Artificial Aging of Paper-based cores wrapped in various isolating layers for use as archival storage supports, by Amy Baker Williams and Catherine H. Stephens
Abstract: In this study, the effect of artificially aging paper rolled onto support cores wrapped with isolating materials was examined. Oversized paper artifacts often cannot be stored flat due to their size. Therefore, these artifacts may be rolled onto a paper-based support core, which itself is wrapped with a barrier material, for use as a space-saving and long-term archival storage solution. A paper-based support core is made up of a series of paper sheets spiral wound onto one other and bound with an adhesive. Two of the cores chosen for this study were identified as being archival, implying a paper artifact can be rolled directly onto the core for long-term storage without detrimental effect. While both support cores were manufactured with paper that complied with the archival standards outlined by the Library of Congress, one core was bound using sodium silicate while the other was made using a proprietary blend of polyvinyl alcohol (PVOH) and polyvinyl acetate (PVA). The second two cores were identified as being non-archival. However, they were included in this study as they are occasionally used by conservation professionals. One support core was comprised of kraft paper and an unknown adhesive (supplier not able to identify) while the other consisted of recycled paper and a PVA/acrylic based adhesive. Five isolating layer materials were selected: a polyethylene non-woven film (PE), a multilayered film comprised of polyethylene, aluminum foil, and nylon, a polyethylene terephthalate film (PET), a heavy duty aluminum foil, and a tissue paper containing 3.5% calcium carbonate buffer. The effect of no barrier coating was also examined. Whatman no. 1 cotton paper (W1) was chosen as the model archival paper to be rolled onto each of the 24 support cores. Magnets were used to hold the W1 paper and isolating layer in contact with the cores during artificial aging. Tubes were artificially aged at 90°C and 50% relative humidity (RH) for up to 24 weeks and sampled at various time points. Changes to the yellowness index (YI) and pH of the W1 paper were examined to understand how well the isolating layers succeeded as a barrier, preventing transfer of volatile elements from the core to the archival object. Preliminary results indicate at these aging conditions, heavy duty aluminum foil was the best isolating layer.