1 INTRODUCTION

THE EVALUATION of scientific results and recommendations in conservation literature is greatly aided by a good understanding of the rationale behind the selection of test materials and methods. Unfortunately, space rarely permits the authors to explain fully such important issues as how the chemistry of the system under study has influenced their approach to the selection of analytical methods; the extent to which these experimental procedures can be expected to yield the desired information; and how closely the scientific model approximates the “real life” situations that the conservator meets in his or her laboratory.

The thought processes used in setting up a major project depend upon the particular preservation issues being investigated as well as the materials under study. If the issues are explored in depth and the data are interpreted with insight, it is often possible to gain information about the materials that were not part of the original intent of the project. It is also possible that the problems addressed in the project may be relevant to other related materials. For example, cellulose is one of the main components of both paper and basketry; a chemically based study of one of these materials could be useful in predicting the chemical behavior of the other. Therefore, any detailed explanation of the rationale behind a project will be useful in understanding and evaluating the results of many other scientific studies.

It was with these ideas in mind that we decided to write a detailed account of the planning of a scientific project currently under way in the Conservation Processes Research Division of the Canadian Conservation Institute (CCI). This project is a collaborative research effort with the Getty Conservation Institute (GCI) and the Smithsonian's Conservation Analytical Laboratory (CAL); its aim is to investigate the effect of sulphuryl fluoride (Vikane) on materials commonly found in museum collections.

This article presents a detailed explanation of the planning of CCI's portion of this project, together with the pertinent information used in making important decisions. The numerical results of the project, along with interpretations and recommendations for the conservator, will be presented in subsequent papers. A literature review of the properties of Vikane as a chemical fumigant may be found in an article published by the three collaborating institutions (Derrick et al. 1990).

The specific role of CCI in the Vikane project is to examine cellulosic and ligneous fibers; GCI is responsible for studying pigments/stones, metals, resins, and oils/waxes; and CAL is investigating proteins and dyes. With all these materials, a project of this type could potentially have applications for paper, textiles, wood, paintings on canvas, and a very wide range of composite ethnographic and archeological artifacts. Yet encompassing so many areas is clearly not possible given a reasonable amount of time and resources. Therefore, the first important decision that needed to be made was how to limit the area of investigation. After discussions with conservators and scientists in CCI, we decided to limit our investigation to paper and textile materials. The cellulose and lignin in these particular fibers are present in a relatively pure form. This focus has the advantage of allowing for a straightforward analysis and interpretation of data. It is expected that information relating to the effects of Vikane on cellulosic and ligneous paper and textiles will have considerable application to other materials that also contain significant amounts of these fibers.

A very brief summary of the chemistry of Vikane as it relates to the study of cellulose and lignin is given in section 2. Understanding the chemistry of sulphuryl fluoride is necessary to decide what analytical procedures will be used to monitor the changes (if any) introduced by fumigation of the fibers by sulphuryl fluoride. This knowledge, coupled with information about the reactivity of the various components found in paper and textiles, permits production of some likely reactions between the sample material and the fumigant. Other considerations arise from possible impurities in the commercial product and/or special conditions imposed by the method of fumigation (concentration, temperature, RH, etc.). The conclusions reached after consideration of the pertinent literature were that degradation of the fibers by Vikane is most likely to proceed by acid hydrolysis.

Section 3 describes the materials selected for the project and discusses the criteria used, considers the important variabilities among the samples and their influence on sample selection, and presents an initial characterization of the samples. The analytical data for this initial characterization are given. For the results of this project to be of practical value to the conservation field, the samples selected have to bear some similarities to the type of artifacts found in museum collections. Therefore, considerable time and effort went into obtaining a wide variety of potential sample material.

The analytical techniques chosen for this study are outlined in section 4. A summary of the procedure is given as well as any pertinent chemical reactions. The benefits and disadvantages of the individual methods are discussed. As this project is the largest, in terms of the variety of paper and textile materials studied and the number of analytical techniques used, carried out by the Conservation Processes Research Division of CCI, it provides an unusually broad view of the materials and analytical methods that can be used in scientific investigations of its type. Although care is taken to comment on any special circumstances that relate specifically to the Vikane project, the vast majority of the information in the analytical techniques section will be of general use to readers who wish to know more about the procedures used by cellulose and lignin chemists. The information should also help those not familiar with the field to evaluate and understand many of the investigations in the technical literature.

The method of sample preparation will be outlined in future articles along with the analytical data arising from the experiments. The paper and textile materials samples were fumigated at the same time, according to the published experimental protocol (Derrick et al. 1990).