Case Study: Flying Squirrel Treatment

Another of the specimens treated as part of our preparation for our Care of Historic Mammalian Taxidermy workshop at the Society for the Preservation of Natural History Collections (SPNHC) 2017 annual meeting was a taxidermy giant red flying squirrel. Project Intern Logan Kursh executed the treatment.

TearRepairProcess

Conservation Intern Logan Kursh performing conservation treatment on a flying squirrel taxidermy mount. ©AMNH /F. Ritchie

There was little data available about the date or location where this specimen was collected, or about the taxidermist who prepared it. However, an examination of the specimen indicated that it was likely a nineteenth century mount, prepared using the binding method.

The specimen suffered from a number of structural and aesthetic issues. The treatment of many of these condition issues is detailed in a poster titled, “Strategies for the Conservation and Storage of Taxidermy:  Flying Squirrel Case Study” that was prepared for the SPNHC 2017 annual meeting in June 2017. Access the poster here:

SPNHC_2017_Squirrel Poster_Logan Kursh

The poster did not address the restoration of the squirrel’s snout, however, so that work is explained below.


Skin on the face and around the squirrel’s snout is thin and delicate. Like all skin in taxidermy, this hairless skin dried out and discolored after death. Taxidermists typically address this with the use of “finishing materials” such as wax and paint to add vitality. The finishing materials degrade over time, giving the specimen an unnatural appearance.

flying squirrel before treatment

Flying squirrel before treatment. Note the desiccated deformed nose. ©AMNH /L. Kursh

In the case of the squirrel, the nose appeared flat and desiccated. The skin had discolored, and there appeared to be some local fur loss. Examination of other giant red flying squirrels in our collection and reference images of squirrels in life confirmed that the specimen’s appearance was not an accurate reflection of the species in life. With the approval of the Mammalogy Department, we decided to craft a reversible overlay for the squirrel’s snout from reference images using well-understood conservation materials.

The nose and upper lips of the specimen were restored using an overlay made from Paraloid F-10 bulked with glass microballoons. Paraloid F-10 is a thermoplastic acrylic resin. It was chosen for this application because it adheres well to wax and has known ageing properties. The Paraloid F-10 mixture was spread onto a piece of silicone-release Mylar and toned slightly with dry pigment, then shaped with a microspatula based on reference images. The overlay was allowed to dry for several hours and reshaped as it slumped.

flying squirrel during treatment

Flying squirrel during treatment. The white fill material has been applied on top of the original surface and shaped to reconstruct the nose. ©AMNH /L. Kursh

To ensure complete reversibility, the overlay was attached to the specimen over a barrier layer of Paraloid B72 in acetone. Paraloid B72 is a stable thermoplastic acrylic resin and is a common art conservation adhesive in many different applications. Minor adjustments to the shape of the overlay were made, and the overlay was allowed to dry overnight. Once dry, further adjustments to the shape were made with a scalpel in consultation with expertise from the Mammalogy Department.

flying squirrel during treatment

Flying squirrel during treatment. The nose has been reconstructed and the white fill material toned brown with paint. The next step is to add hairs to integrate the fill with surrounding areas. ©AMNH /L. Kursh

flying squirrel during treatment

Flying squirrel during the final treatment step – the addition of hair on the toned fill of the nose. ©AMNH /L. Kursh

The overlay was toned with acrylic paint based on available references. Rabbit fur was flocked onto the overlay with Lascaux 498HV. Lascaux 498HV is a thermoplastic acrylic resin that dries flexible and is reversible with heat.

After treatment the squirrel’s nose appears more life-like and integrates with surrounding features.

flying squirrel after treatment

Flying squirrel after treatment. Note the reconstructed nose. ©AMNH /L. Kursh

For details about other aspects of the treatment of this specimen, be sure to check out the SPNHC poster. SPNHC_2017_Squirrel Poster_Logan Kursh

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Case Study: Lemur Mount Treatment Part 1: Condition Examination

In addition to testing the stability of metal-complex dyes, we have been studying condition issues facing historic taxidermy collections (see our previous posts on the Mammalogy condition survey) and performing conservation treatments on selected specimens. These treatments stabilized important mounts and served as case studies for a workshop on the Care of Historic Mammalian Taxidermy at the 2017 Denver meeting of the Society for the Preservation of Natural History Collections (SPNHC).

Before Treatment of lemur.

Before treatment of lemur taxidermy mount. ©AMNH /C. Richeson

In one of these Case Studies, project intern Caitlin Richeson treated a damaged red-fronted brown lemur (Eulemur rufus) taxidermy mount. Its catalog number suggests that it was acquired soon after the Museum was formed in the late 19th century. This post and the next one will provide some of the details of that treatment.

All conservation treatments should begin with thorough documentation: an object description, condition examination, and photography. Caitlin’s project provides a good example of what that documentation may look like for a piece of taxidermy.


Object Identification: A full-body taxidermy mount of a female red-dronted lemur (Eulemur rufus) mounted on a habitat base constructed from a tree branch.

 

Description
The specimen is constructed around a composite manikin that is visible in several locations due to previous damages. The manikin is composed of wood wool (thin wood shavings traditionally made of poplar, pine, or spruce) bound to recreate the musculature form of the specimen; cotton batting used to bulk appendages such as the hands; and a metal armature used to provide rigid structural support. Appendages such as the hands and feet still contain original skeletal materials. The nose, snout, and eyelids are shaped from a soft black material, likely a pigmented wax.

The specimen is attached to the base with ferrous metal wires at three points: the proper right palm, the proper right foot, and the proper left foot. The wires penetrate the palm and feet of the specimen as well as the habitat base where they have been secured to the base by bending at a 90-degree angle.  The specimen is mounted in a standing position gripping the habitat base with the proper right (PR) hand and both feet.

There is a paper specimen label tied to the proper right ankle, which contains taxonomic information in two separate campaigns of writing. There is also a metal plate attached to the habitat base located on the front of the branch.  The plate is inscribed with the catalogue number and attached to the branch with two tacks. There is another metal tag tied with a thin metal wire around the PR wrist of the specimen, also stamped with the catalog number.

Condition
The specimen is in fair condition. It is structurally stable; however, there are two detached elements, several areas of fur loss, tears and cracks/splits in the hide, which contribute to the overall instability of the specimen. In addition, the specimen is covered in a layer of light grey dust and grime.

Hide/Manikin:

  • A portion of the proper left (PL) hand is detached from the specimen. The detached hand consists of the hide and four digits, but excludes the thumb, which remains attached to the specimen. The detached hand has several cracks/splits in the hide and a large loss on the palm side, exposing the interior construction. The PL ear of the specimen is also detached and there are small areas of unrecovered loss.

Before Treatment of lemur detached proper left hand.

Before Treatment of lemur detached proper left hand.

Before treatment of lemur taxidermy mount. Proper left detached hand. ©AMNH /C. Richeson

  • On the lower back at both the PR and PL sides there several moderately large stable tears in the skin of the lower torso, which expose the wood wool manikin below. There is also a minor split located at the PR side of the vent. Although the skin is slightly out of plane, it remains somewhat pliable and can be pressed back into place with gentle pressure.
  • There is a small circular area of abrasion on the back of the PR hand.

Finishing Materials:

  • The material used to finish the nose of the specimen has sustained localized losses and a dent on the PL side. The eyelids, which are made from the same finishing material, have also been deformed.
    Before Treatment of lemur. Detail of nose with missing wax.

    Before treatment of lemur taxidermy mount. Note the loss of finishing material on the nose and the loss of skin on the ear. ©AMNH /C. Richeson

    Before Treatment of lemur. Detail of nose with missing wax.

    Before treatment of lemur taxidermy mount. Note the loss of finishing material on the nose. ©AMNH /C. Richeson

Fur:

  • The fur of the specimen has discolored to a light yellow-brown color, having lost its natural variation in red, brown, and black colors that are representative of the species.
  • There are several areas of fur loss located on the mount. The first is a a substantial loss of fur on the chin and underside of the snout. This species is identifiable by its characteristic “beard”, and thus the fur loss in this area detracts from the accurate representation of the species. There are also small losses associated with the detached PL hand and at the coccyx.
  • There are also beige accretions on the fur, primarily located along the seam at the center of the torso, and an overall layer of moderate dust accumulation on the fur.

Display Base (branch):

  • The specimen is well-secured to the tree branch habitat base, which appears to be in good condition. When examined in ultraviolet light, the base fluoresced a milky yellow/green color, and appears to have been coated.

After completing this type of photographic and written documentation, the conservator then submits a proposed treatment to the Collections Manager and/or Curator for approval. Follow along with the progress of this treatment in the next post.

 

 

Dyed Fur Samples: Part 1

The first phase of our lightfastness testing aimed to establish the lightfastness of the Orasol® and similar Sorasolve metal-complex solvent dyes in isolation‒ that is, in the absence of a binder, and without a chemically active substrate that could potentially influence the behavior of the dyes or interfere with the measurement of color change. (See earlier posts to explain the project plan and selected dyes. Future posts will explain the results of this testing, which is currently underway.)

The second phase of testing uses accelerated aging and periodic color measurements to look at how lightfastness is affected when Orasol dyes are applied to aged, faded furs as they are used in a recoloring treatment. We expect to see substrate impacts on lightfastness for several reasons:

  • As furs age, they produce reaction products that may affect the chemical behavior of an applied dye.
  • Compared to quartz, dyes deposit very differently onto hair. There is also significant variation among fresh and aged fiber surfaces, and among fibers from different animals.
  • The optical properties of dyed fibers differ from those of dye films on quartz. Differences in how the sample reflects and/or absorbs incident light affects its total light exposure dose and its apparent color.

Fur Selection

Several considerations played an important role in our selection of animal fur substrates. First, we sought furs that are light in color. The principle reason for this was that a light-colored substrate was needed to control our dye application and keep reflectance spectra minima in the range of 30–40 percent (see earlier post for reflectance discussion). For consistency of samples, the furs also needed to be as uniform in color as possible. To facilitate sample mounting, longer fibers were preferred over short. The fibers themselves should present minimal color change upon exposure to accelerated aging, ensuring that the dye (and not the fiber) is the primary contributor to any color change observed in a dyed fiber. Finally, we aimed to represent some of the naturally occurring variation in mammal furs, from hollow guard hairs and bristles to awns and underfur.

arctic fox skin

Arctic fox skin used for research samples.  AMNH/F. Ritchie

We ultimately chose furs from two animals with naturally white coats: an arctic fox and a white-tailed deer. The latter is fully white but not a true albino, a variation selectively bred to be whiter than the closely related “spotted” piebald. The arctic fox represents fine, smooth-haired fur-bearing mammals, while the deer offers hollow guard hairs.

However, there is an important downside to using white furs such as these. As we pointed out in our discussion of backing materials for our samples on quartz, light-colored substrates reflect and scatter proportionately more light than dark ones. Transparent dye films applied to highly light-scattering substrates will be exposed twice: once directly by the lamps, and a second time by reflected light from below, increasing the light-exposure dose. While faded historic taxidermy may be light in color, most examples are generally still darker than these bright white furs.

deer hide

White-tailed deer hide used for research samples.  AMNH/F. Ritchie

Consequently, light-scattering plays a larger role in the fading of our samples than is expected in the treatment that we are modeling. While it could be argued that our samples represent a worst-case scenario with respect to the impact of specimen color on the longevity of recoloring treatment, we acknowledge that the use of white furs is a compromise needed to consistently produce the most light-sensitive dye application possible.

Tanning

The impact of different tanning methods on the dyes under investigation is unknown and offers an interesting avenue for further research, but this is not addressed as part of our current project. Nevertheless, in order that they more closely model taxidermy in the American Museum of Natural History collection, the fox and deer pelts for this project were tanned according to methods representative of those historically used at the Museum.

leathers

Scraps of leathers prepared using different techniques and finishes. The type of tan can affect the condition of a taxidermy mount overtime.  AMNH/F. Ritchie

When considering the production and acquisition of historical taxidermy at the Museum, particularly for use in dioramas, the period of interest spans from approximately 1925 to 1965. Though we do not have a complete understanding of all the tanning methods in use at, and for, the Museum during this 40-year time frame, we were able to partner with a local tanner trained by Sinclair Clark, a renowned tanner who was on staff at the Museum around 1924–1927. Clark later set up tanneries in other locations, but maintained his relationship with the Museum tannery over a long period of time.

In general terms, Clark’s method involves the following:

  • The skin is salted to remove moisture and stabilize it prior to tanning
  • Tanning begins with rehydration in a saltwater bath until the skin is soft and pliable
  • It is next soaked in an acid pickle until swollen, and then shaved down on a fleshing machine or by hand
  • The skin is returned to the pickle, and, if needed, shaved again
  • The skin is then removed from the pickle and the acid is neutralized
  • Warmed oil is applied either by hand or with a “kicking” machine
  • The skin is left to sit overnight or for one day before being tumbled in hardwood sawdust until dry and soft
deer hide cross section

Cross section of the white-tailed deer hide used for the research samples.  AMNH/F. Ritchie

The upcoming Part 2 post will describe how we are mounting the furs to run as research samples.

Accelerated Aging Chamber, Part 2

Troubleshooting

Conservation Intern, Associate Conservator, and Project Conservator working to troubleshoot an issue with the water purification system that occurred while this post was written. AMNH/F. Ritchie

Part 1 of our posts on accelerated aging instrumentation introduced the Q-SUN Xe-3 accelerated aging chamber. In this posting we describe some of the challenges we have experienced in installing and operating the machine; challenges which were unexpected and eye-opening. Problem-solving these situations has been such an important learning experience for us, demonstrating what taking on a project of this magnitude really entails.

Modifying the Lab

Our initial challenge was retrofitting the lab to accommodate the needs of the unit. In addition to electrical and plumbing adjustments to provide sufficient voltage, surge protection, purified water, and condensate drainage (all while retaining the ability to move the unit around the lab on its casters as needed), we had to install a ventilation hood over the machine with a fan and ductwork to vent its exhaust directly out of the building. This was necessary to limit the machine’s impact on the environment in the lab and adjacent offices, which otherwise became uncomfortably hot and cold respectively. The improved ventilation also allows the machine to cool itself much more efficiently, reducing both the noise and overall consumption of purified water – saving both our budget and our ears. We learned firsthand how important it is to moderate lab temperature when the HVAC system in the lab randomly failed and the machine was forced to stop because the chamber air rose to an unacceptable temperature. Luckily our maintenance staff provided the troubleshooting for this situation and the test cycle resumed within 24 hours.

Lesson: Make sure to understand completely the needs of a machine and its impact on day-today processes.

IMG_20151104_115246043

Ventilation hood and fan installed above the Q-SUN Xe 3 chamber to extract heat generated from the machine, helping maintain lab temperature. AMNH/F. Ritchie

IMG_20151104_115259244

New ductwork installed to direct exhaust from the Q-SUN out of the lab. AMNH/F. Ritchie

Setting Test Parameters

Our next unexpected hurdle was in setting our testing parameters inside the Q-SUN (i.e. the RH, chamber air temperature, and irradiance). Our previous dye testing was undertaken following the ASTM D4303 (Method C) testing standard in a chamber that did not have the capacity to control for RH. Because our Q-SUN Xe-3 chamber can be run with RH control, we initially chose a different standard ASTM D4303 (Method D). Immediately, to our horror, we found that condensation was forming inside of the machine, dripping onto the carefully prepared samples and making them unusable.

Initial troubleshooting with Q-Lab Corporation (the Q-SUN manufacturer) focused on possible problems with sensors or calibration within the machine, but that did not solve the condensation problem. Ultimately we learned that the D4303 test Method D is outside the capabilities of the Q-SUN Xe-3 (and apparently outside the capabilities of any humidity controlled xenon arc testing chamber). This was not an intuitive conclusion since Method D is specifically written for a Humidity Controlled Xenon Arc Device. As such, we have adjusted our test parameters so that they now lie well within the capabilities of the machine, and more closely replicate the Museum’s diorama conditions that we are chiefly concerned with.

Lesson: Understand that standards are often simply guidelines to follow to provide consistent parameters for comparison. Standards can (and often, should) be adapted to meet necessary requirements.

Dealing with Malfunctions

The most recent wrinkle in our operation of this machine was the spontaneous cracking of one of the UV-blocking filters that we are using for half of the testing rounds. Though this required us to suspend our testing for a few days, Q-Lab Corporation was very quick in providing a replacement, and since then we have been able to run the unit without incident.

cracked filter with arrow

Crack in a portion of the glass UV filter. AMNH/F. Ritchie

Lesson: Be flexible and ready to deal with unforeseen circumstances, and maintain a good relationship with the manufacturer of your equipment.

Budgeting for Consumables

The Q-SUN Xe-3 requires air filters, water purification filters, replacement lamps, sample preparation supplies, and many other expendable items that add cost beyond the initial purchase of the machine. Our grant budget has been adequate to deal with consumable materials, but we have realized that we must be prudent when running the machine and we must stay on top of ordering replacement supplies. There are even differences between test cycles. We are finding that our UV-filtered test cycles use up the lamps and water filters more quickly than the UV-rich test cycles.

Lesson: Pad your budget for expendable supplies and be sure to order the next set of replacements as soon as you install the first set.

IMG_20151104_115333353

Row of Q-SUN replacement lamps awaiting installation. AMNH/F. Ritchie

IMG_20150902_145310932_HDR

Project Conservator replacing a lamp. AMNH/J. Sybalsky

CONCLUSION

Owning and operating an accelerated aging chamber, at least one as complex as the Q-SUN Xe-3, is more than a plug-and-play operation. We hope that the steepest part of the learning curve is now behind us, but past experiences have taught us to expect that new issues will present themselves as we continue to work with this machine.

Lesson: When using any new tool or taking on any new experimental analysis, be sure to build time into the project timeline for troubleshooting.

Special Post – Updated Team Taxidermy

Our blog posting took a short respite over the past few months, as we said a fond farewell and welcomed new members to our original Team Taxidermy.

Ersang_Ma

Associate conservator Julia Sybalsky presents a Certificate of Recognition to conservation pre-program intern Ersang Ma for her hard work during this project. AMNH/D. Finnin

It was bittersweet to say goodbye and good luck to our pre-program intern Ersang Ma, who has been working with the team since summer 2014.  Ersang was an essential troubleshooter, tireless preparer of samples, and diligent manager of data.  To honor her work, Ersang was awarded an American Museum of Natural History (AMNH) Volunteer Appreciation Award at a recent Museum reception.  Ersang leaves the project to attend the Winterthur/University of Delaware Program in Art Conservation this fall.

 

The former associate conservator for the Natural Science Collections Conservation (NSCC) lab and the In Their True Colors project blog writer extraordinaire, Beth Nunan, left the Museum to pursue new conservation opportunities.  Thank you for all of your hard work and organization, Beth!

 

Former project conservator Julia Sybalsky moved into the associate conservator role for the NSCC lab.  Julia began working in the conservation lab as a graduate student intern in 2010, continued as graduate fellow, and subsequently became the project conservator.  In addition to her new duties as associate conservator for the NSCC lab, she will continue work on this project to interpret data, carry out investigations at the Yale University Institute for the Preservation of Cultural Heritage, and provide troubleshooting support.

 

Lemur 2

Project Conservator Fran Ritchie (left). AMNH/E. Ma

The Team welcomed new project conservator Fran Ritchie in the spring.  Fran was a previous pre-program intern in the NSCC lab (2009-2010) and has continued pursuing experiences conserving natural science collections.  Now that Fran has joined the project, she carries out analysis at AMNH and is responsible for much of the dissemination of project findings.  This dissemination will culminate in a Care & Conservation of Taxidermy workshop to be held at an upcoming Society for the Preservation of Natural History Collections (SPNHC) conference at the conclusion of the project (2017).  Exact details will be announced in future posts.

 

In the fall the Project will welcome Caitlin Richeson as our new pre-program intern.  Caitlin will assist with sample preparation, data interpretation, and workshop organization. It will be an exciting time as data continues to accumulate and the workshop begins to take shape.

 

Upcoming blog posts will get back to the project information, including how we were able to troubleshoot our new Q-SUN Xenon Test Chamber to collect our first few rounds of sample data!