- The laboratory at the Arizona State Museum Conservation lab was equipped for the project.
- A synthesis of nano-particles of calcium hydroxide was successful and the process was sustainable.
- All cordage samples used in testing were registered and photographed. These include:
- Ethnographic cordage samples purchased from indigenous crafts persons
- Archaeological cordage samples from the Arizona State Museum.
- Replica cordage samples created using traditional methods and materials.
- A research design and various experimental protocols were developed based on research, trials, and the experience of team members.
- Aged paper samples were treated with nano-particles of calcium hydroxide (aqueous) to replicate the success of the technique as reported.
- Scanning Electron Microscopy was used to study and image the nano-particles in paper.
- An image processing macro was created to characterize physical properties of the calcium hydroxide nano-particles
- Cordage samples were treated with nano-particles of calcium hydroxide, both in aqueous and isopropyl dispersions.
- Solvent studies were conducted on Ethnographic cordage samples to evaluate swelling, drying rates.
- Ethnographic cordage samples (treated and untreated) were subjected to Tensile-Strength Tests; to Accelerated Aging using elevated temperature; and to Artificial Aging using a shake table.
- Archaeological cordage samples were subjected to Artificial Aging using a shake table.
- Fourier Transform Infrared Spectroscopy was used to confirm the chemical identity of the calcium hydroxide particles after synthesis.
- Cold extraction pH measurements were conducted on the Archaeological and Ethnographic cordage samples before and after treatment with nano-particles. It was also used before and after Accelerated Aging on the Ethnographic cordage samples.
- Comparative analyses, charts, and graphs for the data and results of this project have been gathered for preparation of presentations and a peer-review publication.
- A presentation was made at the AIC Annual Meeting in Milwaukee 2010.
- An abstract has been submitted for review to the 2011 North American Textile Conservation Society meeting in Oaxaca, Mexico.
- A presentation has been accepted for the College of Engineering spring 2011 seminar series.
The Arizona State Museum (ASM) at the University of Arizona in Tucson, Arizona is home to over 22,000 cataloged archaeological basketry, textiles and cordage objects. In previous years, the collection has been organized intellectually into a database and re-housed in acid-free paper trays in museum cabinetry. However, they continue to be threatened by their inherent fragility due to physical, chemical, and biological weakness. The Conservation laboratory sought to investigate a treatment method to further preserve the collection.
Cordage and basketry making in the Southwest is an ongoing tradition that spans over 10,000 years in the archaeological record. Cordage is the term used for any type of rope or string made by twisting fibers together. The fibers are usually referred to as hard or leaf fibers, soft or bast fibers, or seed fibers. Surviving fragments of archaeological cordage in museum collections are typically desiccated, brittle, tangled, shedding, and weak due in part to their low pH.
These conditions are well known in paper-based collections and the use of calcium hydroxide nano-particles, Ca(OH) 2, as a basic buffering system has been proven effective as a conservation treatment in paper (Giorgi 2002, Giorgi 2005) and wood (Giorgi 2009). The intent of this project was to evaluate the impact and effectiveness of this method as a treatment on archaeological cordage. However, utilizing calcium hydroxide nano-particles on cordage samples poses unique challenges that are not encountered with paper particularly due to the difference in processing.
The major goals of this project involved: laboratory set-up; synthesis of Ca(OH) 2 nano- particles; cordage sample acquisition; development of a research design; preliminary testing of solutions and solvents; mechanical and aging studies; analytical characterization; imaging and data collection; and report preparation. The project has demonstrated that aqueous dispersions of calcium hydroxide nano-particles are not an appropriate treatment for archaeological cordage because the cordage swells when treated with water. The study has shown that 2-propanol as a carrier solvent for Calcium hydroxide nano-particles does not swell cordage fibers or inhibit the migration of nano-particles into the matrix, while increasing the pH of the cordage. The results of this funded project suggest that calcium hydroxide nano-particle solutions in isopropyl alcohol is promising as a conservation treatment for archaeological cordage. This study has also confirms that storage that offers the most confinement and immobilization will further reduce damage from handling.
Grant Number: MT-2210-09-NC-06
Project Title: Evaluation of Ca(OH)2 Nano-Particle Treatment of Cordage/Basketry Organizational Name: University of Arizona, Arizona State Museum
Principal Investigator: Nancy Odegaard, PhD Project Team: Nancy Odegaard, Werner Zimmt, Molly McGath
Contact Information: 1013 E. University Blvd., P.O. Box 210026 Tucson, AZ 85721-0026
Phone: 520-621-6314 Fax: 520-621-297
Date: December 23, 2010 Revised: January 6, 2011