Evaluation of the efficacy and durability of the "barium hydroxide method" after 40 years. Multi-analytical survey on the Crocifissione by Beato Angelico

The wall-painting Crocifissione by Beato Angelico in the convent of San Marco in Florence was subjected to a restoration campaign in 1970-1974. In that occasion the barium hydroxide method, a procedure properly designed for the restoration of sulphate polluted wall-paintings, was applied for the first time. After 40 years, a diagnostic campaign based on a multi-analytical approach combining non-invasive and micro-invasive techniques was planned and the results are here presented. Results allowed to reveal the painting palette as well as past restoration byproducts, and potentially active sulphation phenomena. The evaluation of the efficacy and durability of the barium hydroxide treatment is discussed.