Conservation treatments in the field: Sharing perspectives and experience

Jessica H. Johnson

Abstract

There have always been informal contacts between anthropological archaeology and professional conservation in the New World. Often contacts were developed when questions about field preservation developed and conservators offered suggestions for materials and techniques. Examining the history of specific field techniques, such as bone preservation, shows that many preservation techniques and materials used by archaeologists were originally suggested by conservators (Johnson in press). Over time the origin of the techniques has been lost, and the information and techniques are distorted in use, sometimes to the detriment of the preservation of artifacts. For example, names of materials are often shorted (Acrysol WS-24 to Acrysol; Acryloid B-72 to B-72) so that subsequent users of the material are not informed about the exact product that may have undergone some testing for use. Oral transmission of information between conservation and archaeology, without written recommendations or published reporting is not an effective or responsible way to support preservation of archaeological material.

Evaluating the origin and use of techniques shows that archaeologists and conservators each choose treatments based on different requirements. Generally, archaeologists have focused on the availability and working properties of materials so that material can be recovered more easily and analyzed quickly (how easy is it to apply?, does it work in the field?), while conservators generally are concerned with more long-term preservation (will the material deteriorate quickly, what chemical reactions occur that may cause later damage?). However, in both conservation and archaeology the effectiveness of many preservation techniques and materials used in conservation of archaeological material has not been critically evaluated, beyond simple visual examination and trial-and-error. For example, both conservators and archaeologists use acid to remove insoluble deposits from the surface of ceramics (Joukowsky 1980, Sease 1992). Little evaluation has been done to identify physical damage that may occur, such as destruction of temper or paste, or chemical changes such as oxidation of minerals that may occur. Controlled experimental studies on the effects and effectiveness of treatments must be done as part of multidisciplinary projects in the field and laboratory to develop techniques that preserve many kinds of data for many types of researchers.