1 INTRODUCTION

THE CHARACTERISTIC EFFECTS of water on such properties as strength, rigidity, elasticity, and flexibility of papers and paper-based products have long been recognized in industry as dependent on constituent fibers, fillers, and sizing.1 Only relatively recently, however, has the effect on paper of water as a chemical reagent come under the scrutiny of conservators.

In a recent publication, Tang and Jones report results of a study aimed at establishing guidelines for acceptable water quality for paper conservation treatments.2 To document the effects of water washing on paper properties, they treated two types of paper with five types of water, varying both water purity and temperature. There was a correlation between water purity and pH, i.e., the extra pure waters were acidic, while the less pure waters were alkaline. The paper samples were relatively new newsprint and Foldur Kraft papers, both acid papers considered to have little permanence.

Tang and Jones found that highly purified water such as distilled or deionized water seemed to strip paper of beneficial constituents such as calcium, and they suggest that this might be why these samples showed a decrease in physical strength after artificial aging. Of great interest was the finding that the Washington DC tap water seemed to have a beneficial effect on the tested papers. In addition to calcium, this water was reported to contain significant amounts of the destructive agents chlorine, copper, and iron.

The present study had two objectives: first, to try to reproduce the observations of Tang and Jones, that different qualities of water have different effects on the strength of papers washed in them; second, to see if the effects observed on relatively impermanent papers would be apparent on more permanent papers as well.