1 INTRODUCTION

Although the process of deacidification and its beneficial effects in retarding the degradation of paper were extensively studied by Barrow3 and are in common use among conservators today, many details are left to the judgment of conservators. As a result, we have encountered three questions repeatedly. These are:

1. How long must a sheet be soaked in a deacidification bath for complete deacidification and maximum pickup of alkali as an alkaline reserve?
2. What causes the occasional formation of a gritty surface on deacidified sheets and how can this be avoided or corrected?
3. What is the cause of poor penetration or incomplete deacidification when deacidifying with magnesium methoxide or methyl-magnesium carbonate solutions?

Of course, none of these questions has a simple answer because of the number of variables involved. We therefore initiated a series of brief studies to clarify the problems involved in these questions and to illustrate the effect of some of the variables. The studies are by no means exhaustive, but the results should increase the understanding of the problems and offer guidance in overcoming them.

Since magnesium and calcium bicarbonate solutions are prepared from the corresponding carbonates by reaction with carbon dioxide in solution, and since these solutions redeposit the carbonate on drying, it is convenient to refer to the concentrations in terms of the carbonate rather than the bicarbonate. In this paper, all calcium or magnesium bicarbonate concentrations are given in terms of the equivalent carbonate concentration.