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Suitable classification of mortars from ancient Roman and Renaissance frescoes using thermal analysis and chemometrics.

Tomassetti M, Marini F, Campanella L, Positano M, Marinucci F - Chem Cent J (2015)

Bottom Line: PCA allowed differentiating the two kinds of mortars (Roman and Renaissance frescoes), and evidenced how the ancient Roman samples are richer in binder (calcium carbonate) and contain less filler (aggregate) than the Renaissance ones.It was also demonstrated how the coupling of thermoanalytical techniques and chemometric processing proves to be particularly advantageous when a rapid and correct differentiation and classification of cultural heritage samples of various kinds or ages has to be carried out.Graphical abstractPCA analysis of TG data allows differentiating mortar samples from different ages (Roman era and Renaissance).

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Rome, "La Sapienza" P.le A. Moro 5, I-00185 Rome, Italy.

ABSTRACT

Background: Literature on mortars has mainly focused on the identification and characterization of their components in order to assign them to a specific historical period, after accurate classification. For this purpose, different analytical techniques have been proposed. Aim of the present study was to verify whether the combination of thermal analysis and chemometric methods could be used to obtain a fast but correct classification of ancient mortar samples of different ages (Roman era and Renaissance).

Results: Ancient Roman frescoes from Museo Nazionale Romano (Terme di Diocleziano, Rome, Italy) and Renaissance frescoes from Sistine Chapel and Old Vatican Rooms (Vatican City) were analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). Principal Component analysis (PCA) on the main thermal data evidenced the presence of two clusters, ascribable to the two different ages. Inspection of the loadings allowed to interpret the observed differences in terms of the experimental variables.

Conclusions: PCA allowed differentiating the two kinds of mortars (Roman and Renaissance frescoes), and evidenced how the ancient Roman samples are richer in binder (calcium carbonate) and contain less filler (aggregate) than the Renaissance ones. It was also demonstrated how the coupling of thermoanalytical techniques and chemometric processing proves to be particularly advantageous when a rapid and correct differentiation and classification of cultural heritage samples of various kinds or ages has to be carried out. Graphical abstractPCA analysis of TG data allows differentiating mortar samples from different ages (Roman era and Renaissance).

No MeSH data available.


PCA on all the data reported in Table 1 after autoscaling. Loadings plot.
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Fig6: PCA on all the data reported in Table 1 after autoscaling. Loadings plot.

Mentions: Indeed, results show that the two groups of samples (i.e. ancient Roman and Renaissance frescoes) are clearly separated along the first principal component, the differentiation being related in particular to the mass loss due to the carbonate decomposition step and the percentage of final TG residue at 1000°C, as can be observed in the loadings represented in Figure 6. In particular, the first principal component is mostly made of the contribution of the third identified thermogravimetric step, corresponding to the carbonate decomposition (both in terms of mass loss – with a high negative loading - and peak temperature, which has a positive value), together with the residue at 1000°C and the mass loss in the second TG step (both with positive loadings). On the other hand, the second principal component is mainly characterized by the moisture content and the peak temperature of the second TG step, the former with positive and the latter with negative loadings, respectively. This fully confirms the preliminary considerations made on the data reported in Table 1. The loading representation showed that also the mass loss of the organic traces exerts however a certain role in the separation of different samples along the first principal component. It is also interesting to note that, in the case of the Renaissance samples, three subclusters can readily be identified, which refer to the three different frescoes from which the samples were obtained. In this case, inspection of the loadings (Figure 6) confirms that the separation into three subclusters corresponding to the samples coming from the three different Renaissance frescoes, which occurs along the second PC, is essentially due to the DTG peak temperature of the organic substance loss step and to the moisture mass loss.Figure 6


Suitable classification of mortars from ancient Roman and Renaissance frescoes using thermal analysis and chemometrics.

Tomassetti M, Marini F, Campanella L, Positano M, Marinucci F - Chem Cent J (2015)

PCA on all the data reported in Table 1 after autoscaling. Loadings plot.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4414380&req=5

Fig6: PCA on all the data reported in Table 1 after autoscaling. Loadings plot.
Mentions: Indeed, results show that the two groups of samples (i.e. ancient Roman and Renaissance frescoes) are clearly separated along the first principal component, the differentiation being related in particular to the mass loss due to the carbonate decomposition step and the percentage of final TG residue at 1000°C, as can be observed in the loadings represented in Figure 6. In particular, the first principal component is mostly made of the contribution of the third identified thermogravimetric step, corresponding to the carbonate decomposition (both in terms of mass loss – with a high negative loading - and peak temperature, which has a positive value), together with the residue at 1000°C and the mass loss in the second TG step (both with positive loadings). On the other hand, the second principal component is mainly characterized by the moisture content and the peak temperature of the second TG step, the former with positive and the latter with negative loadings, respectively. This fully confirms the preliminary considerations made on the data reported in Table 1. The loading representation showed that also the mass loss of the organic traces exerts however a certain role in the separation of different samples along the first principal component. It is also interesting to note that, in the case of the Renaissance samples, three subclusters can readily be identified, which refer to the three different frescoes from which the samples were obtained. In this case, inspection of the loadings (Figure 6) confirms that the separation into three subclusters corresponding to the samples coming from the three different Renaissance frescoes, which occurs along the second PC, is essentially due to the DTG peak temperature of the organic substance loss step and to the moisture mass loss.Figure 6

Bottom Line: PCA allowed differentiating the two kinds of mortars (Roman and Renaissance frescoes), and evidenced how the ancient Roman samples are richer in binder (calcium carbonate) and contain less filler (aggregate) than the Renaissance ones.It was also demonstrated how the coupling of thermoanalytical techniques and chemometric processing proves to be particularly advantageous when a rapid and correct differentiation and classification of cultural heritage samples of various kinds or ages has to be carried out.Graphical abstractPCA analysis of TG data allows differentiating mortar samples from different ages (Roman era and Renaissance).

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Rome, "La Sapienza" P.le A. Moro 5, I-00185 Rome, Italy.

ABSTRACT

Background: Literature on mortars has mainly focused on the identification and characterization of their components in order to assign them to a specific historical period, after accurate classification. For this purpose, different analytical techniques have been proposed. Aim of the present study was to verify whether the combination of thermal analysis and chemometric methods could be used to obtain a fast but correct classification of ancient mortar samples of different ages (Roman era and Renaissance).

Results: Ancient Roman frescoes from Museo Nazionale Romano (Terme di Diocleziano, Rome, Italy) and Renaissance frescoes from Sistine Chapel and Old Vatican Rooms (Vatican City) were analyzed by thermogravimetry (TG) and differential thermal analysis (DTA). Principal Component analysis (PCA) on the main thermal data evidenced the presence of two clusters, ascribable to the two different ages. Inspection of the loadings allowed to interpret the observed differences in terms of the experimental variables.

Conclusions: PCA allowed differentiating the two kinds of mortars (Roman and Renaissance frescoes), and evidenced how the ancient Roman samples are richer in binder (calcium carbonate) and contain less filler (aggregate) than the Renaissance ones. It was also demonstrated how the coupling of thermoanalytical techniques and chemometric processing proves to be particularly advantageous when a rapid and correct differentiation and classification of cultural heritage samples of various kinds or ages has to be carried out. Graphical abstractPCA analysis of TG data allows differentiating mortar samples from different ages (Roman era and Renaissance).

No MeSH data available.