The efficiency of clove (Eugenia caryophyllata) essential oil (C-EO) for the curative antifungal treatment of historic wood was investigated in comparison with two classical biocide products: a boron-based preservative (Diffusit S) and a formulation containing quaternary ammonium salts and isothiazole (Biotin T). A combined approach was adopted that consisted of implementation of C-EO in a practical case study on a degraded beech (Fagus sylvatica) wood artifact and evaluation of the treatment efficacy via an original laboratory mycological test. Small samples, extracted from the degraded wood material before and after curative treatments, were placed as inoculum on sterile culture medium and incubated for periodic monitoring of the emerging fungal growth for 140 d. Direct observation was supplemented with digital quantification of the fungal coverage area via ImageJ software and calculation of the absolute and relative indices of fungal development reduction. The results indicated that the C-EO solutions at both tested concentrations (10%, 5%) were more efficient than the considered reference products at similar concentrations (Diffusit S (10%) and Biotin T (5%)) for curative antifungal treatment. However, none of the treatments applied entirely prevented reactivation of the severe and complex fungal attack, which was highlighted by the mycological tests conducted on the control samples.
This paper investigates the potential of clove (Eugenia caryophyllata) essential oil (C-EO) as a wood protection system for use in cultural heritage conservation. The preventive and curative antifungal efficacy of C-EO was compared to a boron containing wood preservative (Diffusit S) in two laboratory tests on European beech (Fagus sylvatica) and Scots pine sapwood (Pinus sylvestris) mini-blocks. Non-sterile, air-infected wood samples were employed in the first test, while wood samples with active attack, as result of inoculation with three fungal strains isolated from cultural heritage sites, in the second test. Untreated controls and C-EO-treated wood blocks were incubated up to 150 days to monitor and quantify fungal growth. The experimental results showed antifungal efficacy of C-EO to be higher than that of the boron wood preservative at the concentrations used. Concentrations of C-EO 5 % -10 % in ethyl alcohol prevented mould growth for at least 150 days, while a concentration of 10 % delayed or suppressed active attack by decay fungi. This effect, determined up to 90 days of incubation, was dependant on the type of fungus.
Essential oils can be used as wood preservatives with antifungal properties. These kinds of products can be considered potential ecological wood preservatives for special applications, such as furniture conservation. The present paper refers to a laboratory screening test designed to allow a quick and reliable evaluation of the potential biotical effect of 3 types of essential oils. The tested products were: basil (Ocimum Basilicum), thyme (Thymus vulgaris), and oregano (Origanum vulgare) essential oils at 4 different concentrations. Two types of fungi were employed as biological material: a white rot (Trametes versicolor) and a brown rot (Postia placenta). Oregano and thyme essential oils demonstrated biocidal effect against both tested fungi, being more active against brown rot than white rot. This effect depends on the concentration of the essential oils. The biocidal potential of basil essential oil is very low.
The present research investigates the antifungal efficiency of clove (Eugenia caryophyllata) essential oil (C-EO) combined with linseed oil (LO) at different concentrations (1%, 5%, 10%) using two types of mycological tests: a qualitative screening test by agar diffusion method and a quantitative mini-block test on treated beech (Fagus sylvatica) wood.The agar diffusion test indicated improved protection of wood should be possible with a mixture of C-EO and LO from a concentration of 5%. In contrast, the mini-block test indicated that wood is partially protect by LO alone and that adding increasing quantities of C-EO gradually reduces this protection.One possible explanation of this unexpected result could be the antioxidant effect of C-EO which could negatively interfere in the oxidative curing process of LO. ESEM investigation revealed the penetration of LO and C-EO/LO mixtures into the wood structure and non-uniform fungal colonization of all the samples exposed to Postia placenta, as well as some characteristic features of consequent wood structure degradation, which was found more advanced for the untreated beech wood samples.
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