Caroline (Carrie) Roberts presented an interesting talk about a multi-year collaborative project that demonstrates the real impact that surveys and technical studies can have on collections. In less than two years, the authors were able to survey a collection of 200 limestone stelae, assign treatment priorities, identify the agents of deterioration, suggest environmental guidelines, carry out treatments, and develop an informed treatment protocol.
The project began with the survey of the collection of limestone stelae by then 3rd year intern LeeAnn Barnes Gordon and continued as part of Carrie Roberts’ fellowship project at the Kelsey Museum. LeeAnn and Carrie collaborated with scientists in analytical laboratories at the University of Michigan and at the Detroit institute of Arts, including co-author Cathy Selvius DeRoo. Through their hard work and successful collaborations, the authors were able to accomplish an impressive amount and significantly improve the condition and long-term preservation of this invaluable collection.
Carrie first introduced the history of this collection of funerary stelae excavated in 1935 from the Roman-Egyptian site of Terenouthis. You can find some of this info on the Kelsey website here… and here:
She then spoke about the condition issues identified during the survey, which included stone delamination, surface powdering, biological staining, and peeling, darkened coatings. There were several types of salt efflorescence present including spiky salt crystals and more round gypsum like-salts. Spot tests identified chlorides and sulfates. Interestingly, research conducted into the archival holdings of the museum produced some incredibly relevant information regarding the past treatment of the pieces. A transcribed 1941 lecture by the archaeologist indicated that Duco cement was used to stabilize the stelae as they were excavated. The presence of cellulose nitrate was later confirmed using FTIR on samples of the darkened and peeling coatings.
As a result of the survey, approximately ¼ of the collection was determined to be high priority for treatment. These stelae received further study to characterize the deterioration and identify a treatment protocol. Testing was carried out using a barrage of analytical techniques including FTIR, XRF, XRD, specimen culturing and DNA analysis. The results allowed identification of soluble salts (calclacite- a calcium chloride acetate salt produced from interactions with offgasing materials + halide salts), characterization of stone properties (clay component within limestone- possibly responsible for delamination), and ID of the biological growth (black staining identified by DNA as Epicoccum nigrum of the class dothideomycetes, lichen not identified- no DNA present).
The treatment protocol that was developed through testing included:
-Consolidation of the limestone with CaLoSil (150nm particles of lime hydrate Ca(OH)2) in n-propanol. Testing was conducted using CaLoSil, Paraloid B-72, and Conservare (Ethyl silicate) consolidants. CaLoSil was most successful as it reduced powdering after 1 application without darkening stone. It is presumed to penetrate deep into the stone due to the small (nano) particle size.
-Structural stabilization using Paraloid B-72 (in 85:15 ethanol/acetone) injected into delaminating cracks. Not many of the stelae had extensive delamination but Paraloid B-72 was found to successfully stabilize cracks and areas beginning to delaminate.
-Desalination by poulticing with Arbocel paper pulp. This method was considered challenging/problematic and so the environmental controls were considered the best method of preventing future problems from soluble salts
-Coating reduction was accomplished by applying acetone followed by blotting.
-Biological staining was reduced by swabbing with ethanol; however, this was not found to be fully effective.
-Environmental parameters were set based on the equilibrium RH of the identified salts. The recommendation was to stay below 75% humidity, which is the equilibrium of halide salt and below that of calclacite (79%).
Carrie finished with some questions for future research, including: how is the CaLoSil distributed in the limestone after consolidation? What is the nature of the clay component in the limestone? What are the possibilities for reduction of the biological staining? And what is the best method for treating the stelae that had been stabilized with cyclododecane in 2009 when the collection was relocated to the current storage area.
Overall a very informative talk that hopefully will inspire similar in-depth survey and treatment projects!
Author: Ainslie Harrison
39th Annual Meeting – Objects Morning Session, June 3, ” The Alaska Fur ID Project ” by Ellen Carrlee and Lauren Horelick
For the final talk in the Friday OSG morning session, Ellen Carrlee, conservator at the Alaska State Museum in Juneau, presented on the Alaska fur ID project, an online resource created by herself and conservation fellow Lauren Horelick (and partially funded by the FAIC Carolyn Rose Take a Chance grant) to aid in the identification of fur on both historic and Alaskan Native objects. This easily accessible fur ID website, posted in blog format (www.alaskafurid.wordpress.com), presents a wealth of diagnostic information on nearly 50 Alaskan animal species including hoofed animals, rodents, hares, canines, felines, bears, weasels, and marine mammals. Ellen and Lauren gathered information from the fur ID literature and combined it with their own observations from visual and microscopic examination of a wide range of animal hairs. A variety of hair types from each animal were examined and documented as they can range greatly in characteristics. Guard hairs and underfur, for example, are quite different from each other, as are the hairs from different parts of the animal (e.g. from belly as opposed to legs). On the other hand, they found that the sex, age, and season in which the fur was gathered had little impact on the micro-diagnostic features of the individual hairs. All of this information is available not only in text form in each entry on the website, but also in annotated photomicrographs and photographs of the animals in JPEG format that can easily be saved and used in your own reports and documentation. In addition, each entry includes the scientific name of the animal, the micro qualities of the hairs (shape, medulla size, medullary index, scale pattern, cross-section shape), macro qualities (color, banding, etc.), cultural uses, and information on how to differentiate the hair from similar animals (“troubleshooting”). Helpful tips for preparing slides included using Duco cement for scale casts and a cross-sectioning technique using artificial cork with a sewing machine needle.
While the Alaska Fur ID project was inspired by the Czech Furskin website (http://www.furskin.cz/), which presents diagnostic information on skin and fur together with SEM images, the Alaska Fur ID website is specifically tailored to aid those using primarily transmitted or polarized light microscopy to identify the sources of individual animal hairs. As someone who works with a collection that includes Alaskan fur objects, I believe this website will be extremely useful, and I hope that it will be a model for others interested in expanding the online resources for fur identification worldwide.