Removing lichen from lithic artifacts

Carrie F. Jackson <carjacks [at] prairie__nodak__edu> writes

>I am seeking information for our laboratory on the removal of lichen
>from lithic artifacts.  We have a number of artifacts that were
>surface collected from an archeological site in North Dakota in the
>summer of 1999.  They have been stored in paper field sacks since
>their collection.  We are looking for direction on how to safely
>remove the lichen from the artifacts, if possible.

I've asked my son, who is a Ph.D. candidate in archaeology and whose
specialty is lithic usewear analysis, what they do in cases of
lichen on lithic artifacts.  Here is his answer--he is not involved
in preservation as such, however he has much experience with these
type of objects.

    I would recommend soap and water and/or alcohol.  The main point
    is to avoid abrasion or scrubbing which would possibly effect the
    usewear traces on these tools (assuming they were used). Alcohol
    and soap and water cleaning have not been found to damage
    usewear traces, such as polishing.  Perhaps a good soaking will
    soften the lichen, which could then be removed with a soft
    brush, e.g. a toothbrush, or a cloth.  Just stay away from the
    edges of the artifact, as that is where the usewear will be
    (mostly) and it may be of use to later researchers.

Margit J. Smith, Asst. Prof.
Head of Technical Services
Copley Library
University of San Diego
5998 Alcala Park
San Diego CA 92110-2492
619-260-2365

                                  ***
                  Conservation DistList Instance 13:29
                 Distributed: Friday, November 12, 1999
                       Message Id: cdl-13-29-001
                                  ***