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Bathtub Research Project



Residue Analysis

Residue Analysis

For this project, we sampled a number of ancient 'bathtubs' from a variety of archaeological contexts for traces of organic residues that might provide insight into the function of these tubs in antiquity. Our hypothesis that these tubs were used for wool processing suggested that the primary residue we would find would be lanolin but, in this preliminary investigation, we did not rule out the possibility of other trace residues.The process of establishing a sampling procedure included the following goals:

  • Perform non-destructive sampling when possible
  • Utilize isolated sampling areas that would not contaminate future studies
  • Establish future sampling techniques that archaeologists can employ when tubs are found
  • Determine which solvent was most effective at extracting organic lanolin residues
    Retain overall aesthetic impression of the tub 

The goal of utilizing a non-destructive technique was accomplished by obtaining samples through the process of swabbing the area of interest. The analysis of the powdered samples and surface collections with the swabs would consist of:

  • Fourier Transform Infrared (FT-IR): identify traces of organic residues in the ceramic and limestone matrices of the tubs.
  • Light and Electron Microscopy: characterize the type of clay and physical surface features
  • Energy Dispersive X-Ray (EDX) Spectroscopy: identify and quantify the inorganic components of
    the samples collected
  • Gas Chromatography (GC/MS): identify specific volatile organic compounds

Several researchers have assisted us in the process of analysis. Dr. Anthony Kennedy specializes in the use of FT-IR to examine organic compounds. Dr. Noreen Reber operates a pottery organic residue analysis laboratory at UNC-W and performed preliminary analysis using GC/MS. In addition to colleagues in the US, Dr. Dvora Namdar and Dr. Steve Weiner have also provided useful suggestions from the Kimmel Center for Archaeology at the Weizmann Institute for Science in Israel.