TECHNICAL
BULLETIN
‘Eyes’ on peacock tail feathers are a marvel to behold. They captivate and draw us towards each dark teal-pupil like center embraced by three larger concentric circles reminiscent of sapphire, bronze, and emerald gemstones.
Throughout history, eyespots have been featured in various cultures at different periods as counterposing symbols—good and evil, death and resurrection, and of course, pride and vanity
[1]
. Early Christians decorated catacombs with peacock feathers because they believed that “peacocks’ feathers did not fade or lose their shiny lustre…a sign of immortality or resurrection” [2]
. The use of peacock feathers as a decorative motif in Western visual culture became popularized in the 19th and 20th centuries with Symbolist, Aesthetic and Art Nouveau movements and became a “Peacock Fashion Fad”
[3]
. Peacock feathers from these periods are often parts of composite objects such as hats, fans, jewellery and gowns. Gloria Swanson once famously wore a lavish headdress of peacock feathers in a silent film, Male and Female (1919) [4]
. Yet, despite their bewitching beauty, the peacock tail feathers are delicate and fragile.They are challenging to store, display and conserve in the museums’ collections.They are also subject to fracture and subsequent loss in their eyespot detail, mostly due to mishandling, insect infestation and increased brittleness over time.
This article focuses on the stabilization of the peacock feathers in collections. It will not discuss the possible reconstruction of any missing portion. The goal is to arrest the original materials’ susceptibility to deterioration by improving their structural stability. The treatment involves the use of Paraloid™ B-72 as an acrylic “thread” to support the misshapen, bent or broken areas. It was originally proposed by France Rémillard, a conservator of ethnographic materials at the Centre de conservation du Québec, QC, Canada and further developed at the Musée de quai Branly, Paris, France
[5]
. The technique of using an acrylic thread as a splint is mostly available in French speaking publications that focus on treatment of ethnographic objects. It is hoped that the treatment method will reach a wide audience interested, or working, in the field of conservation.
Before starting the treatment, it is important to understand the peacock tail feathers as a material. The peacock tail feathers’ structure and their common causes of physical damage will be outlined. Reasons for using Paraloid™ B-72 will also be elaborated. Finally, the preparation and procedure of the treatment will be discussed in detail. Seven peacock feathers adorning a headdress will be used as an example. The headdress was kindly provided by the Conservation Department at the Museum of Anthropology at the University of British Columbia, Vancouver, BC, Canada.
FIGURE 1 . Peacock Feathers, Comparison of before (left) and after (right) the wet-cleaning
Peacock Characteristics | General
Feathers are composed of keratin, a structural protein. Keratin self-assembles into bundles of numerous fibers that further join to form a tough, insoluble structure. It is considered to be one of the strongest non-mineralized tissues found in nature
[6]
. Each feather has a central shaft called ranchis that runs the entire length. From the ranchis’ sides, parallel rows of barbs branch out. Barbules further extend from each barb ridge and interconnect with their tiny hooks to form the vane, giving the feather its overall shape. Each feather has a central shaft called ranchis that runs the entire length. From the ranchis’ sides, parallel rows of barbs branch out. Barbules further extend from each barb ridge and interconnect with their tiny hooks to form the vane, giving the feather its overall shape. Most birds have two types of tail feathers: flight feathers and tail coverts. Peacock tail feathers are of the latter; as tail coverts, they do not provide stability during flight but cover and protect the tail regions. Still, they are unique amongst birds as the longest and most brilliantly colored tail coverts in nature. Peacock feathers are also singular in that they have unusual barbule structure
[7]
. Each barbule differs in length and structural arrangement (e.g. spacing and overlapping pattern) to reflect visible light at varying wavelengths; their iridescence does not arise due to pigmentation [8]
. Peacock Characteristics | Classification
Peacock tail coverts can be divided into three groups, depending on structure and location: eye feathers, T-feathers, and sword feathers
[9]
. Not all tail coverts display eyespots. Eye feathers are the most defining feature of a peacock; they are the ones with “eyespots.” T-feathers are the longest tail feathers that surround the eye feathers. Both eye and T-feathers have widely-spaced barbs through the shaft, and their ranchis terminate with closely spaced barbs. However, instead of forming an eyespot, the barbs on T-feathers gather to form a semicircular T-shape at the end. The third and last group of the tail feathers are sword feathers. They are the “curved” feathers that frame eye and T-feathers at their borders. Unlike eye and T-feathers, their ranchis are curved like a scimitar, a sabre with a curved blade. Barbs are present unevenly on the ranchis; they tend to be longer and more concentrated on one side. Sometimes, though rare, sword feathers can develop eyespots
[10]
.Peacock Characteristics | Physical Damage
Peacock tail coverts are chemically stable. However, their delicate structure mean that they are prone to physical damage. In museum collections, peacock feathers are often fastened to the objects by adhesives or stitches; in some cases, their ranchis are bent, punctured, or wrapped around another material. These structural modifications make the feathers weak; the feathers are already under compression or misshapen, so they are more susceptible to breaking when subjected to additional stress, such as in handling
[11]
. The seven peacock tail feathers from the headdress at the Museum of Anthropology at University of British Columbia, Vancouver, BC, Canada well exemplify the treatment performed. Five eye feathers’ ranchis were fractured at the areas where they were wrapped tightly around cardboard cut-outs with copper wires. Two ranchis were further misshapen from frequent use. The curator wanted the peacock feathers to be realigned and stabilized in their original positions as they were the essential feature of the headdress.
Treatment | Preparation of a Paraloid™ B-72 Thread
To prepare a thread from Paraloid™ B-72, it is recommended to use solid pellets. A Paraloid™ B-72 pellet can be briefly softened with a source of heat for three to five seconds and stretched on either end into a thread with fingers or tweezers before it cools (fig. 2). A heat gun was used to reach the resin’s glass transition temperature of 104oF (40oC); glass transition occurs when the material turns from a rigid glassy state to a soft but not melted state. If using tweezers, it is recommended to use those made of metal, not plastic; plastic tweezers may melt with heating and potentially contaminate Paraloid™ B-72.
Due to its thermoplastic and stable nature, a Paraloid™ B-72 thread can be manipulated to be thinner, straightened, or curved with additional heating. The key point is that the acrylic thread has to be long enough to extend from two stable areas of the feathers and thick enough to support the feather’s ranchis to prevent it from returning to the previously misshapen, bent or broken position. Practice may be needed to achieve the thread of desired length and thickness.
FIGURE 2 . During treatment image of the cleaning process demonstrating the reduction of the tarnished silver
Paraloid™ B-72 | Use in the Field of Art Conservation
Paraloid™ B-72 is a clear acrylic resin widely used in the field of art conservation as a consolidant, coating and adhesive. Its versatile use is due to its stable, non-yellowing and good aging properties. Also, Paraloid™ B-72 is commercially available. The resin is supplied by Rohms & Haas Company in two forms: as solid pellets soluble in acetone, toluene, and xylene or solubilized in toluene.
Paraloid™ B-72 | Thermoplastic Polymer
As an ethyl-methacrylate copolymer, Paraloid™ B-72 is considered thermoplastic, that is, softening when heated and hardening when cooled. Paraloid™ can be heated and cooled several times with minimal changes in its chemical and mechanical properties; it remains flexible and tolerates stress-and-strain well on most materials. The resin is theoretically stable for 100 years of use
[12]
. This is Paraloid™ B-72’s unique thermoplastic stability of which the treatment takes advantage.Stabilizing Peacock Tail Feathers with an Acrylic Thread
SALLY GUNHEE KIM | Post-graduate Fellow in Objects Conservation
ART CONSERVATOR
DIGITAL
Treatment | Cleaning and Realigning the Feathers
Prior to applying Paraloid™ B-72 thread, it is recommended to minimize presence of ingrained frass (insect accretions), dirt and dust in the feathers to avoid further damage by pest and deterioration. It can be difficult to safely remove soiling from the feathers’ delicate structure as any attempt at cleaning will introduce additional stress. There are two ways: dry- and wet-cleaning methods.
The dry-cleaning method is a less invasive option; it involves the use of a soft bristled brush to gently sweep loosely bound frass, dirt and dust towards a vacuum nozzle at low suction. It is recommended to cover the nozzle with a nylon or polyethylene gauze and to vacuum along the direction of the vane to avoid disentangling the barbs and barbules. Even at lowest suction, some loss and disruptions in barbs and barbules may occur
[13]
. In most cases, dry-cleaning alone is enough to minimize the soiling. However, some dirt and dust may remain stubborn. Aqueous cleaning is not recommended. Prolonged soaking in water may result in breaking down the feathers’ chemical structure despite the insolubility of keratin in water, dilute acids and most organic solvents [14]
.
If necessary, distilled water at room temperature can be selectively applied on the distorted areas with a clean brush; the feathers will have to be promptly dried with a cool air blower to minimize swelling of keratin that may disrupt the feathers’ structure (fig. 1
). Another option is to immerse the feathers in industrialized methylated spirits (IMS) or white spirit [15]
. The advantage of using IMS and white spirit over distilled water is that they will not swell keratin. However, IMS and white spirit may remove naturally deposited fat and oil from the feathers and lead to discoloration [16]
.In cases where the feathers’ ranchis remain stubborn, they can be gently humidified via Gore-Tex® textile with warm distilled water to relax and manipulate the distorted ranchis into their original positions; the ranchis are held in place between two blotter papers with two paper clips for approximately ten minutes. Longer contact with water is inadvisable as it may lead to discoloration, mold growth or hydrolytic decay.
Treatment | Application of a Paraloid™ B-72 Thread
To use a Paraloid™ B-72 thread as a splint, it is gently but firmly held against the ranchis’ one side with tweezers. Paraloid™ B-72 is clear but may impart medium-to-high gloss, so it is suggested to place the thread to the ranchis’ back to be less visually distracting. Once secured, the acrylic thread is then activated with a drop of acetone with a clean brush or micropipette in at least three areas where the thread and the ranchis are in contact. By activating, it means dissolving a Paraloid™ B-72 thread’s surface to help the solubilized portion adhere to the ranchis. Preferably, drops of the solvent are applied close to or around the area of the ranchis needing support and at the thread’s ends which extend to the feather’s stable areas (fig. 3). The thread can also be activated with toluene, xylene, or Cyclo Sol® 53 to increase the open working time; however, they are slow-evaporating so they will take longer time to dry to the touch than acetone. Lastly, gentle pressure should be applied where acetone was applied between the thread and ranchis for at least ten seconds. The thicker the thread is, the longer it may take to adhere to the ranchis. If the treatment fails, the thread can be detached from the feather with acetone to remove points of adhesion from the ranchis and be re-activated.
FIGURE 3 . Comparison of before (left) and after (right) the application of a Paraloid™ B-72 thread
Conclusion
The appeal of using a Paraloid™ B-72 thread as a splint for feathers arises due to the resin’s stable and thermoplastic properties. There are ongoing studies to improve the technique. Some propose substitution of other materials, for example, Paraloid™ B-44, as threads, while others hope to find a way to use Paraloid™ B-72 without solvents for activation because they are concerned that acetone may lead to stiffening of the feathers.
The possibilities to improve the stability of feathers remain open, but it is hoped that with this article, fellow conservators will have another alternative to stabilizing feathers and perhaps other materials with fine structures (e.g. baleen and insect legs) in their collections.
Acknowledgement
I would like to express my special thanks of gratitude to Heidi Swierenga, Senior Conservator and Head of the Collections Care and Access Department at the Museum of Anthropology at the University of British Columbia, Vancouver, BC, Canada, for granting me permission to use the images and to write on the topic of the feather treatment. I would also like to thank Charmian Bursill, my lifelong mentor, for providing me helpful feedback.
REFERENCES
[1]
Warren-Chadd, Rachel, and Marianne Taylor. Birds: Myth, Lore & Legend. New York, NY: Bloomsbury Publishing Plc, 2016.
[2] Webster, Richard. The Encyclopedia of Superstitions. Carlsbad, CA: Hay House, 2009.
[3] “Peacock Fad.” Buffalo Center Tribune vol.13, no.33, sec. Fashion, December 8, 1905. Winnebago County, IA: Buffalo Center.
[4] Faris, Gerald. “From the Archives: Gloria Swanson, Queen of Movies’ Golden Years, Dies.” Los Angeles Times, April 5, 1983.
Accessible at:
https://www.latimes.com/local/obituaries/la-me-gloria-swanson-19830405-story.html
[5] Legrand-Longin, Stéphanie, Gabrielle Tiêu, Stéphanie Elarbi, and Michèle Dejean. “La conservation-restauration des plumes : une nouvelle technique de consolidation,” in Musée Du Quai Branly Technè no23 (2006) : 61–64.
[6] Zhang, Zheng, Ophir Ortiz, Ritu Goyal, and Joachim Kohn. “Chapter 23 – Biodegradable Polymers,” in Principles of Tissue Engineering, 4th ed., edited by Robert Lanza, Robert Langer, and Joseph Vacanti, 441 – 473. Cambridge, MA: Academic Press Books, 2014
[7] Burgess, S. C. “The physical structure, optical mechanics and aesthetics of the peacock tail feathers,” in Design and Nature: Comparing Design in Nature with Science and Engineering, edited by C.A. Brebbia and L. J. Sucharov, 435 – 443. Southampton, UK: WIT Press, 2002.
[8] Zi, Jian, Xindi Yu, Yizhou Li, Xinhua Hu, Chun Xu, Xingjun Wang, Xiaohan Liu, and Rongtang Fu. “Coloration Strategies in Peacock Feathers.” PNAS 100, no. 22 (October 28, 2003): 12576–78. accessible at: https://doi.org/10.1073/pnas.2133313100
.
[9] Mishra, Monalisa. “Structural Variations in Feather Morphology and Its Predicted Function in Indian Peacock (Pavo Cristatus).” American Research Journal of Biosciences 111.
[10] ibid.
[11] Dignard, Carole, and Janet Mason. “Caring for Feathers, Quills, Horn and Other Keratinous Materials.” In Preventive conservation guidelines for collections, 2018. accessible at: https://www.canada.ca/en/conservation-institute/services/preventive-conservation/guidelines-collections/feathers-quills-horn-keratinous-materials.html
[12] Feller, R.L. “Standards in the evaluation of thermoplastic resins.” In Preprints of the 5th Triennial Meeting of the ICOM Committee for Conservation, Zagreb, 1–8 October 1978. Paris, France: International Council of Museums.
[13] Schaeuffelhut, Stephanie, Helene Tello, and Simone Schneider. “Cleaning of feathers from the Ethnological Museum, Berlin,” in The Conservation of Fur, Feather and Skin, edited by Margot M. Wright, 62 – 68. London, UK: Archetype Publications Ltd., 2002.
[14] ibid.
[15] Rae, Allyson, and Barbara Wills. “Love a duck: the conservation of feathered skins,” in The Conservation of Fur, Feather and Skin, edited by Margot M. Wright, 43 – 61. London, UK: Archetype Publications Ltd., 2002.
[16] ibid.
