Preservation of bread-made museum collections by coating technology

Bread-made artifacts are the products of an ancient creative tradition in some parts of Sardinia. While early objects were intended for pagan events (e.g., grain harvest), later artworks were specifically made for Catholic celebrations, such as Christmas and Easter. Unfortunately, the cultural heritage linked to these objects is endangered by Sitophilus granarius (L.), a tiny insect that causes irreparable damage, such as ruptures and galleries through an intense boring action. In this work, we have evaluated the potential for the coating technology to protect bread-made artifacts from entomatic attack. Within this scope, a nanocomposite coating and an active coating were prepared, and the coated objects were characterized in terms of optical, mechanical, and insect-resistant properties. Overall, the deposition of the coating did not negatively impact the appearance of the objects, although some differences were detected instrumentally in terms of color and gloss. In addition, both coating formulations decreased the Young's modulus of the samples subjected to a flexural test, which was attributed to the plasticizing effect of the poly-methyl methacrylate and deltamethrin. The entomatic tests revealed that the nanocomposite coating was the most effective for preventing the wheat weevil attack, with no damages detected on the samples and high mortality of the insects due to hunger. The approach proposed here could be successfully extended to other art objects (e.g., museum collections) susceptible to insect attacks.