Investigation the effect of Thiophanate-methyl on the ageing of Gall ink of the historical papers

The conservation and preservation of historical paper as cultural and historical heritage against harmful factors such as microorganisms is important. It was shown that the thiophanate methyl antifungal in 200 PPM concentration could inhibit destructive effect of several fungi on paper without negative effects. However, it is necessary to complete the studies by investigation the effect of thiophanate methyl on other materials used in historical paper, including inks.In this research, the effect of thiophanate methyl on gall ink as the most widely used ink in historical paper was studied.For this purpose, after the ink preparation and placing it on the paper surface, the samples were immersed in a solution containing thiophanate methyl, and the effect of accelerated aging on gall ink and treated gall ink were investigated by determination of pH, color, and tensile strength of paper as well as by FTIR-ATR spectroscopy and SEM microscopy. The pH results showed that the gall ink is highly acidic, which causes the acid hydrolysis reaction lowering the paper strength. Moreover, thiophanate methyl in concentration of 200 ppm brightens the color of the gall ink. Due to the adverse effect of paper immersion on paper strength, the treatment should be conducted by spray method. Overall, although thiophanate methyl could protect the historical papers against fungus, but it showed various adverse effects on the gall ink that should be considered.