Artifact Washes
Nicole M. Arendt
July 21, 2004.

There have been many studies that attempt to determine the function of artifacts. These involve studies of botanical remains associated with artifacts, including fibers, phytoliths, and pollen. An often used and potentially very important, although little written about, aspect of archaeological pollen analysis, is artifact washes. These involve the recovery and analysis of pollen directly from the surface of artifacts, such as complete ceramic containers and lithic artifacts, especially, grinding tools. These analyses can provide information both on the plants used at the site where the artifacts are found and on the uses of the artifacts themselves (Adams and Gasser 1980; Bohrer 1981; Bohrer and Adams 1977; Bryant and Holloway 1983; Pearsall 2000; Shafer 1979).

Pollen washes can be used on whole vessels or lithic artifacts. The artifact to be treated should be covered as soon as possible after being uncovered to protect it from contamination with modern pollen and as much matrix as possible left to protect the surface to be treated from the same (Adams and Gasser 1980; Bohrer and Adams 1977). The loose soil is removed, exposing the use surface, which is then washed with distilled water or dilute HCl (if calcium carbonate deposits are present) and the liquid is collected (Adams and Gasser 1980; Bohrer and Adams 1977; Pearsall 2000:281-282). While the acid could damage the artifact, the calcium carbonate deposits could interfere with the loosening of the pollen from the surface. Both of these factors must be considered before the treatment (Bohrer and Adams 1977). In some cases, the artifact is pre-washed (with distilled water) or pre-cleaned (by brushing) prior to sampling with acid to remove any background pollen (Kelso and Good 1995). This liquid is then processed for pollen extraction, which is then analyzed. A sample of the floor or surrounding matrix should also be collected and analyzed for comparison with the artifact wash (Adams and Gasser 1980; Bohrer 1981; Kelso and Good 1995). If the pollen found on the artifact differs from the that in the control, this could indicate that the pollen from the artifact could reliably indicate its function.

Several have suggested that only complete vessels from "undisputed archaeological contexts" be treated in this manner (Adams and Gasser 1980; Bohrer and Adams 1977:22). This probably ensures that the pollen recovered is most likely to have been from the use of the artifact, rather than from the pollen rain or other post-use processes. While at a small site, all such vessels can be treated, sampling is required for larger sites with an abundance of complete vessels, such as Salmon Ruin (Bohrer and Adams 1977).

Pollen from these artifacts can indicate what was contained in these vessels or ground on these tools. While these include cultigens, such as maize, they also often include wild plants, which may even have been encouraged (for example, see Bohrer 1982; Hevly 1981). While pollen was found in the organic residue adhering to flaked stone tools in one study, it is not discussed specifically (although this does indicate the potential for the use of pollen washes on these artifacts). This study, examining flake tools from an Archaic rock shelter in southwest Texas, found that other evidence, including fibers and phytoliths, indicate the use of many of these for slicing or scraping desert succulents (Shafer 1979). These studies demonstrate the ability of this technique to study the economic uses of both cultivated and non-cultivated plants.

While not exactly artifact washes, many studies also study the matrix found in or adhering to these artifacts (for examples see Bohrer 1968; Bohrer and Adams 1977; Hevly 1964). While this could provide similar data, , it should be used carefully and compared with a control sample from the surrounding matrix, as the fill can often be similar to or the same as the matrix surrounding it (Kelso and Good 1995). For this reason, this technique is not as reliable as artifact washes. Therefore, artifact washes are a very important means for understanding the economic uses of plants. These include the storage and processing of plants (including the function of storage and processing tools). However, these storage and processing artifacts recovered and treated might not have bee used with the full range of plants utilized, so this form of analysis must be combined with others to fully understand prehistoric subsistence.


Adams, K. R., and R. E. Gasser 1980.
Plant Microfossils from Archaeological Sites: Research Considerations, and Sampling Techniques and Approaches. Kiva 45(4):293-300.

Bohrer, V. L. 1968
Paleoecology of an archaeological site near Snowflake, Arizona. Ph.D. dissertation, University of Arizona.

__________ 1981
Methods of Recognizing Cultural Activity from Pollen in Archaeological Sites. Kiva 46(3):135-142.

__________ 1982
Plant Remains from Rooms at Grasshopper Pueblo. In Multidisciplinary Research at Grasshopper Pueblo, Arizona, edited by W. A. Longacre, S. J. Holbrook, and M. W. Graves, pp. 97-105. Anthropological Papers of the University of Arizona no. 40. University of Arizona Press, Tucson.

Bohrer, V. L., and K. R. Adams 1977
Ethnobotanical Techniques and Approaches at Salmon Ruin, New Mexico Contributions in Anthropology v. 8, no. 1. Eastern New Mexico University, Portales.

Bryant, V. M., Jr., and R. G. Holloway 1983
The Role of Palynology in Archaeology. In Advances in Archaeological Method and Theory, pp. 191-219. vol. 6, M. B. Schiffer, general editor. Academic Press, New York.

Hevly, R. H. 1964
Pollen Analysis of Quaternary Archaeological and Lacustrine Sediments from the Colorado Plateau. Ph.D. dissertation, University of Arizona.

__________ 1981
Pollen Production, Transport and Preservation: Potentials and Limitations in Archaeological Palynology. Journal of Ethnobiology 1(1):39-54.

Kelso, G. K., and I. L. Good 1995
Quseir Al-Qadim, Egypt, and the Potential of Archaeological Pollen Analysis in the Near East. Journal of Field Archaeology 22:191-202.

Pearsall, D. M. 2000
Paleoethnobotany: a Handbook of Procedures. 2nd ed. Academic Press, San Diego, California.

Shafer, H. J. 1979
Organic Residue Analysis in Determining Stone Tool Function. In Lithic Use-Wear Analysis, edited by B. Hayden, pp. 385-399. Academic Press, New York.