Applying the Techniques on Materials I

Microbial biofilms have developed on the surfaces and within the painted and gilded layers of mummy cartonnage at the Saqqara museum storeroom in Giza, Egypt. SEM–EDX, XRD and FT–IR–ATR techniques were applied to analyse the coloured and gilded materials, ground layer, textile support and binder used for the cartonnage. Aspergillus niger (24.8%), Penicillium chrysogenum (21.5%) and a novel cartonnage‐biodegrading bacterium, Bacillus sonorensis (23.7%), were the most abundant microbes growing over the cartonnage surface. In addition, Aspergillus tamari (15.4%), A. fumigates (8.1%) and Fusarium solani (6.5%) were identified. The pigments comprised Egyptian blue (cuprorivaite), cinnabar (red), orpiment (yellow) and green pigment made from a mixture of cuprorivaite and orpiment. Gold leaf was used for the gilded layer, calcium carbonate and gypsum comprised the ground layer, gum arabic was the binding medium and the fibre base was a fine linen textile. Microbial colonization tests were performed on aged cartonnage replica samples made from linen and pigments of similar composition to ancient pigments found in the cartonnage. Each sample was inoculated separately with A. niger, P. chrysogenum and B. sonorensis. Yellow orpiment samples were the exception, as no colour change was detected after colonization by the examined micro‐organisms.

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“…Changes in the colour values greater than 5 indicate an extreme colour difference (del Hoyo‐Meléndez and Mecklenburg ; Yurdun et al . ).…”

Section: Methodsmentioning

confidence: 97%

“…In the present study, a ΔE* value of 5 was used as an initial threshold value, and was considered large enough to be detected by most observers. Changes in the colour values greater than 5 indicate an extreme colour difference (del Hoyo-Meléndez and Mecklenburg 2011; Yurdun et al 2013).…”

Section: Colorimetric Measurementsmentioning

confidence: 99%