Performance Evaluation of Hybrid Formulations Consisting of Antioxidant and Crosslinking Agents for the Treatment of Acid Degradation in Historic Vegetable-Tanned Leathers

Abstract

This study investigated the performance of several new formulations for the treatment of acid degradation in historic leathers made with condensed tannins. This investigation was performed for four formulations consisting of collagen-stabilizing agents (oxazolidine E, resorcinol, nano alumina, and nano silica) and an antioxidant agent (Songnox 1010) in the acidic environment. The compounds were applied to 19th-century leathers with a brush. The properties of the leathers before and after treatment and accelerated aging were determined by measuring pH, shrinkage temperature, and color and conducting ATR-FTIR and FORS. For accelerated aging, the samples were exposed to an atmosphere with 95ppm SO2, 40°C, and 51% relative humidity for 14 days. The results showed that all of the tested formulations slowed down the acid degradation process. The combined use of collagen stabilizing agents provided good treatment properties and adding Songnox 1010 antioxidant agent to this combination further enhanced the effect of treatment. Among the tested formulations, the one containing oxazolidine+resorcinol+nano alumina+S1010 provided the best properties for controlling acid degradation.