Sardinia is an ancient island where it is possible to find signs and symbols, decorative engraved and colored traces of men and history. Egyptian blue was used in blue paints while in black paints it was mixed with carbon and bone black pigments. In red paints, hematite and red ochre are frequently associated with ilmenite, a typical volcanic mineral. The alteration of green earth and other iron-containing pigments are likely responsible for the discolouration of the original hues. The hues of vegetal decorations were obtained using green earth, sometimes Egyptian blue mixed with yellow ochre, carbon and bone blacks, and orpiment. The results confirmed the use of a limited number of pigments, usually applied with fresco technique, although in many cases the stratigraphy of the painted layer showed morphology of mezzo fresco technique, but no organic binders were found. A multi-analytical approach was performed on 32 funerary slabs (6th - 3rd century BCE), currently located at the National Archaeological Museum of Paestum (Italy) using both polarized light microscopy and environmental scanning electron microscopy equipped with energy dispersive X-ray spectrometer, micro X-ray fluorescence, micro Raman spectroscopy, Fourier Transform Infrared spectroscopy and powder X-ray diffraction. This artificial pigment, widely employed as opacifier both in ancient glass and glaze covering clay objects, was found in the wall paintings, regardless of the colour, supporting the hypothesis of an intentional addition of calcium antimonate to the pigments and the involvement of ceramic painters. The identified pigments were red and yellow ochre, green earth, Egyptian blue, carbon black and lime white all of them belonged to the so-called austere pigment, which is quite common in Roman wall paintings.ĭuring a restoration and diagnostic campaigns carried out on Paestum funerary slabs belonging to the Lucanian funerary art, calcium antimonate (CaSb2O6) was detected for the first time in the pictorial layers. The wall paintings were mainly executed using the fresco technique, while for some details secco was used. This is in accordance with the drilling resistance measurement system test (DRMS), confirming that layers with angular carbonate grains are harder than those with addition of rounded silicate ones, due to the good packing effect. Furthermore, the results of mercury intrusion porosimetry showed that mortar layers consisting of carbonate grains exhibited lower porosity with respect to layers with mainly silicate grains, which is attributed to the angular shapes of carbonate aggregate. The investigated samples were divided into several groups based on similar thicknesses of the mortar layer, the binder colour and the composition of an aggregate. The mineralogical–petrographic compositions of the mortars were determined by means of optical microscopy and FT–IR spectroscopy. Fragments of wall paintings consist of up to three preserved mortar layers. This study concerns the investigation of mortar layers and pigments of wall paintings from the Roman town of Emona (Ljubljana, Slovenia). The lack of yellow colourants in China tomb murals is more likely to be a cultural rather than technological choice. Interestingly, Chinese craftspeople had a long history of interacting with the iron- or lead-bearing minerals related to these yellow pigments, and there seem no critical technological barriers against extracting and using yellow by the Tang dynasty. Compared to geothite, vanadinite is even more rarely found in tomb mural painting and fewer reports have been mentioned, which led us to think about the accessibility of such pigment.

The results show that the yellow pigment in three tombs is goethite (FeO), whereas in a late Tang tomb is vanadinite (Pb53Cl). Multi-analytical approaches have been applied in this study, including chromaticity analysis, cross-section, polarizing microscopy, Raman spectroscopy, scanning electron microscopy with energy-dispersive spectrometry and X-ray diffraction. The recently discovered mural paintings at Xi'an (dated to the Tang dynasty, 618–907 ce) offer fresh materials for characterization of yellow pigments, which can be potentially useful for filling the gap of the yellow pigments. Yellow colourants appear to have been rarely employed for tombs mural paintings in ancient China.

Lod mosaics at columbus museum of art