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The battle of Murten: A haunted painting?

Analytische Strategien, 13.12.2011 Patrik Geissbühler, Natalie Fedotova, Caroline Münsterer. The battle of Murten: A haunted painting?. 1. Famous swiss painter (19 th century) His art: s ymbolism (anti realism and naturalism) He developed: parallelism . Ferdinand Hodler (1853 – 1918).

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The battle of Murten: A haunted painting?

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  1. Analytische Strategien, 13.12.2011 Patrik Geissbühler, Natalie Fedotova, Caroline Münsterer The battle of Murten: A haunted painting? 1

  2. Famous swiss painter (19thcentury) His art: symbolism (anti realism and naturalism) He developed: parallelism Ferdinand Hodler (1853 – 1918) self-portrait, 1916 (source: wikipedia) 3

  3. Paint = particles of pigment suspended in a drying oil organic binding media (e.g. linseed, walnut, poppy) Color Linseed Oil: oleic acid palmitic acid (source: Fiebig,DGF) 4

  4. Fast dryers = change the color of reflected or transmitted light as the result of wavelength-selective absorption Slow dryers Pigments: • Lead white • (70% of lead carbonate, • 30% lead hydrate) • made from metallic • lead and vinegar • Vine/bone black (amorphous carbon) • Produced through charring of bones/ desiccated grape vines Ochre naturally tinted clay (hydrated iron (III) oxide) Verdigris (copper carbonate, copper chloride) application of acetic acid to copper plates Source: wikipedia 5

  5. Curing of oil paintings • unsaturated fatty acids react with oxygen  hydroperoxides • hydroperoxides undergo cross-linking • polymerization (skin-like film) and decomposition (aging) • drying process is accelerated by certain metal salts (catalyst) (Porter et al., 1995; picture: wikipedia) 6

  6. Chemical analysis typical samples: 1 to 50 μg contamination representative sampling! analytical techniques: Non invasive: optical microscopy X-Ray imaging XRF Invasive non destructive: FTIR destructive: MS 7

  7. Our task: Assessment of: „The battle of Murten“ 8

  8. Question 1:For what (other) reasons are paintings framed with a glass layer? 9

  9. (moisture damage) • prevent UV-radiation damages • prevent damage from vandalism/ acccidental cause http://www.cwaller.de/fr_didaktik.htm 10

  10. Question 2: What is a ghost image? 11

  11. = hazy film that appears on the inside surface of the protective glass. impairs proper viewing of the painting! Formed through evaporation of substances from bloomings 12

  12. Questions 3&4:Study the object and describe what you see! Consider: • Do all areas of the ghost image look similar? • Do all paintings produce a ghost image? • Which ones produce a stronger /weaker one? Why? • Hypothesis: Define a hypothesis for the phenomena. Incude in the discussion of issues such as the origin of the deposited material of the composition of the paint where it originated from, the chemical alteration with paint age, the influence of the different paint component on the formation of the efflorescing compounds. 13

  13. Nomenclature of whitening blanching, blooming, efflorescence, chalking, clouding, sweating, flooding/flotation, crazing, fading, bleaching, hazing, whitening, crystallization, micro-fissures, micro-cracking, micro-voids, blushing, mould etc. Blanching Origin : Binding media Pigments Layer structure A physical break-up of the paint surface ( a surface phenomena) Efflorescense More specific for crystalline (inorganic) deposits on the water-soluble salts 14

  14. Not all areas of the ghost image look similar:  most intense over dark colours • Which paintings show ghost images? unvarnished • medium: linseed, walnut, poppy oil • pigments: • Madder lake, Vandyke brown, • Bone black, ochre stronger ghost image • Lead white and cobalt blue • less blooming • Chrome yellow weak ghost image Why ? Singer et al., 1995 15

  15. Possible explanations: • 1) Slow drying pigments  intense ghost formation, enriched in saturated fatty acids • ochre or vine black, or made from walnut or puppy oil media  slow • dryer in oil and moderate high to oil indices • lead white, cobalt blue and verdigris  catalyse the drying process and • reduce ghost image formation • 2) Also the difference in fatty acids deposits on the paints can be described with thermal diffusion processes: dark colours heat quicker and stronger 16

  16. Why do free fatty acids migrate to the surface? Free volume theory  understanding of migration processes in paint medium Water steam permeation Thermal diffusion Efflorescense Ghost images 17

  17. Different classes of compounds Triglycerides and metal soaps Free fatty acids Isomerized fatty acids Oleic acid with Stearic and palmitic acid  liquidable to migrate Dicarboxylic acids (azelaic acid) , saturated fatty acids and alizarin  similiraty profile between the free fattty acids and the triglyceroids Linoleic acids,ratio of palmic/stearic acid of 2:1 typical for linseed stand oil 18

  18. Question 5: Experimental Testing • What are we looking for ? → Triglycerides E.g: → Free Fatty Acids E.g: Palmitic Acid (C16H32O2) Stearic acid (C18H36O2) Oleic Acid (C18H34O2) 19

  19. Liberation of fatty acids from trigylcerides: → Metal Carboxylates (Metal Soaps) 20

  20. Analytic techniques • Method to distinguish between metal soaps and free fatty acids: → FTIR: • Information about location and concentration of different chemical species in a solid sample • Almost no sample preparation needed • Non destructive, but invasive 21

  21. Method to determine the detailed fatty acid composition: • → GC-MS: • Information about retention time & mass • Able to separate different free fatty acids fast & identify them using Mass Spectrometry • Sample size: few μL • Sample needs to be a liquid or a gas • → Derivatisation with (H3C)3SiCl 22

  22. Method that can do both: • → SIMS • Information about the location of different chemical species in a solid sample (SIMS imaging) • Also possible to get mass spectrum from the sample to identify free fatty acid composition • Little preparation necessary • Destructive 23

  23. Sample Taking • Mechanically → Scratch of paint from the image border → Get sample from each color/paint type → As much substance as possible from the glass surface → Seal samples in vials before transportation to the lab • Measurements to avoid contamination → Always wear gloves → Protective mask → Protective clothing → Collect samples in a clean room 24

  24. Sample Preparation All compounds can be identified by GC-MS after derivatisation with TMSCl in Pyridine 25

  25. Question 6: How can the reoccurrence of a ghost image be prevented? 26

  26. Possible regeneration methods: • mechanically (brush)  no real removal of the bloomings! • anionic tensides  needs aftercleaning • white spirit  best results • heat  back-diffusion of FFA, but: change in colour and brilliance Possible prevention methods: • varnishing (to fill pores)  changes in brilliance • coating with beeswax • no IR-radiation source  heat enhances fatty acid migration • minimal exposure to humidity (glass, diffusion barrier) Hons et al., 2005; Zumbühl et al., 2004 27

  27. Literature • Keune, K.; Binding medium, pigments and metal soaps characterised and localised in paint cross sections, 2005 • Hons Sandra, Johanna von Stockhausen, Stefan Zumbuehl „Migrationsprozesse freier Fettsäuren in Malmittelfilmen: Untersuchung zur Entfernung von Ausblühungen und Überlegungen zur präventiven Konservierung“ ZKK Zeitschrift für Kunsttechnologie und Konservierung: 19 (1) 2005, 32-37. • Koller J., Burmester A, “Blanching of unvarnished Modern Paintings. A Case Study on a Painting by Serge Poliakoff” Cleaning, Retouching and Coatings-Technology and Practice for Easel Paitings and Polychrome Sculpture” Preprintsof the Contributions to the Brussel Congress, London, (1990) 138-143. • Schilling, M.R. et al. “Gas chromatographic determination of the fatty acid and glycerol content of lipids. IV. Evaporation of fatty acids and the formation of ghost images by framed oil paintings” ICOM Committee for conservation triennial meeting. Triennial meeting (12th), Lyon, 29 August-3 September 1999: preprints. Vol. 1, James & James, London, 1999, 242-247. • Singer B., Devenport J, Wise D., “Examination of a Blooming Problem in a Collection of unvarnished and varnished oil paintings.” The Conservator 13 (1995) 3-9 • Van den Berg, J.D.J. et al. “Chemical changes in curing and ageing oil paintings” ICOM Committee for conservation triennial meeting. Triennial meeting (12th), Lyon, 29 August-3 September 1999: preprints. Vol. 1, James & James, London, 1999, 248-253. • Zumbühl, S. et al.“Migrations FreierFettsäure in Malmittelfimen – Induzierte Migration durchWasserdampfpermeation und thermodynamische Diffusion durchheterogeneDichtfluktuation” ZKK ZeitschriftfürKunsttechnologie und Konservierung, 18(1) 2004, 61-69. Pictures: Keune, K.; Binding medium, pigments and metal soaps characterised and localised in paint cross sections, 2005 28

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