| Egyptian Journal of Archeological and Restoration Studies

Authors:
Bakr, A. ¹ ; Abd El Hafez, M. <sup>2

1</sup> Asses. Prof. Conservation dept., Faculty of Archaeology, Cairo Univ., Giza, Egypt
² Asses. Lecture Conservation dept., Faculty of Archaeology, Cairo Univ., Giza, Egypt

Abstract:
This study discusses the assessment of the role of bats excretions (guano, blood and urine) in physiochemical degradation of historical stone surfaces for conservation purposes. The study was applied on the wall painting from Mohamed Ali palace (1812) located in Suez, Egypt. Certain parts of the inside walls of the palace suffer from the accumulation of bats excretions that lead to deformation, exfoliation and detachment of a large area of the paintings. The assessment was performed through characterization of the degradation products and the microbial activities. The study was carried out using various analytical methods such as optical microscope, scanning electron microscopy equipped with the energy dispersive X-ray (SEMEDX) system and X-ray diffraction (XRD). These complementary analytical techniques allowed the identification of the wall painting components and the degradation products accumulated on the wall painting surface. The data showed the presence of phosphates minerals: Brushite (CaHPO4.2H2O), Whitlockite (Ca,(Mg, Fe)[PO3OH/(PO4)6]) and Newberyite MgHPO4·3H2O). These minerals are most probably derived from bat guano (excrements).The microbiological study of accumulation excretions allowed the identification of some fungi such as: Aspergillus niger, Aspergillus flavus, Acremonium cerealis, Morterilla subtilssina and one kind of Gram+ve bacillus sp. (mono-dibble-strepto bacillus). Their metabolic activities play an important role in the physiochemical disruption of paint layers.

Keywords:
Bat excretions; Physiochemical degradation; fungi; Bacteria; SEM-EDX; XRD

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