Fungi and bacteria are important causes of damage to historical textiles. Many methods are used to resist innate damage in historical textiles. The study aim was to use an innovative method that loaded a mahogany plant extract onto natural chitosan and gelatin nanocomposite polymers to prepare chitosan / mahogany plant extract composite and gelatin mahogany plant extract nanocomposite and evaluate their potential for protecting historical textiles from biological damage. The fungi and bacteria found on historical textile samples were identified by biochemical methods. We performed an antifungal activity assessment of the mahogany-natural chitosan and mahogany-gelatin polymers to study the effect of these materials on the mechanical, chemical, and optical properties of dyed linen textiles. New linen fabrics dyed with madder, turmeric, and pomegranate were mordanted with alum, copper, and iron mordants. These materials were applied to dyed linen fabrics, and then the treated linen was artificially aged. The mechanical, chemical, and optical characteristics of the dyed linen fabric were examined by scanning electron microscopy, Fourier-transform infrared spectroscopy, CIELab, the tensile strength and elongation test, and the air permeability test. Mahogany - chitosan was more effective than mahogany - gelatin as an antifungal and antibacterial treatment of dyed linen and caused fewer changes in the mechanical, chemical, and optical characteristics. The mahogany - chitosan composite is recommended for preservation of historical linen textiles.
