Virtues of Giambologna from Grimaldi Chapel Archaeometric Characterisation Part II: ‘Artistic’ and Natural Patinas VALERIA BONGIORNO, 1,2,4 PAMELA GROSSO, 2 PAOLO PICCARDO, 2 LAURO G. MAGNANI, 3 and MARIA M. CARNASCIALI 2 1.—Consiglio Nazionale delle Ricerche - Istituto per l’Energetica e le Interfasi (CNR IENI), Via De Marini 6, 16149 Genoa, Italy. 2.—Dipartimento di Chimica e Chimica Industriale (DCCI), Univ- ersita ` degli Studi di Genova, Via Dodecaneso 31, 16146 Genoa, Italy. 3.—Dipartimento di Italia- nistica, romanistica, antichistica, arti e spettacolo (DIRAAS), Universita ` degli Studi di Genova, Via Balbi 2, 4 e 6, 16126 Genoa, Italy. 4.—e-mail: valeria.bongiorno@gmail.com The scientific investigation on metal artwork is meant to expand the knowl- edge regarding the technical skills developed by artists in sculpture manu- facturing. Moreover, all the gathered data support the speculation about the motivations behind the choices of certain material or a specific casting and/or finishing method (e.g., aesthetic, economic or technical reasons, or both) and give fundamental information for planning adequate restoration interven- tions. The subject of this study is the Virtues sculptural group made at the end of the XVI century by Giambologna to decorate the Grimaldi Chapel in the church of San Francesco di Castelletto (Genoa, Italy). Six life-size statues depicting Charity, Justice, Hope, Fortitude, Faith, and Temperance (i.e., the artwork discussed in this article); seven bas-reliefs; and six winged repre- sentations of putti are what remains of the original monumental project. Different micro-invasive analytical techniques (scanning electron microscopy and energy dispersive x-ray spectroscopy, SEM–EDS; micro-Raman Spec- troscopy, lRS; gas chromatography–mass spectrometry, GC–MS) were ap- plied to determine the chemical nature and the state of conservation of the ‘‘artistic’’ and natural patinas visible on the Virtues surfaces. Some patination tests were performed taking into account the collected analytical data and the indications provided by the scientific literature and the historical documents. The combination of the results obtained through the scientific investigations and the experimental work allowed for supposing the materials and the patination technique selected by the artist to adorn the sculptures and pro- viding indications for the correct conservation of the six sculptures. INTRODUCTION The complete characterization of metal artworks includes the identification of their constitutive mate- rials: metal or alloy, natural and ‘‘artistic’’ patinas. Natural patina is more correctly called ‘‘corro- sion’’ and is the consequence of the aging of a metallic artifact in contact with a specific environ- ment; on the other hand, ‘‘artistic’’ patina is a coating applied intentionally by the artist, a spe- cialist or a foundry man to achieve specific color effects, as well as to homogenize the treated surface and hide, when necessary, casting defects. 1–3 Generally, the ‘‘artistic’’ patination is an opera- tion based on the cold or hot application of chemicals (e.g., iron- or copper-based salts). 4–7 A variation in respect to the aforementioned procedure is represented by the use of organic compounds, those frequently called ‘‘var- nishes’’ or ‘‘lacquers,’’ in the art-historical literature. 8,9 These finishing methods, together with the appli- cation of wax to protect and highlight the produced coatings, have been used since antiquity and, with appropriate improvements, are still in vogue nowadays. 5,6,10 JOM, Vol. 68, No. 8, 2016 DOI: 10.1007/s11837-016-1950-x Ó 2016 The Minerals, Metals & Materials Society 2222 (Published online May 17, 2016)