A good deal of the findings of archaeological mural paintings are in land excavations, a factor which conditions the state of repair in which they are found. The formation of compact and stubborn carbonate crusts on the surface of objects proceeding from an alkaline underground atmosphere is commonly found. These prevent the object’s proper visualisation, something which is particularly negative in the case of a pictorial work. This article covers a study made on different cleaning treatments intended for the elimination of these carbonate concretions. The study consisted of a theoretical bibliographic review of the matter and the execution of a practical example, experimenting and comparing several selected treatments on a test piece created for this purpose.