of medicinal  value (hereafter  referred  to  as  Medicinal Plants).[6]  With such an interest in the Internet exhibition,  demand  for  a  twelve month  physical  exhibition  of  the  volumes  has  arisen, leading to an examination of the public reading room in which they are to be displayed, as  well as of the volumes themselves.  The results have led to the following observations and recommendations,  with  the  desire  to  successfully  exhibit  the  four  books  without compromising their preservation.

 

The Use of Experimental Lighting on Archaeological Sites to Prevent Microbial Growth
William Shelley

Microorganisms have the ability to affect archaeological sites not only aesthetically, by covering surfaces with different colored ‘patinas’, but also chemically by producing corrosive acids that attack surfaces.  Methods in the past to control and reduce the growth of microorganisms have included their removal mechanically and the use of biocides.  These techniques however are intended only to remove existing growth and will not prevent future growth.[7]  The use of biocides can be detrimental to archaeological sites if they are not completely rinsed away and leave residues on surfaces.  Biocides may also be toxic to the individual who applies the material, as well as to the environment.  Recently, new strategies to control the growth of biological activity on archaeological sites have been developed using specific wavelengths of light.  A brief overview of previous work on the subject and a discussion about their potential use follows.

 

Environmental Considerations for Alternative Building Materials Used in Museum Storage and Display
Heather White

The materials used for the storage and display of collections play a vital role in maintaining the condition of the collection. Experience has shown that more often than not, traditional building materials contain components that will off-gas harmful vapors, like volatile organic compounds (VOCs), which can initiate or accelerate degradation processes in susceptible cultural materials. Such reactions are promoted by their use and decomposition, especially when subjected to various indoor climate variables. The “indoor chemistry” of building products has been studied in depth, and accounts for reactions that happen during the production of the material whose products are released at the customer’s site, or synergetic reactions between different materials at the site once installed.[8],[9]

Alternative building materials like aluminum composite materials (ACM), entered the market addressing these concerns and offering an inert construction material safe for indoor environments and the collections held within them. However, the question arises: Can such materials so carefully manufactured to be lightweight, strong, weather resistant, water proof, heat resistant, fire resistant, formable, nitrogen/chlorine/sulfur-free, with low VOC emissions, also be safe for the environment at large in terms of their manufacture and disposal? Further, are corporations spearheading the fabrication of safe and archival exhibition cases, like The Small Corporation, maintaining environmentally conscious objectives in their manufacturing processes?

 

Footnotes
[1] Margaret Holben Ellis, Christopher W. McGlinchey, and Esther Chao, “Daylight Fluorescent Colors as Artistic Media,” in The Broad Spectrum (London: Archetype Publication Ltd, 2002), 160–67.

[2] Nancy N. Odegaard and Matthew F. Crawford, “Laundry Bluing as a Colorant in Ethnographic Objects,” in ICOM Committee for Conservation, 11th Triennial Meeting in Edinburgh, Scotland, 1-6 September 1996: Preprints (James & James (Science Publishers) Ltd., 1996), 634–38.

[3] Shaheen Fauzia. 1995. “Application of Kanja Seeds (Pongamia glabra vent) for the control of Museum Insects.” In Biodeterioration of Cultural Property 3: Proceedings of the 3rd International Conference on Biodeterioration of Cultural Property, July 4-7, 1995, Bangkok, Thailand, (Office of Archaeology and National Museums. Conservation Science Division, 1995), pp. 567-575.

[4] Bastian, Fabiola, et al. “Impact of biocide treatments on the bacterial communities of the Lascaux Cave.” Naturwissenschaften 96.7 (2009): 863-868.

[5] Schabereiter‐Gurtner, Claudia, et al. “Altamira cave Paleolithic paintings harbor partly unknown bacterial communities.” FEMS Microbiology Letters 211.1 (2002): 7-11.

[6] The digital exhibition can be accessed at http://unitproj.library.ucla.edu/biomed/spice/index.cfm; Robert Bentley and Henry Trimen, Medicinal Plants; being descriptions with original figures of the principal plant employed in medicine and an account of the characters, properties, and uses of their parts and products of medicinal value (London: J. & A. Churchill, 1880) .

[7] Koestler, R.J., Koestler, V.H., Charola, A.E., Nieto Fernandez, F.E. (Eds), 2003. Art,Biology and Conservation: Biodeterioration of Works of Art. The Metropolitan Museum of Art, New York.

[8] Uhde, E., and T. Salthammer. “Impact of reaction products from building materials and furnishings on indoor air quality—A review of recent advances in indoor chemistry.” Atmospheric Environment 41 (2007): 3111-3128.

[9] Satlhammer, Tunga. “Emissions of Volatile Organic Compounds from Products and Materials in Indoor Environments.” The Handbook of Environmental Chemistry 4, Part F (2004): 37-71.


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UCLA/Getty Program Welcomes Visiting Scholar Dr. Guofeng Wei

The UCLA/Getty Program welcome visiting scholar Dr. Guofeng Wei, who will be working with us through January 2016. Dr. Wei comes to us from the Department of History, Anhui University, China.  He received his Ph.D. in Scientific History and Archaeometry from the University of Science and Technology of China. His current research focuses on the recipes and crafts of historical lime mortars of China, as well as a study on the application of traditional stick rice-lime mortar in conservation of cultural relics.  More recently, he carried out research studying the trace element characteristics of copper prills in slag from Tangjidun sites of copper smelting dating back to the late Shang Dynasty (ca. 1300 BC) in Anhui Province.  In addition he is studying the casting technology of bronze vessels dating from the late Shang Dynasty to Spring and Autumn Period (ca. 1300BC – 470 BC) from Zongyang County.

Dr. Wei will be providing lectures for some of our programs courses, as well as conducting his own research while he’s here.  He is currently giving two lectures on ancient metallurgy and metal casting in the course Conservation Laboratory: Metals II  (CAEM 239).

Dr. Guofeng Wei


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RTI of Etruscan Bucchero Fragments at Poggio Colla

My first summer internship with the Mugello Valley Archaeological Project (MVAP) at Poggio Colla has wrapped up, and it was an incredible season with exceptional finds! Under the guidance of head conservator, Allison Lewis—a UCLA/Getty alum (‘08 )—and with the sponsorship of The Etruscan Foundation’s 2014 Conservation Fellowship, I was afforded the amazing opportunity to participate in this project, which has been underway for the last several decades. MVAP has significantly contributed to the study of ancient Etruria with their work at Poggio Colla, the site of a hilltop settlement and sanctuary that spanned the 7th-2nd centuries B.C.E.

A particularly groundbreaking find happened in 2011, when a student participating in the MVAP field school found a stamped bucchero fragment that appears to depict a woman in the midst of childbirth. This imagery is the earliest documented in Italy and nearly unparalleled in the ancient Mediterranean, however study of the finely recessed scene is difficult due to its small size and worn nature. It takes just the right angle of raking light to highlight the surfaces and make the scene legible (Fig. 1), which is often the case with these stamped and incised bucchero vessel fragments.

Fig.1. The birthing stamp (inv. PC 11-003), found on a bucchero fragment, measures just around a centimeter in height and is worn, requiring magnification and raking light to study its imagery. [Photos courtesy of Dr. Phil Perkins, The Open University].

Fig.1. The birthing stamp (inv. PC 11-003), found on a bucchero fragment, measures just around a centimeter in height and is worn, requiring magnification and raking light to study its imagery. [Photos courtesy of Dr. Phil Perkins, The Open University].

As an 2014 Etruscan Foundation Conservation Fellow, I proposed a special project to the Foundation involving the documentation of bucchero fragments using Reflectance Transformation Imaging (RTI), which Allison has wanted to test at Poggio Colla for several field seasons. This technique, created by Cultural Heritage Imaging (CHI), involves a low-cost, easy photographic set-up that can be macgyvered in the field with fairly basic supplies (Fig. 2). RTI essentially blends a series of photos of an object under different angles of light to create an interactive file (a polynomial texture map) that one then explores using a “virtual torch” in various rendering modes. In other words, instead of researchers straining their eyes and handling the object in different raking light or studying static images, they can explore the features and subtle details of the object’s surface in a single, high-resolution image with an adjustable light source that they can control.

Fig. 2. We were able to disassemble a standard desk lamp to become our movable light source, much to our excitement! This imaging technique was affectionately called “A Thousand Points of Light” amongst the staff, and it was pointed out that it’s quite a ritualistic process (appropriate for the sanctuary site) as we huddle on the floor around an ancient artifact with a single torch lighting us.

Fig. 2. We were able to disassemble a standard desk lamp to become our movable light source, much to our excitement! This imaging technique was affectionately called “A Thousand Points of Light” amongst the staff, and it was pointed out that it’s quite a ritualistic process (appropriate for the sanctuary site) as we huddle on the floor around an ancient artifact with a single torch lighting us.

Our set-up was simple. We picked a relatively closed-off room adjacent to the field conservation lab where we could have good control over ambient light; as you can see, it doesn’t have to be a special room-nor a room at all if you’re on-site! We used the lab’s point-and-shoot Canon G10 digital camera with a remote so as not to shake the camera when capturing the images, a copy stand, a disassembled desk lamp that we tethered to a string, and small, black reflectance spheres purchased by the conservator prior to the season (Fig. 2).

The black spheres are required in the frame near the object, in order to reflect the location of the light source for the software during image processing (Fig. 3). Any black, reflective sphere can be used; Allison purchased 1/4” and 7/16” silicon nitride (Si3N4) ceramic balls used for ball bearings (Boca Bearing Company), which we mounted in frame with Benchmark wax, at times stuck to bamboo skewers to be held level with the object’s surface. The string tied to the lamp was measured to roughly 4x the diameter of our object, becoming the fixed radius at which we moved the light around the object for each photo (Fig. 2).

Fig. 3. Items inserted in frame for image processing or posterity (such as the black spheres, grey scales, or labels) can be cropped out in the final stage of processing in RTIBuilder so that your final product is simply your subject, to be navigated and explored in RTIViewer.

Fig. 3. Items inserted in frame for image processing or posterity (such as the black spheres, grey scales, or labels) can be cropped out in the final stage of processing in RTIBuilder so that your final product is simply your subject, to be navigated and explored in RTIViewer.

Keeping the camera in a stationary position with our object and black spheres in focus, we proceeded to take around eighty images per object, with each object taking roughly fifteen minutes to shoot; one person snapped the photo while the other moved the light. We continued taking photos until we felt we covered a full “umbrella” of light around the object in our series of images.

The photos were then processed using the RTI software (RTIBuilder), which is available for free on CHI’s website, along with RTIViewer for navigating the final product. RTIBuilder can be finicky and particular, especially in naming files. No spaces, hashtags or other similar characters are acceptable in file names. We also found that the program did not recognize capitalized file extensions (for example not .JPEG files, only .jpeg) so if you can’t control which file type you’re capturing in on your camera, you’ll need a computer with Photoshop or an equivalent image processing software that can convert them. For optimal quality, CHI recommends capturing images in RAW and then converting to jpegs (RTIBuilder can only process jpeg files). Processing items inserted in frame (black spheres, gray scale, label, etc.) can be cropped out at the end before the images are converted into the single digital file, which can be interactively viewed by anyone who has downloaded the free RTIViewer (Figs. 3-5).

Fig. 4. When you open RTIViewer, you have several options at your disposal: you can control your light source; you can zoom in and out on your subject and move around over its surface; you can take a snapshot of your field of view (which saves as a .jpg and XMP file); and you can play with a diverse range of rendering modes available in the dropdown menu.

Fig. 4. When you open RTIViewer, you have several options at your disposal: you can control your light source; you can zoom in and out on your subject and move around over its surface; you can take a snapshot of your field of view (which saves as a .jpg and XMP file); and you can play with a diverse range of rendering modes available in the dropdown menu.

Fig. 5. The different rendering modes can emphasize or deemphasize particular surface characteristics, and some modes allow you to study the surface without the distraction of surface pigment/colors.

Fig. 5. The different rendering modes can emphasize or deemphasize particular surface characteristics, and some modes allow you to study the surface without the distraction of surface pigment/colors.

As you can see, this imaging technique offers a different, versatile way of studying the morphological and topographic features of an object’s surface, no matter how minute, without the need to access the object itself. Given the various rendering modes available in the RTIViewer, it can be used as a supplementary tool in examining the object, and it can also be offered as an alternative format for researchers wanting to study the piece, limiting unnecessary handling….which we conservators like to hear! We found RTI to be an especially useful field tool for recording and studying worn, stamped bucchero decoration, fabrication related marks on bucchero surfaces, and incised characters on ceramic and stone surfaces (Figs. 6-8). After a great pilot program, the MVAP conservation staff and other project members hope to continue exploring its potential applications at Poggio Colla in future seasons.

Fig. 6. An incised and stamped bucchero sherd (inv. PC 13-075).

Fig. 6. An incised and stamped bucchero sherd (inv. PC 13-075).

Fig. 7. A bucchero sherd (inv. PC 14-062) with reticulate burnishing, nearly invisible under even light (note the ‘Default’ image). Modes like ‘Normal Unsharp Masking’ can reveal the very subtle, recessed burnishing marks, and others like “Diffuse Gain’ can contrast them.

Fig. 7. A bucchero sherd (inv. PC 14-062) with reticulate burnishing, nearly invisible under even light (note the ‘Default’ image). Modes like ‘Normal Unsharp Masking’ can reveal the very subtle, recessed burnishing marks, and others like ‘Diffuse Gain’ can contrast them.

Fig. 8. An inscribed stone base (inv. PC 05-105).

Fig. 8. An inscribed stone base (inv. PC 05-105).

Heather White (’16)

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