Art historians, conservators and restorers, have traditionally shown interest in knowingthe nature of the pigments of the art works they study. On the one hand, they areespecially interested in knowing how artworks are made. They search the presence ofcertain materials with purposes of expertise (to propose attributions or just toestimate their age). On the other hand, in the field of conservation there are otherinterests that prevail: to identify the pigments and their composition canhelp to guessthe possible problems that a piece may have, or it can serve to choose the propersolutions for such pathologies. However, when studying paintings, both kinds ofprofessionals have to deal with limitations. Neither is always possible to co-work withchemicals or physicals –who can led the identification of materials with XRF, RAMAN,spectrometers or other instruments–, nor they have budget or resources to carry outsuch analysis. Instead, both art historians and conservators work frequently with thephoto camera, which, at least, could help in some way to identify pigments. In the lastyears, several studies dealing with multiband imaging applied to works of art haveachieved successfully results with that purpose (Herrero et al. 2018: 5-15); (Cosentino2014: 2-12). Multiband analysis consists of series of images in different regions of thespectrum. A full spectrum camera is commonly used as main device due to itspossibilities to work within the UV range and also within the IR (300-1100nm). Themultiband analysis (MBTI) consists of a series of photographs, UVR, UVF, VIS, IR, IRR,IRF, IRFC, and, excluding the IRR, all the rest are done with that same device. 24Even ifthe diverse techniques which MBTI comprises have their own independent value,(specially IRFC), when they are used together they provide much more information, bycomparing the many results. (Poldi; Villa, 2006: 127-137); (Cosentino 2014; 2016: 4-5)This study proposes the observation of the behaviour of 20 historical pigments anddyes throughout the spectrum, in the different images of MBTI. Some have been usedsince Antiquity, and others incorporated progressively on the palette of painters, untilthe 18th century. They have been bound with oil, painted on a surface prepared withchalk-glue ground, similar to traditional preparation. They all have been previouslycharacterized with RAMAN. Then, they have been imaged in VIS, IR and UV ranges. Inorder to calibrate colours a modified AIC target has been used (Cosentino 2014: 3).Although the system can not be considered precise, (and should be backed with somephysical or chemical analysis before extracting definitive conclusions) it can help, at least to a first approach. It is a very economical, visual-based, non-invasive fast system.It serves to check the presence of some materials (in some cases, the system proves tobe almost infallible). Hence, with very basic equipment, interesting results for arthistorians and conservators can be obtained.
Riconoscere dal colore. Pigmenti e coloranti dell'età moderna nell'analisi multibanda dei dipinti: uno strumento visivo per gli storici dell'arte e i conservatori
Paola Artoni
2019-01-01
Abstract
Art historians, conservators and restorers, have traditionally shown interest in knowingthe nature of the pigments of the art works they study. On the one hand, they areespecially interested in knowing how artworks are made. They search the presence ofcertain materials with purposes of expertise (to propose attributions or just toestimate their age). On the other hand, in the field of conservation there are otherinterests that prevail: to identify the pigments and their composition canhelp to guessthe possible problems that a piece may have, or it can serve to choose the propersolutions for such pathologies. However, when studying paintings, both kinds ofprofessionals have to deal with limitations. Neither is always possible to co-work withchemicals or physicals –who can led the identification of materials with XRF, RAMAN,spectrometers or other instruments–, nor they have budget or resources to carry outsuch analysis. Instead, both art historians and conservators work frequently with thephoto camera, which, at least, could help in some way to identify pigments. In the lastyears, several studies dealing with multiband imaging applied to works of art haveachieved successfully results with that purpose (Herrero et al. 2018: 5-15); (Cosentino2014: 2-12). Multiband analysis consists of series of images in different regions of thespectrum. A full spectrum camera is commonly used as main device due to itspossibilities to work within the UV range and also within the IR (300-1100nm). Themultiband analysis (MBTI) consists of a series of photographs, UVR, UVF, VIS, IR, IRR,IRF, IRFC, and, excluding the IRR, all the rest are done with that same device. 24Even ifthe diverse techniques which MBTI comprises have their own independent value,(specially IRFC), when they are used together they provide much more information, bycomparing the many results. (Poldi; Villa, 2006: 127-137); (Cosentino 2014; 2016: 4-5)This study proposes the observation of the behaviour of 20 historical pigments anddyes throughout the spectrum, in the different images of MBTI. Some have been usedsince Antiquity, and others incorporated progressively on the palette of painters, untilthe 18th century. They have been bound with oil, painted on a surface prepared withchalk-glue ground, similar to traditional preparation. They all have been previouslycharacterized with RAMAN. Then, they have been imaged in VIS, IR and UV ranges. Inorder to calibrate colours a modified AIC target has been used (Cosentino 2014: 3).Although the system can not be considered precise, (and should be backed with somephysical or chemical analysis before extracting definitive conclusions) it can help, at least to a first approach. It is a very economical, visual-based, non-invasive fast system.It serves to check the presence of some materials (in some cases, the system proves tobe almost infallible). Hence, with very basic equipment, interesting results for arthistorians and conservators can be obtained.
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