Surface investigations of old book paper treated with hydroxyapatite nanoparticles

Today, modern chemicals, as nanomaterials, are essential to preserve the worldʹs artistic and cultural heritage. A new restoration method for old book paper restoration, based on a special hydroalcoholic suspension of hydroxyapatite nanoparticles, have been presented and discussed in this paper. This new method is based on the nanoparticles properties to penetrate into the materials network, to adhere to them, covering the damaged area and consolidating the damaged region. Several methods of instrumental chemical analysis have been employed: DLS, in order to determine the size of the synthesized nanoparticles and SEM, AFM spectral techniques to study the nanoparticles interaction with the paper support. Also, pH and change in yellowness of the restored surface have been evaluated, too. The influence of accelerated light aging has also been evaluated and discussed in this study, taking into acount that the aging of the document paper is an unavoidable process, difficult to study.