Colorimetric and spectral data analysis of consolidants used for preservation of medieval plasterwork

Martínez, Miguel Á.; Calero, Ana Isabel; Valero, Eva M.

doi:10.1016/j.culher.2019.08.010

Cited by 5 publications

(6 citation statements)

References 21 publications

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“…Hyperspectral images of the probes were captured before and after the cleaning process using a hyperspectral imaging scanner model Resonon Pika L. This scanner yields hyperspectral images roughly in the range from 383 to 1016 nm, with 4.1 nm spectral resolution. The system is calibrated for illumination and flat field correction, so the hyperspectral cubes contain pixel-wise spectral reflectance information of the probes [ 17 , 18 , 36 ].…”

Section: Methodsmentioning

confidence: 99%

“…Analysis methods based on spectral images have been successfully applied in previous studies for restoration and cultural heritage applications. For example, in [ 17 ], the effect of different consolidants used in medieval plasterwork is analyzed. In [ 18 ], the effect of ageing of the different varnish materials is studied on paper samples.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Cleaning Processes Using Colorimetric and Spectral Data for the Removal of Layers of Limewash from Medieval Plasterwork

Martínez-Domingo

Castillo

García

et al. 2020

Sensors

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In the cultural heritage preservation of medieval buildings, it is common to find plaster walls covered in lime, which previously were painted in polychromy. The conservation interventions usually try to remove the whitewash, whilst maintaining the original color of the painted wall as much as possible. However, there is no agreement on which cleaning technique best preserves the original appearance of the colored plaster. Different pigments found below the lime layer may behave differently depending on the cleaning technique used. Usually, colorimetric or photometric area-based measurements are carried out to study the color of the cleaned areas to compare with their original color, obtained from pre-made plaster probes. However, this methodology fails when the mean color difference is not enough to fully characterize the changes in texture and color appearance. This study presents a set of experiments carried out using two different pigments (cinnabar and malachite) covered with lime, and treated with nine different cleaning techniques on plaster probes prepared according to medieval techniques. We have studied the effect of the cleaning process on the color and the homogeneity of the samples using a hyperspectral imaging workflow. Four different analysis methods are presented and discussed. Our results show that the proposed analysis is able to provide a much more comprehensive and diversified characterization of the quality of the cleaning method compared to the commonly used colorimetric or photometric area-based measurements.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of Cleaning Processes Using Colorimetric and Spectral Data for the Removal of Layers of Limewash from Medieval Plasterwork

Martínez-Domingo

Castillo

García

et al. 2020

Sensors

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“…necessary evaluation indices for protective coating materials or metho heritage [36]. It is commonly conducted by the determination of colo ally, the threshold of color difference is 5.0 in the conservation of cu The color difference of the bone samples in the present study varied b (Figure 12), which are all below 5.0, so are acceptable [38].…”

Section: Resultsmentioning

confidence: 65%

“…Thus, the newly generated CSD phase can work as both a filling and reinforcing agent of weak bones. The change in appearance is one of the necessary evaluation indices for protective coating materials or methods used on cultural heritage [36]. It is commonly conducted by the determination of color difference.…”

Section: Resultsmentioning

confidence: 99%

Consolidation of Fragile Oracle Bones Using Nano Calcium Sulfate Hemihydrate as a Protectant

Liu

et al. 2022

Coatings

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Herein, a nano calcium sulfate hemihydrate suspension in an alcohol solvent was prepared and explored as a novel protectant for fragile oracle bones. The consolidation method involved first introducing the suspension and then adding water into the bones. Through this method, cohesive calcium sulfate dihydrate formed in the bones and can act as a reinforcing material. The protective effect was studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), hardness, porosity, and color difference determination. The results showed that such consolidation increased the strength of the bone samples significantly, and only slightly changed the appearance and porosity of the bone samples, indicating a good prospect for applying nano calcium sulfate hemihydrate in the conservation of indoor fragile bone relics.

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“…New portable and fast imaging devices, together with powerful computers, enable researchers to retrieve valuable information from spectral images. Within the field of spectral imaging, applications related to art and cultural heritage are increasingly taking advantage of this promising technology [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Spectral Image Processing for Museum Lighting Using CIE LED Illuminants

Martínez-Domingo

Melgosa

Okajima

et al. 2019

Sensors

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This work presents a spectral color-imaging procedure for the detailed colorimetric study of real artworks under arbitrary illuminants. The results demonstrate this approach to be a powerful tool for art and heritage professionals when deciding which illumination to use in museums, or which conservation or restoration techniques best maintain the color appearance of the original piece under any illuminant. Spectral imaging technology overcomes the limitations of common area-based point-measurement devices such as spectrophotometers, allowing a local study either pixelwise or by selected areas. To our knowledge, this is the first study available that uses the proposed CIE (Commission Internationale de l’Éclairage) light-emitting diode (LED) illuminants in the context of art and heritage science, comparing them with the three main CIE illuminants A, D50, and D65. For this, the corresponding colors under D65 have been calculated using a chromatic adaptation transform analogous to the one in CIECAM02. For the sample studied, the CIE LED illuminants with the lowest average CIEDE2000 color differences from the standard CIE illuminants are LED-V1 for A and LED-V2 for D50 and D65, with 1.23, 1.07, and 1.57 units, respectively. The work studied is a Moorish epigraphic frieze of plasterwork with a tiled skirting from the Nasrid period (12th–15th centuries) exhibited in the Museum of the Alhambra (Granada, Spain).

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Colorimetric and spectral data analysis of consolidants used for preservation of medieval plasterwork

Cited by 5 publications

References 21 publications

Evaluation of Cleaning Processes Using Colorimetric and Spectral Data for the Removal of Layers of Limewash from Medieval Plasterwork

Evaluation of Cleaning Processes Using Colorimetric and Spectral Data for the Removal of Layers of Limewash from Medieval Plasterwork

Consolidation of Fragile Oracle Bones Using Nano Calcium Sulfate Hemihydrate as a Protectant

Spectral Image Processing for Museum Lighting Using CIE LED Illuminants

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