Heritage Science Branch: Research Projects
These projects support the strategic themes and goals of the current Heritage Science Research Strategy.
Strategic Theme 1: Managing Risks and Building Resilience
Evaluating Building Performance
Lead: Mark Ormsby, Physicist
Over the past 15 years NARA has cut energy consumption by 50% and reduced greenhouse gas emissions by 30% at its Archives II facility, College Park, Maryland. At the same time, a model of deterioration rates indicates that improved storage environments have slowed the aging rate of the records by 30-50%. These outcomes were achieved as a result of a collaborative project between NARA Preservation Programs heritage scientists, NARA facility staff and building engineers. The project was informed by recent environmental management research and explored energy savings through systematic shutdowns of HVAC systems coupled with pollutant filtration testing to monitor any increase in pollutant levels. Similar evaluations will be carried out at other NARA facilities to optimize environmental management operations for improved environmental performance and storage environments.
Characterization of Thermal Recording Media (ThermofaxTM): 1950-1970
Leads: Dr. Henry Duan, Chemist, Lisa Isbell, Senior Conservator
Thermal recording media dating from the 1950s – 1970s, including ThermofaxTM, may be inherently unstable. Understanding the inherent properties of these media from different generations of manufacture is necessary to predict the rates at which they will change, determine the leading causes of media degradation and suggest risk mitigation strategies to prevent irretrievable losses of information. These questions will be investigated by analyzing the image forming chemistry, acidity levels of the paper support, media configuration, and the response to different types of selected conservation treatments. Light sensitivity will also be assessed using micro-fading technology. The results of this investigation will facilitate the development and optimization of preservation and conservation protocols for NARA holdings on thermography media including when reformatting the record to preserve content is recommended.
Strategic Theme 2: Integrating Research into Policy and Practice
Investigating the Materiality of the Charters of Freedom: Exploiting the Potential of Proteomic Analysis
Leads: Dr. Jennifer Herrmann, Chemist, Mark Ormsby, Physicist
This project will investigate proteomic analysis techniques to determine the substrates used for the Charters of Freedom. When the Charters were extensively examined in 2003, miniscule parchment samples were collected and analyzed. Developments in proteomic methods since then may allow the same samples to be used to determine the source and possibly the species of the animal skin. This information will help to answer frequent questions about how the Charters were made.
The data gathered from this study will be useful for scholars who are beginning to exploit proteomic analysis, as well as inspiring further innovative approaches to analyzing and preserving NARA’s holdings.
Technical Analysis of Ansel Adams Photographs
Leads: Dr. Jennifer Herrmann, Chemist, Sara Shpargel, Photograph Conservator
Included in NARA’s vast photographic holdings are some 200 images created by the renowned American photographer Ansel Adams. This project will use advanced non-destructive techniques to investigate the materials and techniques Adams used while employed by the US Government Department of Interior to photograph the National Parks, Indian Reservations, and related sites.
XRF instrumentation will determine the elemental composition, while a fiber optic FTIR probe will establish the presence of coatings and the level of gelatin degradation if present. The collected data will be compared to other published descriptions of Adams’ printing techniques and will help to inform preservation of these records.
Investigating Causes of Differences in Cold Extraction pH Test Results from Corrugated Paperboards Between the Pulp and Standard TAPPI Methods
Lead: Dr. Henry Duan, Chemist
A comparative study between the pulp method and TAPPI’s cold extraction method to determine pH and alkaline reserve in different types of paper products was undertaken in 2013. The study found that the cold extraction pHs obtained from the pulp method for corrugated paperboard materials were consistently lower than that from the TAPPI standard protocol, by an average of -0.5 pH units. The key difference between corrugated materials and other papers is the adhesive used in the production of corrugated boards. The adhesive could be released into the solution during the pulp processing preparation and is the suspected cause of the lower pH readings. This study will test this hypothesis. The outcomes will inform the selection of quality assurance protocols and material standards.
Strategic Theme 3: Adopting, Adapting and Implementing
Evaluation of Cellulose Nanofibril Sponges for Removal of Rubber-Based Pressure Sensitive Tapes
Leads: Mark Ormsby, Physicist, Prof. P. McGuiggen, Johns Hopkins University, Materials Science Department, Dr. Natalie Lavoine, North Carolina State University, Department of Forest Biomaterials, Elissa O’Loughlin, Conservator.
While cellulose fibers are used to manufacture paper, cellulose nanofibers are much smaller and unusually light, strong, and absorbent. Their unique properties are being applied in numerous fields, including new products to aid in recovery from oil spills. In collaboration with researchers and conservators, this project will build on published research and explore how nanofibril ‘sponges’ can be adopted and adapted for use in conservation treatments. These sponges have the potential to hold a large quantity of non-polar solvents, which can then be carefully dispensed to effectively reduce or remove rubber-based pressure sensitive tape repairs present in many paper-based collections.
Paper Conservation Applications of Volatile Silicone Solvents
Leads: Dr. Jennifer Herrmann, Chemist, Beatriz Centeno-Pineiro, Senior Conservator
Cyclomethicones are a family of compounds with low viscosity and high volatility that are incorporated into many products. The two most often referenced in conservation literature are referred to as D4 and D5. Because of their hydrophobic properties, they should protect water-sensitive media during conservation wet treatments. Their high volatility makes them attractive for this purpose since they will sublime from the record after wet treatment without having to be removed physically or by using another solvent. A few studies have examined general properties and behavior of D4/D5 in paper conservation treatments.
For this research, quantitative data will be collected to investigate fundamental interactions between the silicone solvents and a variety of papers in order to inform conservation treatment decisions. A key question is how long it takes the D4/D5 to sublimate completely from a variety of papers.
Assessing the Feasibility of Developing an Early-Warning Tool for Mold Detection on Cultural Heritage Materials
Leads: Dr. Henry Duan, Chemist, Prof. Ralph Mitchell, School of Engineering and Applied Sciences, Harvard University
This ‘proof of concept’ project will assess the efficacy and practical application of a mold detection assay system developed by the Applied Microbiology Laboratory, Harvard University in archives. Paper records and other types of cultural heritage are susceptible to biodeterioration from mold, especially in humid climates and after flooding emergencies if water infiltrates. Conditions that support mold growth are expected to increase in the future due to climate instability. While preventive measures can mitigate the risk of mold growth, techniques for early detection of mold spores remain elusive. If the assessment results are promising, this mold detection technology could be developed as an early-warning system of mold spores that might damage heritage culture.
Platinum Palladium Photographic Ghost Image Research Project
NARA conservators and conservation scientists investigated a ‘ghostly’ phenomenon that occurs in some of NARA’s photographic prints. Images that contain platinum or palladium metal can create detailed mirror images of the original image, called a ghost, on adjacent paper as a result of direct contact with the photograph. Platinum and palladium photographs are considered to be among the most permanent photographs, yet the common ghost image suggests that some reaction between the metal nanoparticles and cellulose, or cellulose degradation products, occurs during aging. An accelerated aging procedure was developed that successfully created ghost images in the laboratory – this is believed to be the first time ghosts were formed in the lab. Historic photographs with historic ghosts and induced ghosts on historic non-collection photographs, as well as modern platinum photographs of various known recipes and processing conditions were studied to investigate the mechanism of the ghost image phenomenon. Analytical techniques (FTIR, XRF, XPS, SEM, TOF-SIMS, DART) were explored in collaboration with scientists at neighboring institutions and other government agencies. The NARA team presented their preliminary findings on this topic at the Platinum and Palladium Photography Symposium hosted by the Foundation of the America Institute for Conservation in collaboration with the Smithsonian National Museum of the American Indian, National Gallery of Art, Library of Congress, and the Smithsonian National Museum of American History. This research was published in Platinum and Palladium Photographs: Technical History, Connoisseurship and Preservation. ed. C. McCabe, American Institute for Conservation (2017).
Heat and Solvent Set Repair Tissues
For decades, pre-coated heat and solvent set tissues have been the preferred method for mending certain types of library and archival materials due to their translucency and ability to be used without introducing moisture. In recent years, the commercial adhesives long used to make these tissues became unavailable. The National Archives and Library of Congress conducted a multi-year, interagency collaboration to research new heat and solvent set repair tissues for mending paper-based records.
The tested adhesives included Lascaux 498 HV, Lascaux 303 HV, Avanse MV-100, Plextol B500, Aquazol 200 and Aquazol 500. Tissues prepared with these adhesives were applied to paper and silver-based photographic substrates using both solvent and heat set methods. The samples were analyzed for color change, reversibility after artificial aging, and ‘blocking’ after natural aging and under pressure. The findings showed that the method of application - heat or solvent - did not affect aging or testing results. The color of the Avanse/Plextol adhesive tissues changed during testing. Several of the Lascaux 498 HV and Lascaux 303 HV dilutions passed testing, and the Aquazol 200 and 500 tissues also passed testing.
The joint work was published in the Journal of the American Institute for Conservation.
Non-Destructive Analysis of 14th-19th Century European Handmade Papers
Non-destructive analysis of 1,578 paper specimens (14th-19th century) was undertaken to better understand changes in paper composition over time and how these variations affect paper stability during natural ageing. Gelatin content and color were determined using UV/Vis/NIR spectrometry. Residual metals were measured using XRF. The analyzed components included potassium and sulfur as elements indicative of alum concentration; iron as a typical paper contaminant; and calcium, which is often associated with compounds such as calcium carbonate used as alkaline reserves.
The research demonstrated that papers lighter in color (closer to white) are associated with higher levels of gelatin and calcium, and lower levels of iron. The study also showed significant decreases in gelatin and calcium concentration over time, with the largest differences coinciding with the rise of printing around 1500. The drop in pH of paper over the centuries, observed by many in the research community, is explained by the decreases in these two components rather than by a rise in alum concentration, which remained fairly stable. The research showed that better quality paper that aged well was associated with higher gelatin and calcium concentrations and color closer to white. Poorer quality papers that aged more rapidly were associated with higher iron levels and greater thickness. This work was published in Restaurator.