UCLA/Getty Conservation Program

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


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Class of 2018 Summer Internships

The quarter is coming to an end and as our students are working to finish up object treatments and projects, they’re also getting ready to head out on their summer internships.  Here’s a list of the great places our students will be going to this summer:

We hope they enjoy their time at their internship sites and we look forward to hearing about the work they did when they come back this fall!


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Beantown or Bust – the 2016 ANAGPIC Conference

It’s that time of the year again….No, not when we sit back in LA enjoying the 85° weather and work on our tans, while the Midwest and Northeast deals with freezing temperatures and 1-3 inches of snow in April (too soon?)….But that time when students from North American conservation graduate programs gather for the annual ANAGPIC conference.

This year the conference is being hosted by the Straus Center for Conservation and Technical Studies, Harvard Art Museums and will take place April 14th-16th.  In addition to the great papers that will be presented highlighting student work from many conservation specialties, this year includes a poster lightning round.  The conference also coincides with the Joint Interim Meeting of ICOM-CC’s Scientific Research and Education and Training in Conservation Working Groups.  That meeting will be held at the same location, on April 13-14th, prior to the start of ANAGPIC .

This year we have a few presentations from UCLA/Getty students.  3rd year student Colette Badmagharian will present the results of her research on an Armenian prayer scroll that she conducted as part of their MA thesis project.  We also have two 1st year students, Marci Burton and Lindsay Ocal, who will be presenting in the lightning round session.  You can find presentation titles and abstracts below.

For more information on the ANAGPIC 2016 conference, to access the conference schedule or read the abstracts of the papers that will be presented, please visit site: http://harvardanagpic16.com/  Information about the ICOM-CC Joint Interim Meeting can be found here: http://icom-ccharvard.com/

Good luck to all those presenting and we hope all the students have a great time at this year’s ANAGPIC Conference!


 

Presentations
18th-century Armenian Prayer Scroll: The Study of Cultural Context and the Characterization of Manufacturing Techniques 
Colette Badmagharian
For centuries, prayer scrolls and illuminated Gospels have played a crucial role in Armenian history and culture. Relatively little is known about the materials and techniques used to construct such Armenian texts and potential risks for their survival. To bridge this gap in our knowledge, a severely damaged 18th-century Armenian prayer scroll was investigated, using a holistic and integrated approach that combined both cultural and historical context with scientific research. Selected texts and illustrations were translated and thoroughly examined with members of the Armenian community and further investigated with comparative examples from various institutions. This examination led to an appropriate preventive conservation measure that was taken to ensure the preservation of the fragile prayer scrolls.  Pigments, colorants, and ink, were characterized with the use of non-invasive and non-destructive techniques including analytical photography, ultraviolet, visible and near infrared (UV-Vis-NIR) fiber optic reflectance spectroscopy (FORS), X-ray fluorescence (XRF) and Raman spectromicroscopy (mRS). This study provided an overall understanding of the constituent materials, printing techniques, religious significance, use and function, as well as traditional practices of the Armenian culture in the 18th-century.
Poster Lightning Round
3D Computed Tomographic Analysis of a Pre-Columbian Chilean Child Mummy Bundle
Marci Burton
Analysis and Retreatment of an Archaeological Polychrome Ceramic Bowl from Amapa, Mexico
 Lindsay Ocal


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UCLA/Getty Program Welcomes Visiting Scholar Dr. Pujun Jin

The UCLA/Getty Conservation Program welcomes visiting scholar Dr. Pujun Jin, who will be with us through November 2016.  During his time here, he will be working Dr. David Scott examining ancient Chinese bronzes. Dr. Jin joins us from the School of Materials Science and Engineering, Shaanxi Normal 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 metallurgical examination of artifacts excavated from the site of Sanxidui dating to the Shang Dynasty.  He is also studying the lost-wax technique used to cast a bronze mou (cooking vessel) from the Ba Culture and the corrosion and conservation of ancient Chinese plated bronzes.

Pujun Jin


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UCLA/Getty Program Welcomes Mellon Fellow in Conservation Education Laleña Vellanoweth

The UCLA/Getty Program is pleased to welcome Laleña Vellanoweth as the Andrew W. Mellon Fellow in Conservation Education for the 2015-16 academic year.

Laleña is a Costume and Textile Conservator. She received her B.S. in Biochemistry and B.A. in Art from California State University, Los Angeles and her M.A. in Art History and Certificate in Conservation from the Institute of Fine Arts at New York University. She has worked at the Costume Institute at the Metropolitan Museum of Art, the Museum of Modern Art, the Autry National Center, and Los Angeles County Museum of Art.

As part of her Mellon Fellowship, she will be researching diversity in art conservation and surveying parallel diversity programs for other museum fields. She will also be working on a research project on Californio costume, focusing on a technical study of three charro suits from the early nineteenth century, one of which was worn by Don Vincente Lugo, a member of one of the founding families of Los Angeles. Laleña will also give lectures on textiles and costume, including fiber identification and costume mounting.

IMG_2394


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Welcome Class of 2018!

Today we welcomed the start of fall (despite the warm LA weather), and the new incoming class of the UCLA/Getty Program!

The class of 2018 will begin their first day of instruction tomorrow with a course focusing on documentation and imaging techniques.  They’ll also have the opportunity to take classes this quarter that cover the technology and deterioration of ceramics and glass, principles and ethics in conservation, and science fundamentals in conservation. Two of their courses include object-based projects where they will examine, document and assess the condition of a group of pre-Columbian ceramics from the collection of the Fowler Museum at UCLA.  Between their course and lab work, it looks like we will be keeping them pretty busy this quarter!

We wish the class of 2018 good luck with their coursework and lots of success in the conservation program!

From L to R: Marci Burton, Lindsay Ocal, Hayley Monroe, Michaela Paulson, Morgan Burgess, Mari Hagemeyer

The class of 2018! From L to R: Marci Burton, Lindsay Ocal, Hayley Monroe, Michaela Paulson, Morgan Burgess, Mari Hagemeyer


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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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