Protective patinas applied on stony façades of historical buildings in the past

The ochre patina that covers the limestone façades of Palacio de Nuevo Baztán is composed of calcite, clay minerals, gypsum, quartz, potassium feldspar, alongside traces of calcium oxalates, calcium phosphates, iron oxides and hydroxides. It is a polistratified film, rich in Ca, Si, Al and P, as well as Mg, K, Fe and Cl. Results obtained indicate that the origin of the patina lies in a treatment applied on the stone in the past, consisting of a mixture of lime, gypsum, milk-derived compounds and inorganic earth pigments. This film has protected the stone on which it was applied, and should be preserved in any further stages of intervention on the stone façades.