Evaluation of carbon-based nanostructures suitable for the development of black pigments and glazes

Five different carbon-based samples were chosen for the fabrication of black pigments and glazes: historical 'unknown' wood charcoal, graphite, tailored graphitized soot, as-prepared multi-walled carbon nanotubes (MWCNTs) and purified MWCNTs. Ceramic glazes with carbon pigments were prepared with Pb3O4 and SiO2 in molar ratio of 2.85:1.9 and using 5 wt. % of pigment at 900 degrees C. The black pigments and glazes were characterized by scanning electron microscopy (SEM), optical microscopy, diffuse reflectance spectroscopy and contact angle measurements. International Commission on Illumination (CIE) parameters L*, a* and b* (CLELab-parameters) of the samples were also determined. It was demonstrated that nanostructured carbon pigments showed better black colour and higher quality of black ceramic glaze. Our investigation let us to conclude that these results possibly were affected by initial microstructure of applied carbon derivatives. The obtained nanostructured carbon black pigments could be successfully used for artefact restoration.