5 CONCLUSIONS

Chitosan is of interest for the field of conservation, probably not only for paper but also for other materials such as skin, leather, parchments, wood, textiles, and photographs. Some investigations have been done with wood and textiles (Sadov and Markova 1954; Furukawa and Yamamoto 1990; Kumagai et al. 1990; Lee et al. 1993).

Chitosan products protect paper from deterioration more than cellulose ethers do. The probable mechanism is a mechanical barrier that could impede penetration of hyphae. At the same time, a real inhibition of the growth of fungi can occur, but the degree of protection depends greatly on the kind of fungi attacking. It is important to evaluate chitosan's toxicity to specific strains of fungi so the protection mechanism of chitosan on paper can be clarified.

The zero-span tensile strength test is a sensible means to grade the deterioration of paper, as much as it is a good parameter to test the effectiveness of the antifungal treatment afterward. Sterilization before inoculation of the paper with fungi was necessary to avoid contamination and for specific evaluation of each strain.

The prospect of employing products of chitosan in considering the techniques of document conservation will be interesting, since they simultaneously protect against attacks by micro-organisms and reinforce the paper's physical strength.

Obviously we do not yet have a perfect antimold consolidant for paper, but our results show that we are closer to finding one, because chitosan can be modified and can produce many different derivatives to improve its properties for specific applications.

We hope this work will spark interest in the possibilities of using chitosan for the conservation of artwork and historical objects.