SUGAR REFLOTATION - AN ALTERNATIVE METHOD FOR SORTING FLOTATION-DERIVED HEAVY FRACTION SAMPLES

Flotation systems cannot always achieve 100% separation of carbonized plant remains from archaeological samples. When soils are especially c lay-rich or moist, the effectiveness of flotation decreases. As a resu lt, paleoethnobotanical specimens are frequently mixed with heavy frac tion remains and require a second stage of processing to isolate them from other artifacts. Although chemical flotation techniques provide o ne means of separating carbonized plant remains from heavy fractions, these methods can be expensive and frequently require the use of hazar dous or toxic chemicals. This paper describes an alternative method of processing heavy fractions using sugar to increase the specific gravi ty of solution. We use one gallon of tap water mixed with 2.5 lb of su gar to form a solution with an approximate specific gravity of 1.11 g/ ml. This solution is capable of floating charcoal and seeds, but is no t dense enough to float bone, lithics, or fired clay. Using this techn ique, recovery rates between 96-100% were obtained from samples excava ted in the Mississippi Valley of NE Louisiana. Modern plant remains we re carbonized and subjected to the sugar reflotation procedure. Result s of these experiments indicate that this method does not lend to exce ssive breakage or damage. The sugar flotation method is inexpensive, e asy to use, does not unnecessarily harm the carbonized plant materials , and achieves consistently high rates of recovery.