Calcium hydroxide nanoparticles in hydroalcoholic gelatin solutions (GeolNan) for the deacidification and strengthening of papers containing iron gall ink

A severe decay process, catalyzed by acidity and metal ions, affects cellulose in historical manuscriptsand books that contain iron gall inks. The inhibition of this process can be achieved by alkaline-earthnanoparticles dispersions in alcohols, which create a neutral environment in which both oxidation anddepolymerization of cellulose are hindered. As a result of the degradation process, paper in historicalmanuscripts and books is fragile and very difficult to handle. A reinforcement intervention with gelatinand Japanese tissue could be used for the strengthening of historical manuscripts, even if this methodcould not prevent paper degradation due to iron gall inks. Therefore, a new method, combining a deacidi-fication treatment based on calcium hydroxide nanoparticles and a reinforcement process using Japanesetissue has been developed and tested on mockups containing iron gall inks. The protective action arisingfrom the combined treatment was evaluated by performing cellulose viscosimetric degree of polymer-ization (DPv) and pH measurements on artificially aged systems. Scanning electron microscopy equippedwith energy dispersive X-ray spectroscopy (SEM-EDX) was used for the evaluation of calcium distributionfrom the deacidification agent within samples cross section. Determinations of DPv clearly showed thatthe degradation of untreated inked paper was significantly slowed down by the combined treatment. Themethod was also tested on original manuscripts from 16th and 18th century. SEM-EDX maps showedthat the applied treatment, which raised the pH to an appropriate value, is homogenously distributedover the treated surfaces.