LAUSR

Abstract Improper storage conditions may cause fungal contamination of old paintings. In this regard, gamma radiation which is an effective method for fungal decontamination of objects can be applied. However, the side effect of this method, the change of colors due to gamma radiation, should be investigated. In this study, to define the dose of decontamination, painted canvases with mixtures of two mineral pigments and binder were prepared and used as model samples. These model samples were aged and then inoculated with spores of two common types of fungal strains, Penicillium chrysogenum, and Aspergillus niger. The fungal radiation sensitivity (D10 value) on the samples was determined. The minimum sterilization dose of gamma-ray (Dm) for decontamination was calculated according to the D10 values, and 3 logarithmic cycles reduction of initial contamination. Results showed that D10 values of Penicillium chrysogenum ATCC 12690 and Aspergillus niger CBS 104.57 spores on model samples were 1.47 ± 0.3 and 0.702 ± 0.13 kGy respectively. Sterility test presented Dm of 5 kGy as sufficient dose to achieve 3 logarithmic cycles reduction of initial contamination. Also, in this study, the changes of the model colors due to the irradiation process were evaluated by using the colorimetric method. For this purpose, after the aging of model colors, the aged samples were irradiated at a dose of 5 kGy (Dm). Colorimetric results for fresh, aged, aged & irradiated model colors were obtained and revealed that the irradiation process with a dose of 5 kGy did not induce any significant color alterations.