Synthetic antioxidants as iron gall ink corrosion inhibitors in historical manuscripts.

• Synthetic antioxidants were used here to control the corrosion of iron gall ink in papers. • Optimum amount of each antioxidant was determined using the electrochemical method. • BHA alone and in combination with BHT and TBHQ showed the best performance. Iron gall ink is one of the oldest inks used in many countries. Acid hydrolysis and oxidation are two important factors in the corrosion of iron gall ink, which cause the degradation of cellulose. Antioxidants can control the oxidation process by scavenging the radicals. In this study, three synthetic antioxidants (butylated hydroxyl anisole (BHA), butylated hydroxyl toluene (BHT), and tert‑butyl hydroquinone (TBHQ)) used in the food industry were selected to control the oxidation of iron ink in cellulose papers. The effectiveness of these antioxidants in reducing paper degradation was studies individually and in combination with each other. The long-term effect of these antioxidants on paper samples was evaluated after accelerated aging by heat and moisture, and the changes occurring during aging were studied by measuring the tensile strength, pH, color, and oxidation rate of the paper samples. To control the acid hydrolysis together with oxidation process, inked paper samples were deacidified before coating them with antioxidants. The results show the positive effect of these antioxidants on the control of iron gall ink corrosion. Among these antioxidants, BHA alone and in combination with other antioxidants (BHA+BHT+TBHQ) and (BHA+TBHQ) showed better performance in preserving paper samples and BHT shows the lowest effect on control the degradation processes in paper. [ABSTRACT FROM AUTHOR]