Archaeological Adhesives

Abstract

An adhesive is any substance that bonds different materials together. This broad definition includes materials used in everything from hafted stone tools to monumental architecture. In addition, the combination of bonding, plasticity, and insolubility meant that some adhesives were exploited for waterproofing and sealing of materials, as self-adhering inlays and putties, and as paints, varnishes, and inks. Adhesives have a history of at least 200,000 years. Throughout (pre)history and around the world, people used materials, including bitumen/asphalt, carbohydrate polymers such as starches and gums, natural rubbers, mortars, proteins (from casein, soy, blood, and animal connective tissue), insect and plant resins, and tars made from various barks and woods. Adhesives thus are very diverse and have widely varying properties: they can be tacky, pliable, elastic, brittle, water-resistant, fluid, viscous, clear, dark, and much more. They are a plastic avant la lettre. These properties can and were tweaked by mixing ingredients or by further processing. In the study of archaeological adhesives, their characterization is essential and this is best done with chemical and spectroscopic methods. When larger coherent samples as opposed to single finds are analyzed, adhesive studies can provide data on past technologies, socioeconomic organizations, and environments and raw material availability. Through sourcing and mapping of ingredients and adhesive end products, travel and transfer of materials and knowledge can be illuminated. Additionally, experimental reproductions provide data on technological aspects that otherwise are lost in the archaeological record. An archaeology of adhesives can reveal the transport networks, subsistence, mobility strategies, division of labor, and technological know-how that held societies together.

Working Ethically with Ancient DNA from Composites in the United States

“…Small amounts of birch pitch can be common at European archaeological sites (Jensen et al 2019;Kashuba et al 2019;Mazza et al 2006;Ottoni et al 2021;Rageot et al 2021;Sykes 2015). Although birch pitch is not found in North American archaeological sites, other plant pitches, adhesives, and gums are found that could contain similar materials and genetic traces as birch pitch (Fox et al 1995;Langejans et al 2022). Pitches can be found with tooth and tool marks and, in some cases, fingerprints (Aveling and Heron 1999;Kashuba et al 2019;Sykes 2015).…”

Material and Sensory Experiences of Mesolithic Resinous Substances

“…We further define ‘resin’ as a viscous hydrophobic exudate, primarily composed of terpenes and collected directly from a tree or plant without the need for initial thermal processing, although this does not preclude secondary processing (Modugno et al 2006; Pollard & Heron 2015). Pitch and tar are sometimes used interchangeably, with ‘pitch’ often used to describe the solid/semi-solid portion of resins and tars, but confusingly sometimes used to refer to the tapped resin from certain trees (Langejans et al 2022), which is why it occurs frequently within archaeological and ethnographic texts. To avoid confusion, other than the appearance of ‘pitch’ within our ethnographic data tables, which respects the original published wording, we will avoid using this term.…”