Sustainable stone protection using a zein-based coating
In a recent work, the efficiency of an ecofriendly 5% solution of zein in DMSO was evaluated as protective material for stone. The solution was sprayed on 5 × 5 × 1 cm slabs of Serena stone, a sandstone widely used in Florentine architecture. The obtained coating turned out to be hydrophobic, showing a Water Contact angle of around 120°, while a reduction of 8.4% in water uptake was observed during 15 days.
SEM and profilometer analyses stated that the zein coating application resulted in the formation of a compact film on the stone’s surface with a continuous structure characterised by micro-scale roughness. A mechanism of hydrophobic surface formation, in which both the roughness and the solvent’s evaporation style are believed to play a significant role. Accelerated aging tests indicated a good resistance to aging in terms of hydrophobicity and colour variations.
According to the researchers, this sustainable approach can be easily scaled and may represent a valuable alternative to the most common synthetic treatments used nowadays in stone protection.
The study has been published in Progress in Organic Coatings, Volume 159, October 2021.