Mastic, one of the best natural varnishes, is frequently used as
protective and finishing layer or as component of oleo-resinous media
in paintings, both in the past and currently. However, this resin is
affected by complex deterioration processes which can change its
characteristics and thus the visual aspect of works of art. The
alteration processes caused by radiation have been widely studied, but
there is a lack of information on the biodeterioration of this natural
product. In this paper, fungi from collections as well as from oil
paintings of the Fine Arts Museum of Granada (Spain) were inoculated
onto slides covered with mastic. The samples, after an incubation
period of 15 days, were analysed by gas chromatography-mass
spectrometry (GC-MS) to identify the chemical changes undergone, and a
visual monitoring of the samples was performed to determine the
formation of mycelia onto solidified resins. Major changes were
detected in Chrysonilia sitophila, Phoma herbarum, and P. chrysogenum,
showing evidence of alteration processes caused or favoured by these
microorgamisms