Hand-working with a fine, medium-sized or large Chisel is the oldest surface treatment for Etna lava stone and was carried out with a tip or drill and mallet by skilled manual operators called stone-cutters and furthermore, in our family, by dad and granddad.
This deals with the hammering of stone with chisels of various sizes which create alternating areas of depressions and relief on the surface of the stone; the final result mainly depends on the degree of chiseling requested, choosing between “fine” or fine chiseling, “medium” or medium-chiseling and “large” or large-chiseling where the relief effect gradually increases.
Talking about chiseling, it is appropriate to dwell on a technical aspect, which is for the most part underestimated: the characteristics of structure, material and porosity of the Basalt extracted from our quarry makes it well able to endure more or less well, the treatment of impact which notoriously constitute a stress of certain relevance.
Normally, use of materials which are chiseled call for an increased thickness to allow for the strikes subjected to by working on the surface.
However, the said increase or thickness may not generate any advantage because according to the type of material extracted and the presence of products coming from different quarries, what is underestimated is the weakness, on a sub-millimetre scale, of the intimate structure of the rock which reacts to being worked on with secondary porous openings, otherwise not present, and the creation of accessibility to porosity already present and otherwise not accessible. This is detrimental and, certainly responsible for diminished mechanics/dynamics and physical resistance in many types of basalt which the usual laboratory tests do not show but which on-site testing such as in road paving demonstrates with dramatic criticality.