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Buzgar N., Apopei A. I., Buzatu A. (2009) - Romanian Database of Raman Spectroscopy (http://rdrs.uaic.ro)


PIGMENTS


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PNII - IDEI COD 2119/2008




Alexandru Ioan Cuza UniversityFaculty of Geography and Geology

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22 Hoiseşti L11

Sample image with black and red pigment
large image

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Raman spectrum of black pigment - Raman spectrum of Black Carbon (Isaiia)
Toggle Grid Toggle Coordinates Reverse Spectrum Download Raman spectrum of black pigment .spc or .txt
Legend: black pigment__ and Black Carbon (Isaiia)__ Download Raman spectrum of Black Carbon (Isaiia) standard .spc or .txt
Raman spectrum of red pigment - Raman spectrum of Hematite
Toggle Grid Toggle Coordinates Reverse Spectrum Download Raman spectrum of red pigment .spc or .txt
Legend: red pigment______ and hematite______ Download Raman spectrum of hematite standard .spc or .txt
Interpretation of the black and red pigment Raman spectra

The red pigment studied contains hematite and, more frequently, quartz. The Raman spectra recorded on fine sherds from Hoiseşti and Scânteia are very similar and present the main bands of hematite. The diffuse shape of the Raman bands is caused by the fine granulation of hematite. Also, this is confirmed by high intensity peaks in the 200-300 cm-1 region and a low intensity at 1320 cm-1, which is the most intense Raman band of hematite in large crystals (Zoppi et al., 2008; Buzgar et al., 2009).

The presence of quartz is proved by the most intense band at ~465 cm-1

Quartz gives a Raman signal which is more intense than that of hematite, therefore hematite bands are less obvious in the Raman spectra.

The presence of both hematite and quartz in the red pigment excludes the use of Fe oxyhydroxides as pure red pigment. For the red color, red clay, washed several times, a process that enriched the clay with Fe oxyhydroxides (+quartz), was used. This known process is used even nowadays by pottery artisans. The source of this clay is not a special issue, as it is commonly found interbeded throughout sedimentary deposits of the Moldavian Platform.

For the raw black ceramic from Hoiseşti (and this sample from Scânteia), the paste used was a clay rich in organic substance. Through the firing process, the organic substance turned into black carbon. The Raman spectra of these samples clearly indicate the presence of black carbon, being similar to the spectrum of a black ceramic sample from Isaiia (Precucuteni culture).

References

• BUZGAR N., BODI G., AŞTEFANEI D., BUZATU A. (2010) - The Raman study of white, red and black pigments used in Cucuteni Neolithic painted ceramics. Analele Stiintifice ale Universitatii “Al. I. Cuza” - Iasi, Tome 56, issue 1 [link]

• Zoppi, A., Lofrumento, C., Castellucci, E.M., Sciau, Ph., 2008. Al-for-Fe substitution in hematite: the effect of low Al concentrations in the Raman spectrum of Fe2O3. Journal of Raman Spectroscopy, 39, 40-46.