Polymer Treatments for Stone Conservation: Methods for Evaluating Penetration Depth

Abstract This study examines the measurement of penetration depths for three polymer treatments for stone conservation—acrylic, partially fluorinated acrylic, and siloxane polymers. The treatments were tested on three types of calcareous stones of increasing porosity, widely present in historic architecture and monuments in Italy. Various approaches were explored, including direct determination with various Fourier transform infrared spectroscopic techniques (micro-attenuated total reflection, diamond cell transmission, and hyphenated with thermogravimetry) as well as indirect methods such as static angle measurements. Micro-attenuated total reflection on cross sections of treated specimens proved to be a particularly powerful technique for detection of polymers, with fairly good spatial resolution and sensitivity. The degree of penetration of polymers inside the porous matrix of stone is an important parameter when evaluating the efficacy and durability of treatments. Therefore, developing reliable testing methods for determining penetration depth is crucial.

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