Application of Mg(OH)2 nanosheets for conservation and restoration of precious documents and cultural archives

Abstract

Magnesium hydroxide (Mg(OH)2) nanosheets were explored as an effective material for the restoration and conservation of paper-based cultural archives and compared with the commonly used Ca(OH)2 nanoparticles. The (Mg(OH)2) nanosheets were applied to filter paper as a reference, as well as to new and old paper samples. The effectiveness of Mg(OH)2 nanosheets was evaluated by (i) a pH test of the surface and the bulk extracts, (ii) measuring the alkaline reserve and correlating it with the enhancement in life expectancy, and (iii) in terms of mechanical strength. The alkaline reserve test indicated an increase in the alkaline buffer, which resulted in markedly reduced acidic content of the samples. It was inferred from the improved properties that Mg(OH)2 nanosheets coated the paper as a lamination sheet and protected it as the first line of defense against acidic environmental attack. Moreover, its presence within the paper acted as an alkaline reserve and also as reinforcement in the form of an inorganic nanosheet. The results suggest that the nanosheets are an innovative, compatible, and efficient material for the consolidation and restoration of old and new paper samples.