Mural

I have a problem with a mural decoration from Safavid period (400
years old).  It is a painting on plaster with water soluble medium.
About 200 years after creating these decorations, they covered them
with a layer of gypsum plaster. How can i remove this plaster? With
mechanical method all the pigments will be removed. do you have any
idea about this?


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                  Conservation DistList Instance 17:7
                   Distributed: Friday, June 27, 2003
                        Message Id: cdl-17-7-009
                                  ***