River algae

Preparing an exhibition "Life in the Middle Ages", I have received a
quite large number of ceramic, glass and horn objects dating from
prehistory to recent times. They all have been found in the river
Ljubljanica flowing through Ljubljana (capital of Republic
Slovenija). All objects are covered with green and red algae.

Green algae are a few millimetres long and are deeply grown into the
pore of the object body. I try to remove them by soaking objects in
tap water and cleaning the surface by scalpel. The removal is very
time consuming and not complete or satisfactory. The horn object
could not be soaked so the results are even worse.

The red algae are in form of  stains. They are removable only from
the glass surfaces. Both types of algae are not removable with
peroxide or Biox conservation liquid (sold by Conservation
Resources).

    1.  Can somebody advice me some more efficient procedure for
        removing river algae?

    2.  Is anywhere any literature concerning this problem?

Zoran Milic
National museum of Slovenia
Presernova 20
Slo-1000 Ljubljana
+386 61 218 886
Fax: 386 61 221 882

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                  Conservation DistList Instance 10:62
                 Distributed: Friday, January 10, 1997
                       Message Id: cdl-10-62-014
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