Results & Discussion
The synthesis of nano-particles of calcium hydroxide is a process that requires special equipment and technique. However, with training and the proper laboratory equipment and technique this process can be done in conservation laboratories. The application of nano-particles of calcium hydroxide to cordage has a number of difficulties to consider: (1) penetration of the particles into the interior of the fiber matrix; (2) ensuring a uniform distribution of particles in the matrix; (3) application of a carrier solvent to the matrix must allow for good transfer of particles and not negatively impact the structure of the matrix (by swelling, contracting, or chemically reacting). The evaluation of particle penetration into the matrix may be addressed by measuring the pH of the surface of cordage fibers located near the center of the ply.
The application of carrier solvents to the matrix was addressed by testing a variety of solvents on the matrix and observing changes in the shape of the cordage and changes in the matrix on a chemical level (i.e. measuring pH change). A concern with using non aqueous solvents is the possibility that the solvent may remove bound water and alter structural flexibility. Isopropyl alcohol as a carrier solvent is promising.
The artificial aging study and accelerated aging studies were designed, conducted and gave useful results. The tensile strength data indicates a significant reduction in loss of tensile strength for the treated samples. The data in the artificial aging study using a shake table indicates a difference in loss between the treated and untreated samples; suggests a positive effect of calcium hydroxide nano-particles on archaeological cordage, but the differences are not statistically significant. The artificial aging study using a shake table does identifies the impact of different container types on the cordage’s long-term structural stability.
This project has examined the applicability of Ca(OH)2 nano-particles for the treatment of degraded semi-processed cordage from archaeological sites. The treatment has previously found success with cellulosic substrates such as paper and wood. During this project several types of cordage samples were collected, prepared, tested, artificially aged, treated, and evaluated. The project and the data it produced have provided a large volume of information as a basis for further studies. The project has successfully identified reproducible and inexpensive methodology for both treating cordage samples and testing the success of the treatment. Based on our experiments, the use of Ca(OH)2 nano-particles in isopropyl alcohol solvent is a promising conservation treatment for degraded cordage.