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Table 1 Reading pastor (ca. 1885) by Ferdinand Hodler. Analytical results

From: Faded shine…. The degradation of brass powder in two nineteenth century paintings

Sample

FTIR diamond window

ATR–FTIR–FPA

GC–MS

LM

XRF

SEM–EDX

SRXTM

Overall interpretation

Metallic flakes

n/a

No signal

n/a

C01 and C02 yellow metal leaf fragment 1–4 μm thickness embedded in the varnish layer

Cu Zn

C01 Cu 84 Zn 16

Cl

C03 (same location as C2)

Flat thin high X-ray absorbing particles carrying from 1 to 4 μm thick and up to 80 μm long. Bent and folded

Coarsely ground brass metal leaf applied over the paint

Green agglomerates

2918, 2850, 1585, 1467, 1420 cm−1 copper carboxylates

2918, 2850, 1540 cm−1 zinc carboxylates

1718 cm−1 free fatty acids

C01 2926, 1741, 1583, 1543, 1518, 1457, 1417 cm−1 copper and zinc and carboxylates

C02 region one 2922, 2854, 1735 1585, 1540, 1525, 1455, 1418 copper, zinc and lead carboxylates in heterogeneous distribution

Methyl palmitate (P), methyl stearate(S) (P/S = 3), small amount of methyl oleate, methyl laureate, methyl myristate, dimethyl azelate and dimethyl suberate

C01 and C02 homogeneous dark green non-fluorescent mass. Wide range of thicknesses

Cu Zn

C01 Cu 83 Zn 17

C03 (same location as C2)

Large homogeneous low absorbing/scattering material. Shape closely related to the outline of the metal particles

Reaction between fatty acids with copper and zinc from the metallic pigment. Distribution of zinc and copper soaps is on locations heterogeneous. With higher zinc soap concentration on the upper areas of the soap agglomerates

Paint build-up

n/a

FTIR–FPA C01 Red layer:

2925, 2850, 1738, 1168 sh cm−1 Oil

1520 cm−1 lead carboxylate

3522, 1398, 1044 cm−1 basic lead white

1100 cm−1 aluminium phosphate

Pink layer: 2925, 2850, 1735, 1165 cm−1 Oil

1520 cm−1 lead carboxylate

3522, 1398, 1044 cm−1 basic lead white. 1151, 1078, 1019, 934 cm−1 starch

C02 Grey layer: 2925, 2850, 1735, 1165 cm−1 Oil

1520 cm−1 lead carboxylate

3522, 1398, 1044 cm−1 basic lead white

n/a

C01 Red layer:

red and white pigmented layer with few black particles

Pink layer:

White and red pigmented layer

C02 Grey layer:

Black, red and blue pigment particles sparingly distributed in a white pigmented layer

Same location as C01 Pb; Fe Sn

Same location as C02 Pb; Fe Sn Sb

C01 Red layer:

Pb containing white pigment particles

Al, P containing red particles

Pink layer:

Pb

Hg, S containing particles

C02 Grey layer: Pb

C03 (same location as C2)

Two layers. Top layer higher absorbing/scattering than the lower

Oil paint.

C01 Red layer: red pigment on aluminium phosphate substrate. Lead white. Lead soaps

Pink Layer: vermillion lead white

C02 Grey layer: lead white, unidentified black, blue and red pigment particles

Varnish

2954, 2870, 1712, 1457, 1385 cm−1 natural resin possibly dammar

2934, 2859 sh, 1733 sh, 1415, 1245, 1102 cm−1 oil component

C01 2930, 2854, 1715 1456, 1391 cm−1 natural resin. 2933 sh, 2850 sh, 1732 sh, 1418, 1165, 1106 cm−1 lipid contribution

C02 no clear signal

n/a

C01 Clear layer:

10 microns thick, embedding the metal particles and soap aggregates. Fluorescent under ultraviolet illumination

C02 Clear layer: approx. 12 μm thick. Fluorescent under ultraviolet illumination

n/a

n/a

C03 too low X-ray absorption at the energy used and not distinguishable from the resin used to fix the sample on the holder. n/a

Natural resin varnish. Presence of lipids