, vol. 7, issue 4, 2016.
The main goal of this work was to investigate the biological fungicidal activity of some
commercial essential oils of tea tree, lavender and thyme, which were to be applied as
alternative preservatives for ancient manuscripts. To achieve our goal, model samples of
cellulosic paper were made to mimic the original manuscript, which was a Coptic manuscript
known as Pascha (the sacred week), dated 1812. Twenty-three microorganism strains were
isolated representing twelve fungal taxa and one bacterial taxa which were identified in all
collected and analyzed in samples, which included Trichoderma viride, Penicillium roqueforti,
Eurotium chevalieri, Aspergillus flavus and Bacillus subtilis. A scanning electron microscope
(SEM) was used to investigate the growth of the associated microorganisms and their effect on
the sample paper structure. Different concentrations of the aforementioned essential oils were
applied on the mimic samples, which were then subjected to accelerated ageing corresponding
to 25 or 50 years of a natural one. To characterize the applied oils on the samples, we made
records by using FTIR-ATR, color measurements according to CIELAB system, and analyzed
the mechanical properties of the tested samples. The results revealed that the samples treated
with either tea tree oil or lavender oil, had ΔE values that decreased as the oil concentration
increased. However, when samples were treated with thyme oil the reverse was obtained. For
the treated samples exposed to 25 years of light ageing, we noticed that the higher obtained
tensile strength and % elongation of treated samples followed the ranking order: thyme >
lavender > tea tree oils. For the treated samples that were exposed to 50 years of natural light
ageing, we observed that almost all tensile strength and elongation values of the treated
samples were higher than that of the untreated ones. Moreover, we noticed that the inhibition
of growth of the microorganisms was obtained at a low concentration of tea tree oil (0.25%
v/v). This treatment was esthetically acceptable for archaeological objects, because it was
colorless, transparent and safe. Based on the results we obtained, the optimized essential oil,
which is the oil with an appropriate concentration, was selected to be added to the cellulosic
pulp used for the leaf casting. Moreover, the same optimized essential oil was applied on the
paper samples to be used as separators between the ancient manuscript pages. After
dismantling, cleaning, leaf casting and rebinding of the damaged parts, the manuscript is then
preserved.
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