New Insights into the Cleaning of Paintings

242 • smithsonian contributions to museum conservation
alkyd paint (continued)
disadvantages of, 90, 92
influence of pigments on, 62–63, 62, 63
properties of, 90, 90–91, 91
solvent mixtures and, 99–105, 100, 101,
102, 103, 104
ammonium citrate, use on unvarnished
paintings, 9
barrier paper, 186, 189, 190, 191, 192, 192,
194
binary solvent mixtures
behavior of, 97–105, 100
leaching resulting from, 100, 102–5, 102,
103, 104
swelling responses to, 99–100, 100, 101
borax, 13, 201–2
carbonated distilled water, 144
cavitation energy, 98, 98
chelating agents, 14, 21, 126, 140–44, 181
chromium oxide green, water sensitivity of,
109, 110, 110, 111, 111, 112
cleaning
of acrylic paintings (see acrylic paints)
of alkyd paintings, 94 (see also alkyd paint)
definition of, 11, 45
dry (see dry cleaning)
laser, 206, 209, 237–38
leaching resulting from (see leaching)
of modern paintings (see acrylic paints;
polyvinyl acetate (PVAc) paints)
of oil paintings (see oil paint)
oxalate films and, 85–87
of plywood panel paintings, 175–77
simple, 13
of unvarnished paintings (see unvarnished
paintings)
visual changes resulting from, 12
water-based (see water-based cleaning)
of water-stained areas, 205–7
commercial soap, 185–86. See also Vulpex
condition report, 10
conductivity, effect on water solubility of,
115–17, 117
copaiba balsam, 8
cosolvation, 98
in alkyd paint systems, 99, 105
dammar, 77
binding medium effect on removal of,
81–82
canvas support and removal of, 82, 234
color change on removal of, 80–81, 81
effects of varnishing with, 78, 80, 80
ground components and removal of, 82
size layer effect on removability of, 82
solubility of, 78
deionized water, oil paint sensitivity to, 109,
116, 117
dry cleaning
of oil paintings, 210, 213–14, 214, 216,
217
of unvarnished paintings (see dry cleaning,
unvarnished paintings)
dry cleaning, unvarnished paintings, 209–18
abrasion caused by, 214, 215, 216
products for, 210–11
residues left from, 215–16, 217, 218, 229–31
Schlürfer vacuum use for, 221
egg tempera, 39
chemistry of, 39–40
effect of dry swabs on, 42, 42, 43
effect of solvents on, 40–44
effect of water on, 40–43, 42, 43
emulsions, 126
effects on acrylic paints, 131, 132–33, 132,
133
enzymes, hydrolytic, 181–82
cleaning with, 182, 182–83
ethanol
effect on egg tempera, 40, 41, 42, 42, 43
effect on polymeric films, 166
foam cleaning, 225–27
gels, 21, 126, 179–80
effects on acrylic paints, 131, 132–33, 132,
133
polyvinyl acetate (PVAc), 201–3
rigid (see rigid gels)
tissue, 197–99
Golden Polymer Varnish, 170, 172, 172
gouache paint, 175
dry cleaning of, 210, 212, 212, 213–14,
215, 217, 218
grounds, color change in nineteenth-century,
77–84
heat, effect on oil paint, 56–57, 57
hexane, effect on oil paint, 56, 57, 57
ionic liquids, 233–35
ion migration, effects of, 64–65, 65
isooctane
effect on egg tempera, 41, 41–43, 42, 43
effect on polymeric films, 166
Italy
current cleaning methods in, 20–21
late twentieth century cleaning methods in,
17–21
water-based cleaning in, 20–21
laser cleaning, 206, 209, 237–38
leaching, 45, 69
of aged oil paint, 47, 48
of alkyd paint, 102–4, 102, 103
of new oil paint, 45–46
lead compounds
and alkyd paint durability, 62–63, 63
and oil paint durability, 57, 57, 60–61, 60,
61, 63–65, 64, 65
linseed oil paint, effect of solvents on, 52
margin test, 13
metal ions
and drying time of oil paint, 53, 54, 54–55,
59–60
and oil paint stability, 55, 56, 64–65, 65
metal soaps, 43, 47, 122, 123
Mineral Spirit Acrylic Gloss Varnish (MSA),
169–70, 171
Modular Cleaning Program (MCP), 140–41,
143–44, 145
National Gallery, London, cleaning controversy,
8, 9
oil paint
aging process of, 46–47
autoxidation of, 52–54, 59–60
chemistry of, 51–56
dry cleaning of, 210, 213–14, 214, 216, 217
hydrolysis of, 54
pigments and (see pigments)
reducing drying time of, 53, 54, 54–55
solvent effect on (see solvents)
solvent mixtures effect on, 99–100, 100,
101
stability of, 55–56, 56
water sensitivity of, 107–14
oil paintings
cleaning of (see oil paint)
unvarnished (see unvarnished paintings)
water-sensitive, 107, 109, 115–17
See also oil paint
optical coherence tomography (OCT), 27–29
advantage of, 27
disadvantage of, 27
overpaint removal, OCT use in, 27–29, 28
oxalate surface layers, 85–87
formation of, 86
paintings
aging of (see patina)
cleaning of (see cleaning)
nineteenth century cleaning of, 2–3, 8
oil (see oil paintings)
pre-nineteenth century cleaning of, 1–2
reasons for cleaning, 9, 239–40
twentieth century cleaning of, 3–4
unvarnished (see unvarnished paintings)
patina
nineteenth century view of, 2–3
pre-nineteenth century view of, 1–2
preservation of, 2
twentieth century view of, 3–4
paper
dry cleaning of, 14
wet cleaning of, 14
pH
effect on cleaning acrylic paintings,
141–42, 153
risks posed by high, 186
pigments
and durability of alkyd paint, 62–63, 63
and durability of oil paint, 57, 57, 60, 61,
62, 60–62, 63–64, 64
and water sensitivity of acrylic paint, 127,
127, 128, 128
and water sensitivity of oil paint, 108–14
and water sensitivity of polyvinyl acetate
(PVAc) paint, 127, 127, 128, 128
plywood panels, paintings on, 175–77