Analysis of paint pigments

Transcription

1 Analysis of paint pigments Medieval oil paintings contained specific pigments to achieve the deep impressive color effects. A list of typical inorganic pigments and their chemical composition is :

2 Pigments available until 1800 AD Paint is composed of a colored pigment and a binder substance Pigment: colored powdered substance grinded from minerals salts, or dyes Binder: Material that evenly disperses the pigment, adheres to surface when paint applied and then dries. Paints are throughout uniform homogeneous mixtures. Lead white Lapis Lazuli Azurite Malachite Red lead Natural ultramarine Natural azurite Natural malachite Lead tin yellow Blue glass for smalt Natural azurite Synthetic malachite Azurite: copper carbonate Malachite: copper mineral Lead tin yellow Smalt Synthetic azurite

3 Pigment Charts

4 Discovery & Analysis of Medieval Scriptures

5 Breviarium van den Bergh Breviarium Van den Bergh has been illuminated 1510 by three different artists: Simon Bening, Gerard Horenbout, Jan Provoost. Comparison of color content lead to identification of the artist responsible for each illumination. Comparison of dark green and light green R. Klockenkämper, A. Von Bohlen, L. Moens, X-Ray Spectrometry 29 (2000) 119

6 St. Michael Birth of the Virgin St. Michael Birth of the Virgin Birth of Child Different ways to paint green Analysis of bright green in Breviarium Miniature Analysis of dark green in Breviarium Miniature St. Michael Birth of the Virgin St. Michael Birth of the Virgin Birth of Child mass fraction 3 mass fraction Ca Fe Cu Zn element Sn Au Pb 5 0 K Ca Fe Zn As Au Pb element 0 sample sample Jan Provoost painted light green with a mixture of blue (azurite), white lead, and yellow, all other samples contained green copper pigments. For dark green sample again close similarity between both samples except Pb. Sample from different miniature contained large Ca component and less As.

7 The content of ink FeSO 4 + gallotannic acid Ink preparation was an extremely important and difficult chemical technique. Ink had to maintain color and stability with time. 15th century manuscript by Raphael de Mercatellis ( ) Ferro-gallus ink prepared with an addition of Zinc and iron. The recipe allows the dating of the manuscript.

8 Raphael de Mercatellis The relative high Fe, Zn content is characteristic for Mercatellis and allows for a unique identification of his manuscripts. In addition the analysis shows that vermilion, HgS, is not part of the red ink composition; the Pb content suggests red lead or Minium.

9 The K-transition in iron-gallus ink The observed x-ray spectrum lines correspond to the energy of K-transitions. Calculate the difference between both of the characteristic X-ray transitions for iron and zinc and compare it with the previous spectrum. Data for Fe; Z = 26 K-edge: kev L-edges: , , kev K 1,K 1 : kev 2 Ex ( Z 1) 136. [ ev ] 1 for Fe: Z = Ex ( 25) 136. [ ev ] [[kev] 2 ] 2 for Zn: Z = Ex ( 29) 136. [ ev ] [[kev] 2 ] 2 Data for Zn; Z = 30 K-edge at: kev L-edges at: , , kev K 1,K 1 : kev 1 2 2

10 Sequencing scriptures: Goethe s Faust W. A. Mozart, The Magic Flute Faust I corrections Faust II Faust I J.W. v. Goethe, Faust I & Faust II Max Planck Institute fur Extraterrestial Physik, MPE Annual Report 2002

11 The Brittleness of old Documents

12 Elmyr de Hory

13 F for Fake by Orson Welles

14 Modigliani: Fake or Forgery? The art market is flooded with fake paintings of 20 th century artists such as... Matisse, Modigliani, Picasso... Co Pb Si Ar Pb Sn Cr Fe Co Cu Zn Pb Pb X-ray spectrum indicated the use of cerulean blue CoO n SnO 2 a pigment Modigliani did not use in any other of his paintings forgery?

15 Matisse Forgery Elmyr de Hory s forged Matisse, Odalisque,

16 Advanced Techniques in XRF Laser guidance poly-capillary optics spatial resolution 100 m lateral resolution

17 Summary X-Ray Fluorescence X-ray fluorescence has a wide range of application in art and archaeology. It is superior to radiography since it allows to determine the chemical constituency of archaeological artifacts or art samples in a nondestructive manner. This method provides opportunities of analysis beyond the absorption method of X-ray radiography. The method is based on X-ray induced emission of characteristic X-ray radiation from the sample material. Typically only medium or heavy mass elements can be detected by measuring either the characteristic energies of the K-transitions for low Z Elements - or L-transitions - for large Z elements - with Si(Li) detectors or crystal diffraction gratings.