A polysaccharide extracted from sphagnum moss as antifungal agent in archaeological conservation

On the basis of the well-known preservative properties of Sphagnum moss, a potential opportunity to use moss polysaccharides (Sphagnan) in art conservation was tested. Polysaccharides were extracted from the moss (S. palustre spp.) in the amount of 4.1% of the Sphagnum plant dry weight. All lignocelluloses were removed from this extract as a result of the treatment of the moss cellulose with sodium chlorite. The extracted polysaccharide possessed a strong acidic reaction (pH 2.8) and was soluble in water and organic solvents. The extract was tested on laboratory bacterial cultures by the disk-diffusion method. The antibacterial effect was demonstrated for E. coli and P. aeruginosa (both gram-negative) while Staphylococcus aurelus (gram-positive) was shown to be insensitive to Sphagnum polysaccharides. The antifungal effect of Sphagnum extract was tested by the disk-diffusion method on the spores of seventeen fungal species. These fungi were isolated from ethnographic museum objects and from archaeological objects excavated in the Arctic. Twelve of these isolates appeared susceptible to the extract. The inhibiting effect of the extract was also tested by the modified broth-dilution method on the most typical isolate (Aspergillus spp.). In this experiment, in one ml of the nutritious broth, 40µl of 3% solution of polysaccharides in water killed 10,000 fungal spores in 6 hours. The inhibiting effect was not connected to the acidity or osmotic effect of Sphagnum polysaccharides. As an example of the application of Sphagnum polysaccharides in art conservation, they were added as preservative agents to conservation waxes. After three weeks of exposure of microcrystalline wax to test fungi (Aspergillus spp.), 44% of wax was consumed. When, however, ~ 0.1% (w/w) of Sphagnum extract was mixed with wax, the weight loss of wax was only 4% in the same time interval. On the basis of this study it was concluded that Sphagnum moss and Sphagnum products can be recommended for use in art conservation as antifungal agents.

The Effects of Several Paper Characteristics and Application Methods on the Sublimation Rate of Cyclododecane

Cyclododecane (CDD) is a waxy, solid cyclic hydrocarbon (C12H24) that sublimes at room temperature and possesses strong hydrophobicity. In paper conservation CDD is used principally as a temporary fixative of water-soluble media during aqueous treatments. Hydrophobicity, ease of reversibility, low toxicity, and absence of residues are reasons often cited for its use over alternative materials although the latter two claims continue to be debated in the literature. The sublimation rate has important implications for treatment planning as well as health and safety considerations given the dearth of reliable information on its toxicity and exposure limits. This study examined how the rate of sublimation is affected by fiber type, sizing, and surface finish as well as delivery in the molten phase and as a saturated solution in low boiling petroleum ether. The effect of warming the paper prior to application was also evaluated. Sublimation was monitored using gravimetric analysis after which samples were tested for residues with gas chromatography-flame ionization detection (GC-FID) to confirm complete sublimation. Water absorbency tests were conducted to determine whether this property is fully reestablished. Results suggested that the sublimation rate of CDD is affected minimally by all of the paper characteristics and application methods examined in this study. The main factors influencing the rate appear to be the thickness and mass of the CDD over a given surface area as well as temperature and ventilation. The GC-FID results showed that most of the CDD sublimed within several days of its disappearance from the paper surface regardless of the application method. Minimal changes occurred in the water absorbency of the samples following complete sublimation.