Researchers investigating an ancient Greek vase dating from 450–440 BC have identified the probable use of gypsum in its distinctive white background. Until now little was known about the composition of the white slip used in these rare vessels, which featured in the funeral rituals of the elite.
The Perseus crater, exhibited at the Pietro Griffo archaeological museum in Agrigento, Italy, is a fine example of an Attic vase painted using the white ground technique – a comparable rarity next to the more famous red-figure ceramics produced in Athens around the same time. Artists would apply a white slip to the entire surface, allowing them to paint on figures with detailed contouring and vibrant colours.
The team used x-ray fluorescence (XRF) and total reflection Fourier-transform infrared spectroscopy (TR-FTIR) in their analysis of the vase, which they complemented with visible and ultraviolet light photography.
XRF data showed large amounts of calcium distributed over the entirety of the vase. The three probable sources considered were calcium carbonate, kaolinite (a mineral group of hydrous aluminium silicates) and calcium sulfates (eg gypsum). SmART_scan software using the XRF data produced maps that indicated the simultaneous presence of both calcium and sulfur over the entire white ground area, indicating that the artist used gypsum as the base for their white slip. TR-FTIR further ruled out the presence of kaolinite or calcium carbonate, strengthening the probability that gypsum was indeed the source.
In addition to the composition of the white ground, the team’s TR-FTIR spectra mapped majority and minority elements found in the painted figures themselves, and confirmed a probable firing temperature of 700–900°C, which corroborates what we previously knew about firing temperatures for Attic vases.
This article is open access
G Chirco et al, RSC Adv., 2022, 12, 4526 (DOI: 10.1039/d1ra06453c)
Watafiti wa zamani wa Ugiriki waliochunguza chupa ya kale ya 450 BC na 440 BC wamegundua uwezekano wa matumizi ya gypsum katika msingi wake wa kipekee mweupe. Hadi sasa, haijulikani sana jinsi nyuzi hizo nyeupe zilivyotumiwa katika ibada za mazishi za watu mashuhuri. Mlipuko wa Perseus, ulioonyeshwa katika makumbusho ya Pietro Griffo huko Agrigento, Italia, ni mfano mzuri wa chungu cha Attic kilichopakwa rangi kwa kutumia mbinu ya ardhi nyeupe - nadra inayoweza kulinganishwa na kauri maarufu za rangi nyekundu zilizotengenezwa huko Athens karibu wakati huo huo. Wasanii walitumia rangi nyeupe kwenye uso wote, na hivyo kuweza kuchora sanamu zenye umbo lenye kuvutia na rangi zenye kuvutia. Watafiti walitumia X-ray fluorescence (XRF) na jumla ya kutafakari Fourier-transform infrared spectroscopy (TR-FTIR) katika uchambuzi wao wa chupa, ambayo waliongeza na picha ya mwanga unaoonekana na ultraviolet. Takwimu za XRF zilionyesha kiasi kikubwa cha kalsiamu iliyosambazwa kwenye chupa nzima. Vyanzo vitatu vinavyowezekana vilivyochukuliwa vilikuwa calcium carbonate, kaolinite (kikundi cha madini ya silicates ya alumini ya maji) na sulfates za kalsiamu (kwa mfano gypsum). Programu ya SmartScan, kwa kutumia data ya XRF, ilitoa ramani ambazo zilionyesha uwepo wa kalsiamu na sulfuri wakati huo huo juu ya eneo lote la ardhi nyeupe, ikionyesha kwamba msanii alitumia gypsum kama msingi wa kuonekana kwao. "TRI-FTIR pia ilikataa uwepo wa kaolinite au calcium carbonate, ikiimarisha uwezekano kwamba gypsum ilikuwa kweli chanzo.""" Pamoja na muundo wa ardhi nyeupe, spectra ya timu ya TR-FTIR ilichora sehemu kubwa na ndogo zilizopatikana katika takwimu zilizopakwa rangi, na kuthibitisha joto la kuchoma la 700-900 ° C, ambayo inathibitisha kile tulichokuwa tukijua hapo awali juu ya joto la kuchoma kwa vyombo vya Attic. "Hii ni kwa sababu ya ""G. Chirco et al, RSC Adv. 2022, 124526, DOI 10.1039 (d1R0453c)."""