Alkaline Earth Hydroxide Nanoparticles for the Inhibition of Metal Gall Ink Corrosion

This contribution reports about the application of alkaline earth hydroxide nanoparticles dispersed in alcohols to inhibit ink-induced degradation of paper objects. A single-step deacidification is shown to be effective in the protection of paper from acid hydrolysis and concomitant metal-catalyzed oxidation of cellulose if the final pH is stabilized around neutrality (pH 6-7). Nanosized particles of magnesium-and calcium hydroxide have been tested on model paper with different inks brushed on. Inks are prepared according to a 17(th)-century recipe. The efficacy of a nanoparticles pH-controlled deacidification was evaluated by determining the viscometric degree of polymerization of cellulose to gain information about the state of preservation of the paper. The applied deacidification methodologies provided an efficient neutralization, resulting in the inhibition of paper corrosion due to gall inks.