Archaeological wood properties

Rowell, R. M. and R. J. Barbour (eds.) (1990), Archaeological Woods Properties, Chemistry and Preservation, Advances in Chemistry Series, American Chemical Society, Washington, DC. 

Hafors B (1990) The role of the Vasa in the development of the polyethylene glycol preservation method. In Rowell RM and Barbour RJ (eds), Archaeological wood properties, chemistry and preservation. Advances in Chemistry Series 225. American Chemical Society, Washington DC, 195-216... 

Table I Archaeological Wood. Properties of Resins and Their Strengthening Capability ... 

Archaeological wood properties, chemistry, and preservation Roger M. Rowell, editor, R. James Barbour, editor, p. cm.—(Advances in chemistry series, ISSN 0065-2393 225)... 

RoweU, R.M., Barbour, R.J. (1990) Archaeological Wood Properties, Chemistry, and Preservation. Washington, DC American Chemical Society. 

He began by making species identifications of wood recovered from the Hoko River Site, which is located on the Olympic Peninsula in Washington. He soon realized that there was a need for further research into the properties of archaeological wood and how these properties influence the outcome of various conservation treatments. This was the topic of his master s thesis, which was written at the University of Washington in Seattle, Washington. 

We hope that this book will provide some understanding, from a scientific perspective, of archaeological wood, its properties, its chemistry, and its preservation. 

The density of archaeological wood will at best be equal to the values for recent wood at worst, it will approach zero as the wood nears total destruction. In general, density will be somewhere between these limits. The degree to which the density deviates from values of recent wood is a measure of the extent of deterioration. However, it is not unusual to find archaeological wood that has significantly lower strength properties than recent wood without showing any reduction in density 4, 5). 

A HE AVAILABILITY AND UNIQUE PHYSICAL PROPERTIES of WOod have made it the material of choice since antiquity for the fabrication of shelters, tools, transportation devices, and objects of art (1). Although wood is among the most resistant of all organic materials, its usual environmental fate is eventual decay. Wooden objects are preserved for long periods of time only under extremely cold, wet, dry, or anoxic conditions. Because wooden artifacts provide a rich and varied record of our early activities and technology, the characterization and preservation of archaeological wood is a subject of wide interest. 

The appearance and physical properties of fresh and archaeological woods depend in large part on the chemical composition of the material. In turn, the chemistry of wood is intimately related to its structure. Although all woods comprise primarily polysaccharides and lignins, the types and... 

Such clear-cut distinctions, however, are often difficult to make because the early histories of many samples are not well known. In addition, the literature on the chemical composition of dry archaeological wood is so sparse that comparisons to waterlogged counterparts are not very informative. Therefore these two wood types will be discussed together, but distinguished where possible. The focus of the following section will be on chemical properties that most older woods from natural environments hold in common and likely reasons for these characteristics. 

In this chapter, archaeological wood is defined as wood that, as a result of time, exposure, and possibly conservation-related treatments (e.g., consolidation or stabilization), may have gluing properties or limitations signif-... 

PEG-Treated Wood. Wood treated with PEG will also have modified gluing properties, although, if properly redried, not as much so as heavily consolidated wood. The use of PEG as a dimensional stabilization treatment was developed in the 1950s (20) and it has been used on a limited scale since then. The utility of PEG treatment for waterlogged archaeological wood is now widely recognized, and it is quite possible that some of the wood so treated has been or will need to be glued. 

Wood that has survived archaeological time and conditions will undoubtedly have gluing properties that are, in varying degrees, different from those of fresh unmodified wood. Bulk strength may have been reduced and fluid permeability and absorbency increased. Surfaces, in particular, may have strength and wettability that have been altered by aging. Treatment with consolidants and dimensional stabilizers may have been necessary, and this will often leave surface residues and reduce permeability and absorbency. 

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