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  1. Uncovering Art Forgery Using Analytical Chemistry Patricia Munter University of Pennsylvania MCEP 2008

  2. Art and Science Meet • Many museums house laboratories for materials analysis • Mainly for restoration and conservation • Sometimes materials analysis can authenticate a work • How can science support the preservation of our cultural history?

  3. FAKE Real or Fake “Yesterday this picture was worth millions of guilders, and experts and art lovers would come from all over the world and pay money to see it. Today, it is worth nothing, and nobody would cross the street to see it for free. But the picture has not changed. What has?"  Van Meegeren, 1947 trial for forgery FAKE Art dealer Otto Wacker put 33 fake Van Goghs on the market Sold for 39.9 million dollars ??? FAKE FAKE Hung in a museum for 50 years Metropolitan Museum paid 50 million dollars FAKE Forger was almost sentenced to life in prison Pretend Picasso

  4. How Can a Forgery be Revealed? • Artistic style • Provenance • Scientific Analysis

  5. Which is the real Jackson Pollock painting? New York Times

  6. “Pollock (1946–49) Tudor City (1940–1949) 32 Jackson experimental works (gift & purchase) Bad condition. 4 both sides. All drawing boards. Robi paints. MacDougal Alley, 1958.” 32 Paintings Were Found in This Wrapper

  7. Paintings and Provenance

  8. Ellen Landau Art scholar, Case Western University Expert on authentication of works by Pollock Thought Matter paintings were authentic Francis O’Connor Compiled Catalogue Raisone of Pollock’s works Said Matter paintings were fakes Expert Opinion

  9. Forensic Analysis • Jackson Pollock died in 1956 • Analysis of materials can inform • Pigments have a known history

  10. Pigments as Historic Artifacts • Choice of colorants has changed for artists throughout history based on availability • Cave paintings of Lascaux, France • Minerals used • Hematite or iron red oxide -Fe2O3 • Limonite or yellow ocher – FeO(OH)·nH2O • Charcoal or carbon - C • Manganese dioxide - MnO2 • http://www.donsmaps.com/cavepaintings.html Photo: M. Burkitt 'The Old Stone Age' (1955), after Breuil

  11. More Colored Minerals • Ancient Egyptians ground minerals • Red lead (Pb3O4) • Malachite (CuCO3) • Orpiment (As2S3) • Manufactured “Egyptian Blue” first synthetic pigment • (CaCuS4O10)

  12. Preparation of More Pigments Devised • Lead white - lead(II) carbonate • PbCO3 • Verdigris – copper(II) acetate • Cu(CH3COO)2 • Ultramarine blue (1828) • (Na8-10Al6Si6O24S2-4)

  13. Mauve – First Artificial Organic Dye • Synthesized in 1856 by the 18 year old William Perkins • He was trying to make quinine from coal tar • Mixed aniline, toluidine and methanol – started an industry http://ce.t.soka.ac.jp/chem/iwanami/intorduct/ch11synthesis.pdf

  14. Color Index • 12000 products with 1700 generic names • All products are given a color index unique identifier • 10 pigment codes – PB, PBk, PBr, PG, PM, PO, PR, PV, PW, PY • Constitution number – sequential number given as new pigments are added to the index

  15. Colored Compounds • Variety of structural characteristics will make a compound appear colored • Fundamental similarity – all capable of absorbing selected wavelengths of light • When light is absorbed, electrons go to higher energy levels • Energy of the transition determines wavelength that is subtracted • Color we see are wavelengths not absorbed

  16. Color absorbed Red ------------------------- Orange -------------------- Yellow --------------------- Lemon Yellow ----------- Green ---------------------- Blue-green ---------------- Blue ------------------------ Indigo ---------------------- Violet ----------------------- Color seen Blue-green Blue Indigo Violet Purple Red Orange Yellow Lemon Yellow Color Perceptionhttp://www.chem.purdue.edu/gchelp/cchem/color2.html

  17. Color of Inorganic Pigments • Ligand field effects (iron oxide reds and yellows) • Charge transfer (chromates and ultramarines) • Pure semi-conductors (cadmium yellows and oranges)

  18. Coordination Compounds • Metal atom or ion surrounded by ligands • Crystal field theory explains splitting of d orbitals due to influence of ligands • Excitation of electrons from one d level to another Chang, 2002

  19. Charge Transfer • An electron moves from one atom to another in a compound • In Prussian blue: • Fe(II) reduces Fe(III) and it is oxidized to Fe(III) • Fe(III)4[Fe(II)(CN)6]3·xH2O Simple cubic lattice of Prussian blue. Fe(II) yellow Fe(III) red C gray N blue Ware, 2008

  20. Semiconductor • Vermillion (HgS) and Cadmium yellow (CdS) • Forbidden energy level in between allowed levels - called a band gap • If an electron is promoted to the conduction band, all the energies above the conduction band are absorbed http://www.nanolytics.de/index.php?lg=en&main=field_of_business&sub=why_colloids

  21. Charge transfer absorbs a narrow wavelength If green is absorbed, colors on either side will be reflected Red and blue will be seen, therefore the color seen is purple Semiconductors absorb a band of color If green is absorbed, all colors with higher frequency than green will be absorbed (green and blue) Yellow and red reflected, therefore orange will be seen Absorbance - Charge Transfer Versus Semiconductor

  22. π electrons delocalized over length of the conjugation Particle on a line model can be used to calculate the transition energy from the ground state to the excited state Conjugated Double Bonds Methylene bluehttp://omlc.ogi.edu/spectra/mb/index.html

  23. Pigments and Paints • Technically- artists use paints • Paints consist of 4 parts which may interfere with each other in an analysis • Pigment(s) • Medium or binder for suspension • Diluent • Additives

  24. Methods of Analysis Complement One Another • Fourier Transform Infrared Spectroscopy (FTIR) • Raman Spectroscopy • Laser Desorption Time of Flight Mass Spectrometry • Pyrolysis Gas Chromatography/ Mass Spectrometry • Scanning Electron Microscope / Energy Dispersive X-Ray Analysis

  25. IR IR Spectroscopy uses the absorption of infrared light measured as a function of wavelength to identify molecular compounds Vibrations that make changes in dipole moment are observed Spectrum is like a fingerprint FTIR Two mirror system One stationary, one pulses in coordination with laser Light source is split into 2 beams which go to the 2 mirrors then are directed back to splitter When beams combine, it is an interferogram Interferogram is directed at the sample Some energy is absorbed, transmitted energy is read by detector Data from detector is modified using an algorithm known as a Fourier transform IR versus FTIR

  26. Dispersive IR • Monochromator • Diffraction grating or prism • Breaks light into individual frequencies • Slow scanning speed http://www.umaine.edu/misl/ft_spectrometer.html

  27. Raman Spectroscopy • Raman effect refers to small amount of light that scatters inelastically from a molecule, at a different wavelength than the incident light • This absorbed energy is an intrinsic property of the molecule, independent of the incident wavelength • Raman instruments use lasers, wavelength chosen to give best signal to noise ratio. • Advantage of Raman - New instruments allow one to do analysis without any destruction of the sample

  28. Mass Spectrometry • Fragments molecules into ions using one of a number of techniques • Fragments are separated on the basis of mass to charge ratio (m/z) by magnetic or electric field • Molecular weight of the compound and mass of major ions gives information that helps elucidate the structure

  29. LDI-TOF-MS Laser desorption volatilizes and fragments the molecule No sample preparation only very small sample needed Time of flight refers to the detection system that relies on the time it takes to reach the detector correlating with the molecular weight Py-GC-MS Used for large molecules Generally used for polymer analysis Volatilizes sample by rapid heating on platinum wire, then sample is introduced into from a GC Mass Spec Systems Used for Art Analysis

  30. SEM/EDX • Useful for analyzing a pigment with a limited number of elements • High energy electromagnetic radiation directed at sample • Beam dislodges electron from sample • Higher energy electron from sample replaces missing electron and photon is released • Energy of photon is measured to determine elemental source of emission http://www.geosci.ipfw.edu/sem/semedx.html

  31. Harvard University Art Museums • Three works thought to be by Jackson Pollock (1912-1956) and owned by Alex Matter were analyzed using a variety of techniques to determine age and composition of materials

  32. Raman and SEM/EDX http://www.artmuseums.harvard.edu/home/HUAMreport012907.pdf

  33. LDI-TOF Mass Spectrometry http:// www.artmuseums.harvard.edu/home/HUAMreport012907.pdf

  34. Fourier Transform IR http://www.artmuseums.harvard.edu/home/HUAMreport012907.pdf

  35. PR254 – Diketopyrrolo-Pyrrole (DPP) Pigment Herbst, 2004

  36. PR254 Mass Spectrometry Spectrum Sodiated and di-sodiated species Loss of CO Wyplosz

  37. Mass Spectrum of Paint from a Car Fender Panel Shows presence of both Quinacridone Red ( MW 312) and PR254 (MW 356) Stachura, et al., 2007

  38. FTIR Spectrum of PR254 in Car Paint of Suspected Vehicle and Damaged Bumper Suspected hit and run vehicle Damaged car bumper Reference sample of PR254 Buzzini, et al., 2006

  39. Raman Spectra Comparing Paint from a Damaged Bumper and a Suspected Vehicle Damaged Car Bumper λexc = 785 nm Suspected Hit and Run Vehicle PR254 was identified, due to its Raman bands. Buzzini, et al., 2006

  40. Pyrolysis GC Mass Spectrometry http://www.artmuseums.harvard.edu/home/HUAMreport012907.pdf

  41. Conclusions • Pigment analysis is useful for authentication of art works and new analytical techniques are improving the analyses • Databases of spectra are needed for pigment data • Even with objective scientific data, experts from the art world are not in agreement over the Matter paintings

  42. References • Adar, F. Raman Applications That Are Driving a Rapidly Expanding Market. Spectroscopy. 2008, 23, 24-29. • Brill, T.B., Why Objects Appear as They Do. J. Chem. Educ. 1980, 57, 259-263. • Buzzini, P., Massonnet, G., Sermier, F.M., The Micro Raman Analysis of Paint Evidence In Criminalistics: Case Studies. J. Raman. Spectrosc. 2006, 37, 922-931. • FT-IR vs. Dispersive Infrared: Theory of Infrared Spectroscopy Instrumentation. http://www.thermo.com/eThermo/CMA/PDFs/Product/productPDF_21615.pdf (accessed 7/5/08). • Gardner, C.W. Annual James L. Waters Symposium at Pittcon: Raman Spectroscopy. J. Chem. Educ. 2007, 84, 49. • Gettens, R.J.; Painting Materials: A Short Encyclopedia; Dover Publications Inc.: New York, 1966 • Hao, Z., Iqbal, A. Some Aspects of Organic Pigments, Chem. Soc. Rev. 1997, 26, 203-213 • Herbst, W.; Industrial Organic Pigments; Wiley-VCH:Weinheim, Germany, 2004. • Jones-Smith, K., Mathur, H., Revisitng Pollock’s Drip Paintings, Nature2006, 444, E9-E10. • Kennedy, R., Drip Wars: A Pollock, in the Eyes of Art and Science. The New York Times. http://www.nytimes.com/2007/02/04/weekinreview/04kennedy.html?_r=2&ei=5088&en=e789e7a&oref (accessed 7/9/08). • Kincade, K. Laser-based Instrumentation Sheds New Light on Old Art. Laser FocusWorld. 2008, 44, 85-89. • Orna, M.V. Chemistry and Artist’s Colors: Part I. Light and Color. J. Chem. Educ. 1980, 57, 256-258. • Orna, M.V. Chemistry and Artist’s Colors: Part III. Preparation and Properties of Artist’s Pigments. J. Chem. Educ. 1980, 57, 267-269. • Orna, M.V. Chemistry, Color, and Art. J. Chem. Educ.2001, 78, 1305-1311.Papson, K., Stachura, S., Boralsky, L., Allison, J. Identification of Colorants in Pigmented Pen Inks by Laser Desorption Mass Spectrometry. J. Forensic Sci. 2008, 53, 100-106. • Papson, K., Stachura, S., Boralsky, L., Allison, J. Identification of Colorants in Pigmented Pen Inks by Laser Desorption Mass Spectrometry. J. Forensic Sci.2008, 53, 100-106. • Schulte, F., Brzezinka, K., Lutzenberger, K., Stege, H., Panne, U. Raman Spectroscopy of Synthetic Organic Pigments Used in 20th Century Works of Art. J. Raman. Spectrosc. [Online] 2008, Published online in Wiley Interscience. (www.interscience.wiley.com). • Stachura, S., Desiderio, V.J., Allison, J. Identification of Organic Pigments in Automotive Coatings Using Laser Desorption Mass Spectrometry. J. Forensic Sci. 2007, 52, 595-603. • Technical Analysis of Three Paintings Attributed to Jackson Pollock. http://www.artmuseums.harvard.edu/home/HUAMreport012907.pdf (accessed 7/9/08). • Ware, M., Prussian Blue: Artist’s Pigments and Chemists’ Sponge. J. Chem. Educ.2008, 85, 612-620. • Wyplosz, N., A Laser Desorption Mass Spectrometric Investigation of Artist’s Organic Pigments. PhD Dissertation (in preparation). University of Amsterdam, Amsterdam. [Online] http://www.amolf.nl/publications/theses/wyplosz/chapter_7.pdf (accessed 7/6/08). • Zollinger, H.; Color Chemistry: Synthesis, Properties and Applications of Organic Dyes and Pigments, 2nd revised edition; VCH: New York, 1991.