Skip to main content

Currently Skimming:

Paint Media Analysis--Michael R. Schilling
Pages 186-205

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.


From page 186...
... Although many instrumental analysis techniques now exist for identifying organic substances, several key factors limit the actual number of techniques that are suitable for identifying organic binding media. To begin, typical samples removed from paintings weigh in the range of 1 to 50 micrograms; in many instances the medium simply may be present below instrumental detection limits.
From page 187...
... In research at the Getty Conservation Institute, quantitative GC-MS procedures were developed for identifying organic binding media based on proteins, oils, and plant gums. The procedures were validated on test paints that were subjected to two types of artificial aging (six weeks at 80°C and 500 hours in a Weather-OMeter light exposure chamber at 50 percent RH and 50°C)
From page 188...
... ; these amino acids were excluded from the final dataset. Samples tested for plant gum media were hydrolyzed in trifluoroacetic acid, and the monosaccharides were analyzed as O-methyloxime acetate derivatives (see Appendix B for details)
From page 189...
... Using the method of correlation coefficients, the quantitative stable amino acid composition for each sample was compared to those of the common binding media in order to find the closest match, as listed in Table 4 (Anderson, 1987) ; the same method was employed for identification of plant gums (see Table 3)
From page 190...
... Blue & paper 14.9 3.5 2.1 4.3 51.6 13.1 10.4 12 Playing Card (King) Red & fibers 14.2 2.7 1.6 3.2 55.8 12.3 10.2 18 Black & paper 17.1 5.5 3.6 6.9 52.6 10.8 3.5 11 Sedation Green & paper 14.0 13.1 9.0 16.8 25.6 21.0 0.5 5 Street to M'Bari Yellow & blue 18.7 3.7 2.0 3.5 52.4 12.6 7.2 14 Blue 17.8 3.1 1.7 3.2 51.2 13.2 9.7 13 Struggle Series #11 Brown 22.2 16.2 12.4 24.1 14.4 10.8 0.0 12 Students and Books Yellow 25.0 17.8 13.1 23.5 10.4 8.7 1.5 16 Brown & ground 23.1 18.3 13.2 22.4 15.4 6.7 0.9 6 Yellow 22.0 15.1 12.2 22.3 20.6 7.8 0.0 8 Vaudeville Blue 24.0 17.0 12.9 26.1 17.9 2.1 0.0 6 Ground 12.4 16.8 11.1 21.8 8.8 28.9 0.2 3
From page 191...
... Chemistry of Oil Paints The chemistry of oil paint is very complex, and even with modern analytical equipment, it is difficult to understand the precise details of the interactions between the polymerized oil media and pigments. Nonetheless, a substantial body of knowledge has been developed that sheds some light on the drying and subsequent aging of oil paints (van den Berg, 2002)
From page 192...
... . As oil paints dry, unsaturated fatty acids react with oxygen to form a polymerized oil matrix; triglycerides and diglycerides provide additional cross-links to the polymerized oil matrix via their glycerol backbones.
From page 193...
... Additional alteration of the fatty acid composition of oil paints occurs by evaporation of free fatty acids. So-called "ghost images" that develop on the glass next to framed and glazed oil paintings provide clear evidence of fatty acid evaporation (Williams, 1989)
From page 194...
... Correlation Coefficient Painting Paint Sample Collagen Egg Yolk Casein Other Blind Beggars Red 0.82 0.29 0.33 0.99 (1 part glue, 2 parts casein) Checker Players Paint & ground ­0.06 0.79 0.91 Daybreak Yellow 0.06 0.98 0.39 Library Ochre 0.13 0.90 0.19 0.99 (yolk & ultramarine, light aged)
From page 195...
... Guggenheim Museum, New York Untitled I, 1977, Adriana and Robert Mnuchin Untitled V, 1977, Albright-Knox Art Gallery, Buffalo, New York chromatogram using an HP-INNOWAX capillary column. This procedure derivatizes all three forms of fatty acids in oil paints (free fatty acids, pigment soaps, and glycerides)
From page 196...
... Void spaces inside paint samples indicate that de Kooning mixed water into them, and the test results show that this procedure had no deleterious effect on the extent of hydrolysis. Another finding was that the sticky paints tended to contain cadmium pigments or synthetic organic dyestuffs, whereas no clear relationship to the drying rate of the oil medium was apparent.
From page 197...
... TABLE 6 Test Results for Willem de Kooning Paint Samples % % Painting, Date Sample Description P/S P/G D/G Hydrolyzed Oil Oil(s) Door..., 1960 Pink, voids, matte 3.5 0.26 0.32 32 25 Poppy/linseed White, voids, matte, brittle 4.1 0.26 0.36 19 29 Poppy Spike's..., 1960 Yellow, soft, matte 0.9 0.04 0.66 40 52 Castor Blue, brittle, matte 3.7 0.24 0.34 12 23 Poppy/castor Pastorale, 1963 Light blue, voids, brittle 4.8 0.2 0.36 32 48 Poppy Rosy..., 1963 Bright yellow, soft 1.9 0.07 0.57 48 50 Castor/linseed Woman..., 1964 Pink, soft 3.4 0.1 0.23 29 18 Poppy/linseed Woman, 1965 Amber drip 2.6 0.14 0.65 17 52 Linseed/safflower Visit, 1966 Orange, soft 2.6 0.12 0.5 33 24 Linseed/safflower Wrinkled gray-green, soft 2.6 0.15 0.23 34 31 Linseed/safflower Two..., 1967 Orange, soft, soft 2.1 0.17 0.32 29 31 Linseed/safflower Pink, wrinkled, soft 2.7 0.16 0.3 32 33 Safflower Amber gel, wrinkled flesh 2.8 0.09 0.35 22 59 Safflower Amityville, 1971 Yellow, wrinkled, soft 3.9 0.21 0.28 28 23 Poppy/linseed White, soft 3.7 0.24 0.25 15 38 Poppy/linseed Whose..., 1975 Amber drip, sticky 2.6 0.09 0.28 25 29 Linseed/safflower Red, soft, sticky 2.7 0.14 0.26 26 67 Safflower Maroon, soft, stringy 3.8 0.13 0.34 26 24 Poppy/castor Untitled I, 1977 White, wrinkled 1.3 0.05 0.36 23 59 Linseed Pink-white, wrinkled 1.4 0.04 0.34 37 67 Linseed Untitled V, 1977 Gray, wrinkled, voids 1.8 0.07 0.31 17 40 Linseed Black, wrinkled 0.91 0.03 0.72 66 48 Castor Dark blue, wrinkled, soft 2.0 0.07 0.48 37 59 Linseed 197
From page 198...
... CONCLUSIONS Quantitative GC-MS is an important analytical technique for characterizing natural products that have been used by artists as organic binding media. In the study of modern paintings the technique provides valuable information that enhances our understanding of artists' materials and techniques, permits changes in material composition to be monitored, and contributes to the development of appropriate conservation strategies.
From page 199...
... 1997. Fatty acid and glycerol content of lipids; effects of ageing and solvent extraction on the composition of oil paints.
From page 200...
... APPENDIX A PROCEDURE FOR QUANTITATIVE GC-MS ANALYSIS OF AMINO ACIDS, FATTY ACIDS, AND GLYCEROL AS (TERT -BUTYL-DIMETHYLSILYL) DERIVATIVES All analytical standards were obtained from Aldrich Chemical Company.
From page 201...
... Using a quadratic curve fit forcing through the origin gives correlation coefficients of 0.995 or better for most analytes over the calibration range of 2 to 50 ppm. Stable amino acid compositions for various reference materials are listed in Table 8.
From page 202...
... Evaporate the contents to dryness using a nitrogen stream while warming the vial to 50°C. Rinse with 40 µl of absolute ethanol (Spectrum Chemical)
From page 203...
... 20.9 16.6 13.3 23.2 14.1 11.9 0.0 Yolk & ultramarine, light aged 23.5 15.7 13.1 22.3 15.8 9.5 0.0 Yolk, aged at 80°C 21.0 19.2 14.6 21.9 13.6 9.8 0.0 Rowney egg tempera with cadmium red 23.6 18.7 14.4 24.5 16.1 2.7 0.0 Yolk, light aged 23.5 16.0 13.4 22.7 15.5 8.9 0.0 Yolk & lead white, light aged 23.3 16.0 14.0 21.0 18.5 7.1 0.0 1 part glue, 2 parts casein 13.3 10.1 7.3 13.0 27.3 22.9 6.1 1 part glue, 3 parts casein 12.7 11.6 8.5 15.0 23.2 24.2 4.8 NOTE: All data taken from (M. Schilling, H
From page 204...
... , and inject into GC-MS. GC-MS Conditions for a 15 M × 0.25 mm × 0.25 µm DB-WAX Capillary Column: Helium carrier set to a linear velocity of 60 cm/sec; splitless injector at 240°C with a 60 sec purge off time; MS transfer line set to 240°C.
From page 205...
... 205 PAINT MEDIA ANALYSIS Calibration parameters: See Table 9 for the list of quantitation ions for the MOA derivatives. Using a linear curve fit forcing through the origin gives correlation coefficients of 0.995 or better for most analytes over the calibration range of 2 to 50 ppm.


This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More information on Chapter Skim is available.