Page 173 - Copper and Bronze in Art: Corrosion, Colorants, Getty Museum Conservation, By David Scott

TABLE 5.2 VISUAL APPEARANCE AND XRD ANALYSIS OF CORROSION
PRODUCTS FORMED ON COPPER AFTER FOUR WEEKS OF EXPOSURE
TO VARIOUS ATMOSPHERES

ATMOSPHERE RH NaCI APPEARANCE CRYSTALLINE COMPOUNDS
^ g / c m ) (in order of strongest XRD reflections)
2
pure air 70% 21.5 Dull rosy/purple with Cuprite, Cu 2 0; halite, NaCI;
shiny dark spots tenorite, CuO
90% 33.5 Dull black /red /orange / Cuprite, Cu 2 0; nantokite,
purple with green spots CuCl; tenorite, CuO; malachite,
Cu 2 (OH) 2 C0 3 ; paratacamite,
Cu 2 (OH) 3 Cl
70% 26.0 Dull black / reddish brown Cuprite, Cu 2 0; paratacamite,
with shiny dark spots Cu 2 (OH) 3 Cl; tenorite, CuO;
botallackite, Cu 2 (OH) 3 Cl
90% 33.5 Dull black /red / orange Cuprite, Cu 2 0; tenorite, CuO;
paratacamite, Cu 2 (OH) 3 Cl
70% 20.5 Smooth opaque red/orange Cuprite, Cu 2 0; nantokite, CuCl
s o 2
90% 33.5 Dull reddish brown with Cuprite, Cu 2 0; brochantite,
green spots Cu 4 (OH) 6 S0 4 ; phase I; a
I
nantokite, CuCl
70% 40.0 Dull reddish brown Cuprite, Cu 2 0;
s o 2 + o 3
antlerite, Cu 3 (OH) 4 S0 4 ,
Cu 2<5 (OH) 3 S0 4 2H 2 0; phase II;
nantokite, CuCl
90% 23.0 Dull reddish brown with Cuprite, Cu 2 0; phase II; antlerite,
green spots Cu 3 (OH) 4 S0 4 ; brochantite,
Cu 4 (OH) 6 S0 4 ; nantokite, CuCl;
chalcantite, CuS0 4 -5H 2 0

After Strandberg and Johansson (1997b).
I
Phase I = new basic copper sulfate not fully characterized.
a