Removing lichen from lithic artifacts

In response to C. Jackson and M. Smith:

We deal with lithic artifacts on a daily basis here, being an
archaeology department, though we have never had to remove lichen.
While the methods recommended by Smith should remove the lichen
while preserving traces of use-wear, it will destroy any organic
residues.  Research over the past decade and a half has shown that
many artifacts, especially lithics, retain residues, most often
blood, from whatever they were used on.  Often, these residues can
not be seen.  Washing, especially with alcohol, will destroy these
completely.

I asked D. C. Hyland, one of our faculty members, who helped to
develop one of the methods for recovering blood from artifacts for
suggestions for how to remove lichen without destroying the
residues.  He could think of no way to do this, however, he thinks
that residues could be recovered while the lichen is still attached,
and then the artifacts could be cleaned.  If you have not yet
cleaned the artifacts, you may want to consider this. Also, if you
have cleaned them, they should be tested anyway to see if any
residues remain (perhaps you've accidentally discovered a way to clean
lichen from lithics without destroying residues).  See:

    Hyland, D.C., J.M. Tersak, J.M. Adovasio, and M.I. Siegel
    Identification of the Species of Origin of Residual Blood on
    Lithic Material. American Antiquity 55(1):104-111. 1990

    As an aside, there has been some experimentation with the use of
    Calgon for artifact cleaning in the archaeological community.  I
    have no idea of its usefulness on lichen, but it works well on
    regular dirt with a minimum of labor.  See:

        Neumann, T.W., and R.M. Sanford
        Cleaning Artifacts with Calgon. American Antiquity
        63(1):157-160. 1998

If you have any other questions on this, or need more data on these
two techniques, feel free to contact me.  We have a huge archive on
a lot of this stuff.

J. S. Illingworth
Analyst and Conservator
Mercyhurst Archaeological Institute
Erie, PA  16546
814-824-2581
Fax: 814-824-2594

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                  Conservation DistList Instance 13:31
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