These are typically combinations of acids and corrosive agents such as chlorides but are not available as warranted systems with technical support. It is possible to apply a chemical treatment to the surface of the steel to encourage rapid development of a corroded surface, resembling the appearance of the naturally aged patina. This means that the noticeable quantity of that compound found in the patina of the Harpocrate body is not the result of corrosion but more probably due to the intentional patination process.įig. It is interesting to mention that nantokite is not very common as a normal corrosion product. The distinction between intentionally patinated areas and corroded areas is then clear. the inkpot top), the corrosion products are, as expected, enriched in tin and lead. When the substrate is brass (inkpot body) or a quaternary alloy (bistoury handle), the surface is strongly depleted in zinc, due to the well-known dezincification phenomenon. cuprite, malachite and sometimes chlorides (mostly atacamite or clinoatacamite) with the common dark-green colour. In the case of the Roman objects, the background (and the red inlays of the inkpot) is covered with the common burial corrosion products of copper-based alloys, i.e.

Concerning the non-patinated areas, the question of corrosion is irrelevant for the Egyptian objects, because the background is patinated and the inlays are made mostly of gold or silver alloys. On the other hand, malachite (see Figs 13.3 and 13.4) is obviously a corrosion product, mentioned as such in Table 13.4. Inkpot: Venus's and Adonis's himation + Eros wingĪs mentioned previously concerning the elemental analyses, the presence of nantokite and clinoatacamite, well known corrosion products observed on antique bronzes buried in soil, in the patinas of the Harpocrate body and statuette robe cannot be attributed to these corrosion products remaining because chlorine (as well as sulphur) is detected in the whole thickness of the patinas by RBS. 13.4).Ĭuprite + clinoatacamite (traces) + Au, AgĬuprite + chlorides (mostly clinoatacamite) + sulphides These results were confirmed by Raman micro-spectrometry, which showed also that the black patina of the Venus's himation of the inkpot contains noticeable amounts of malachite (copper carbonate, Cu 2CO3(OH) 2) ( Fig. The patina of the Harpocrate body is not cuprite, and is constituted mainly of chlorides (nantokite, CuCl, and clinoatacamite). The statuette patina also contains chloride (clinoatacamite, Cu 2Cl(OH) 3) and sulphides. The X-ray diffraction done on all objects (except the too small Harpocrate lock of hair background) show that nearly all the patinas are constituted of cuprite, Cu 2O (see the example in Fig. But this cannot be true for the Harpocrate body and the statuette patinas which contain high amounts of chlorine iron in the double aegis patina may also not be a burial residue. The additional elements Fe, Cl and S might be residues from the burial not eliminated by the restoration. One of the black patinas (the statuette robe) contains neither of these elements, and one contains silver but no gold (the bistoury).

Nearly all of them contain gold and from that point of view could be assimilated to ‘black copper’ or ‘black bronze’, but the gold and silver contents are very different, from 0.8 to 16% for gold, from 0 to 9% for silver. THE FOLLOWING COLORS ARE ALSO AVAILABLE IN 5-GALLON PAILS: Snow White, Lamp Black and Antique White.ĥ0-60 sq.ft./pint, 100-120 sq.ft./quart, 400-480 sq.ft.A Under 3 MeV protons b Under 6 MeV alpha particlesĮven if one takes into account the fact that the substrate alloys are very different from one object to another, it is clear that the compositions of the patinas are also very diverse. THE FOLLOWING COLORS ARE ALSO AVAILABLE IN GALLONS: Antique White, Basil, Coastal Blue, Dark Chocolate, Driftwood, Lamp Black, Linen, Millstone, Queenstown Gray, Seagull Gray, Snow White, Tuscan Red.

Patina green