ANTIFUNGAL PROTECTION AND SIZING OF PAPER WITH CHITOSAN SALTS AND CELLULOSE ETHERS. PART 1, PHYSICAL EFFECTS
MARIA DEL PILAR PONCE-JIMÉNEZ, FERNANDO A. LÓPEZ-DELLAMARY TORAL, & EZEQUIEL DELGADO FORNUÉ
The purpose of this project was to evaluate chitosan as a possible alternative in the consolidation of paper. In the second part of this report, we will analyze chitosan's antifungal properties (Ponce-Jiménez et al. 2002). Based on the results obtained, we found that the 2% solutions of chitosan were more fluid and better able to impregnate paper than 2% cellulose ethers, penetrating quickly through the fibrous net. All coatings caused a lowering of brightness in paper, a result that is more evident in chitosan coatings. Conservators should use a cleaner and more transparent chitosan to achieve the best results. No degradation of zero-span tensile strength occurs as a consequence of the application of any of the polymers tested.
Cellulose ethers “relax” paper and decrease the cohesion of its fiber network. On the other hand, chitosan reinforces the wet and dry strength immediately, providing an advantage for conservators when handling moist paper.
No tests have been done using original documents because the long-term effects of chitosan on the paper and its effects on inks and pigments have not been investigated. It appears reasonable to use chitosan products as consolidants since they reinforce the resistance properties of paper (folding endurance and zero-span tensile strength). Using a high-quality, bleached-grade chitosan as a sizing agent is essential for achieving the minimum diminution of the optical properties of the paper. The chitosan should be applied after a thorough dry cleaning of the document surface. Also, a procedure either to neutralize the acidity or to use a neutral derivative of chitosan should be used. More research is needed, as this article represents only a first step in investigating the potential use of chitosan in the conservation field.
The prospect of employing chitosan compounds as a technique of document conservation is interesting because they can be used as sizing or consolidant agents. If chitosan and its derivatives become available with a high enough purity and neutral pH, the conservator is guaranteed greater success.
We wish to thank the following institutions and people for their support and for making this work possible: Karl Augustin Grellman Institute of Wood, Cellulose, and Paper, University of Guadalajara, Guadalajara, Jalisco: José Turrado Saucedo, chemical engineer and head of the technology laboratory; José de Jesús Rivera Prado, chemical engineer, the bleaching laboratory; Salvador Pérez Ramos, chemical engineer, the physical-mechanical tests laboratory; Francisco Velázquez Cervantes, chemical pharmacology biologist, and Leticia Maya of the chemistry laboratory; Professor Bruno Becerra Aguilar of the technology area; Luz Elena Arce Castillo, chemical engineer, the library and publications area. University Center of Biological and Agronomical Sciences. Professor Rosa María Domínguez Arias of the University of Guadalajara. Mexican Institute of Social Security Clinic 46 in Guadalajara: Maria Luisa Preciado Quiroz and María de Jesús Najar. Mercedes Gómez Urquiza, director of the Manuel del Castillo Negrete National School of Conservation, Restoration and Museology. Luis Daniel Mario Goeritz Rodriguez, engineer and director of the National Institute of Anthropology and History Veracruz Center. We also thank Daniel McGonagle for assistance in translating part of the text.