Materials Analysis

Material analysis has been conducted by Dr. Nicholas Eastaugh, of the University of Oxford, in London. Dr. Eastaugh heads up the Pigmentum Project, an ongoing effort to create the world’s most complete library of research on materials, fingerprints, and DNA for the art world. Dr. Eastaugh has analyzed initial samples from the collection, and they have proven to be consistent with known materials available at the time of Pollock. But paint analysis as a field has emerged as a thorny issue for the art world, as people representing themselves as experts seem to have fallen into a disagreement about when and what materials were available to Pollock. Reputable experts have given statements such as, “I don’t think he used house paints,” and “He didn’t use acrylics,” when such information is clearly confirmed in eyewitness accounts of Pollock’s working methodologies. All this misinformation clouds the picture and makes analysis more difficult than it needs to be. In order to prove what materials Pollock actually used, it would be very helpful to sample known works. However, owners of authenticated works by Pollock are understandably unwilling to let their very valuable pieces be tested for comparisons to unauthenticated works. They have nothing to gain, and generally fear there is much to lose. This misconception is difficult to overcome. The great tragedy of this exclusionist policy is that newly discovered works by Pollock could add immeasurably to the understanding of the artist’s true genius, and add more significance and stature to the value of all his work. Paintings from the collection are being tested for chemical matching to paints verified to exist on the floor of Pollock‘s studio. The canvases have also been tested and fit the correct time frame for use by Pollock. It is worthy to note that other experts have conducted materials analysis on this collection. Not all the experts agree on all the materials, (could they ever all agree on anything?) So costly analysis continues with no guaranteed results offered at any date as yet. In a notable contribution to authentication science, Dr. Eastaugh has published a superb scientific paper noting “Termination Dates” as evidence for novel materials being available to Pollock, and other artists, before the time that they were actually patented, or made available to the wider public. Even more intriguing, that some painters created ‘cocktails’ of materials that were unique to each individual painter. Dr. Eastaugh has identified a special limestone extender that was unique to Pollock, which has been found in the studio, and that also appears on pieces from Pollock’s Paradigm. This seems likely to fall into the category of “beyond a reasonable doubt!”

A Letter from Dr. Nicholas Eastaugh Ph.D. Dr. Nicholas Eastaugh Ph.D.; Dip. Cons.; B.Sc. SCIENTIFIC EXAMINATION REPORT Subject: An Untitled Composition thought to be by Jackson Pollock Our ref.: 071400.B7.01 Date: 16th November 2007 Seven paint samples taken from an Untitled Composition thought to be by Jackson Pollock have been examined using a suite of standard analytical techniques considered suitable for the characterization of historical paint1. This report presents the preliminary results from this analysis, specifically focusing on whether there are any overtly anachronistic pigments present that would immediately preclude an attribution to Pollock. As a secondary function, some observations will be made about the similarity between the pigments found and those known to have been used by Pollock for his dripped and poured works. Additionally, some areas requiring further work will be highlighted, including approaches that might be useful for the group of paintings as a whole not performed thus far. These analyses have been conducted in the context of ongoing research into the materials and techniques of Jackson Pollock being carried out by the present author and close colleagues that now encompasses results from Pollock’s studio materials and a number of his paintings in public collections. Some of this material has already been published, while further publication is planned for the remaining data. However, the results to date were available for reference in this study. A variety of colors was represented by the samples, a number of the fragments including more than one; consequently there was scope for a wide range of pigments also to be present. Colors included brown, blue, red, green, black and yellow, while in one fragment there was also a small amount of a silvery metallic pigment. Pigments identified included a titanium dioxide white, calcite, phthalocyanine blue and green, a carbon-based black, an organic yellow (probably an azo compound) and two organic red compounds (not fully identified). None of these is overtly anachronistic for a work by Jackson Pollock. A specific issue in the recent case of the so-called ‘Matter’ Pollocks was the apparent presence in a number of them of red DPP pigments. DPP pigments (diketopyrrolo pyrrole compounds, hence ‘DPP’) may have been discovered in the 1970s, but are currently largely considered to have become commercially available in the 1980s. As a result of this, pigments of this group are important both as date markers and counter-indicators for works by Pollock. The organic red compounds present in B7 were checked against reference material of CI Pigment Red 254, a DPP pigment; these were not a match. The relationship of the pigments found in B7 to those favored by Pollock is more complex. In terms of direct comparability, there are seemingly both similarities and differences. For example, Pollock appears to have favored the use of a synthetic ultramarine-based blue, while in B7 the blue is based on a phthalocyanine compound. On the other hand, there are various other pigments which are apparently of a comparable type to those found during the analysis of the Pollock studio material and paintings, including an ‘extender’ pigment based on a crushed limestone. Further analysis would undoubtedly benefit this research, allowing us to both extend our knowledge of the pieces in the collection and address the attribution questions more thoroughly and reliably. In particular, the following are proposed:

  1. Extension of the analysis to more of the works.
  2. Completion of the outstanding analysis of B7 and extension to other works.
  3. Use of other techniques such as Raman spectroscopy to analyze the materials in depth and make comparison to established works easier and more complete.
  4. Use of techniques such as radiocarbon to look at dating other components of the works such as the supports.

Dr. Nicholas Eastaugh Ph.D.

Scientific Report from Dr. Nicholas Eastaugh Ph.D

Subject: Painting J2
Our ref.: AAR-MP-002/A.J2
Date: 2nd April 2010

Introduction: This report contains summary information on the analysis of Pollock’s Paradigm painting J2, a work measuring approximately 26 inches by 40 inches  (above right) executed on paper. It was previously examined and a series of eight paint fragments were removed. These paint samples were subsequently transferred directly into the hands of Dr. Nicholas Eastaugh (NE), who has maintained holding since. This report will focus on the results of the analysis of these paint fragments. Details of the analytical techniques applied to the paint (including the protocols employed) are presented in a separate document, these being relevant to the group of paintings as a whole. However, in brief, the techniques concerned from which the results discussed here arise were:

• Polarised light microscopy (‘PLM’); • Scanning electron microscopy-energy dispersive X-ray spectrometry (‘SEM-EDX’); • Raman microscopy (‘Raman’); • Fourier transform infrared spectroscopy (‘FTIR’).

All are standard approaches in the study of historical paint materials. In the main, these techniques reveal data relating to the pigments present. Additionally, however, some information on binding media can be derived from the FTIR data, such as the presence of nitrocellulose lacquers and alterations resulting from certain pigment-medium interactions, as well as providing a tentative initial view on the presence of oils and other synthetic compounds. Further analysis is pending using gas chromatography-mass spectrometry (‘GC-MS’) and pyrolysis-GC-MS (‘Py-GC-MS’) to fully resolve the nature of the binding media. Additionally, studies by FTIR imaging have not yet been conducted. Specific results from the various analyses are tabulated below (Appendix I) and representative spectra from EDX, Raman, and FTIR attached (Appendix II). The principal compounds identified will be discussed below and the immediate implications outlined. A more detailed discussion of each compound in the context of Pollock’s Paradigm as a whole will be presented in a separate overview document. For example, brief indications of relevant dates associated with pigments such as known patent dates will be given here, but the overview will discuss the specific patterns of historical use in greater detail. Similarly, where there are points of correlation with previously analyzed Jackson Pollock material of good standing such as the Pollock-Krasner Studio (‘PKS’) paint cans, this will be mentioned here but discussed in greater depth elsewhere.

Analytical results: The following pigment types were identified in the samples: Aluminium metal flake: The metallic silver paints on this painting were found to contain an aluminium metal flake type pigment. This was readily identifiable from the EDX analysis and the particle morphology by PLM. It was also found as part of a metallic blue paint, mixed with a phthalocyanine-type pigment. Aluminium powder has been used as a metallic flake pigment, produced by stamping sheet aluminium. According to Gettens and Stout (1966), althoughaluminium powder was probably available from the mid-nineteenth century, it was not until after the introduction of the Hall process for aluminium production in 1886 that these became readily available. Moreover, Edwards (1927) indicates that aluminium powder as a commercial paint was not widely used until after 1920. An aluminium flake pigment was found by the present author in one of the PKS paint cans, that labeled “Metaleaf/Aluminium Paint/Ready Mixed” from the Pittsburgh company. Calcite: The calcite was identified by the presence of calcium in the EDX data, occasional detection of characteristic peaks in the Raman spectra and the particle morphology by PLM. This pigment is present as small angular fragments consistent with a very fine to medium ground limestone or similar source. Calcite is of ancient and continued use. Calcite was found in the PKS paint cans, in one instance associated with the unusual mineral Edenite, which was detected there by X-ray diffraction and thus unlikely to show in the present analyses. Carbon-based black: Several samples were characterized from the PLM examination as primarily containing a carbon-based black. Such pigments do not generally yield diagnostic EDX spectra except in certain specific cases where higher atomic weight elements such as phosphorus and sulfur can provide confirmation of types such as bone cokes and coals. In the present case the sample is characterized by fine dense, black particles or agglomerates of moderately uniform size, indicating a controlled manufacturing process such as might be encountered with modern (that is, twentieth century) synthesis processes. CI Pigment Orange 5: Samples [2] and [12] were found to contain CI Pigment Orange 5 (‘PO5’), primarily on the basis of Raman microscopy. Although the spectrum was relatively weak and the sample exhibited strong fluorescence, sufficient peaks were identifiable to be confident regarding the determination. PO5 belongs to the class of so-called b-naphthol pigments, which are among the oldest synthetic dyes known, b-naphthol was discovered in 1869 and manufactured by 1889; the pigmentary form, sometimes also known as Dinitroaniline Orange, was introduced in 1907. CI Pigment Yellow 12: This pigment (‘PY12’), a diarylide azo compound, was identified in samples [2] and [12] in association with the PO5, mainly on the basis of the Raman spectrum; it appears on the basis of the PLM examination to be a distinct phase to the orange also found here and may come from the base yellow wash on the paper (it was more intimately associated with paper fibres present in the sample). While not a pigment found in the PKS paint cans, PY12 was none-the-less produced commercially significantly prior to Jackson Pollock’s later works. According to Herbst and Hunger, for example, the first of the diarylide pigments to enter the market was CI Pigment Yellow 13 in 1935, while PY12 ‘…was produced and offered in the USA a few years later’; it has maintained commercial significance since that time. Clay minerals: A number of samples show consistent levels of either magnesium, aluminium, and silicon, or aluminium and silicon alone, by EDX. Detailed morphological study by SEM of the alumino-silicate types further suggested the presence of some of the characteristic flat plate-like particles associated with kaolinite, while those bearing all three elements exhibited particle morphologies consistent with palygorskite (sometimes known as ‘attapulgite’ or ‘Fuller’s earth’). In modern pigmentary grades of kaolinite particle sizes are of perhaps only 0.5μm, which would be consistent with the particle morphologies observed by PLM (essentially, extremely small particles difficult to resolve fully by optical means); FTIR analysis provided a match to ‘aluminium silicate’, essentially confirming this identification. Kaolinite has a long history of use. With the palygorskite, the particle size appears somewhat larger, although these are probably aggregates. Palygorskite has a similarly lengthy history of use. However, the general group of clay minerals is very large, with significant variation of composition and morphology; hence it can be difficult to provide definitive identifications. Lead chromate: Detection of lead and chromium by EDX in yellow to red and green pigments typically indicates the presence of a lead chromate type pigment, with confirmation by techniques such as Raman and PLM, as was the case here in several samples. Lead chromate was found in the PKS paint cans. Phthalocyanine compounds: The presence of phthalocyanine compounds was noted primarily by Raman. However, this was further confirmed by PLM with transmission microspectrophotometry, this hybrid technique being sensitive to detecting these pigments and differentiating them in low, dispersed, amounts because of the high spatial resolutions possible. Raman analysis further demonstrated the presence of blue and green forms including a specific form of the blue compound, one that matched a reference specimen of CI Pigment Blue 15:3, a b-modification of copper phthalocyanine. Phthalocyanine compounds were first significantly studied as pigments in 1929, with various blue and green forms being developed in the first half of the 1930s. According to Moser, Dupont introduced the first b-type phthalocyanine in 1949. They have continued in general use since that time. Phthalocyanines were observed in the PKS paint cans. Titanium dioxide white: Detection of titanium by EDX, particle morphology by PLM and identification of Raman bands for rutile confirmed the presence of a rutile-type titanium dioxide pigment. However, although titanium was found in many of the samples, detection of associated Raman bands was not universal across the material. Titanium dioxide whites were first developed as commercial products in the earlier twentieth century and their technical superiority over other types of white hiding pigment were such that by the time of Jackson Pollock’s later activity they were coming to dominate this sector of the paint market. A rutile type titanium dioxide pigment was found for example in the PKS paint cans. Sample [12] also contained a distinct phase based on calcite and a red organic pigment. It has not been possible to identify the red pigment and another form of analysis (such as a chromatographic method) is probably required to fully understand its composition. Provisional identification of binding media was accomplished from examination of FTIR spectra of the samples, but is subject to review when analysis is complete by GC-MS and Py-GC-MS. However, this indicated that there are likely to be at least three categories of binding media present: drying oil(s), alkyd resin(s) and nitrocellulose. The last of these is usually confirmed by FTIR analysis specifically as it is not amenable to the GC-MS/Py-GC-MS protocols employed. No materials precluding an origin for J2 prior to Jackson Pollock’s death in 1956 have been found to this point of the material analysis.

Dr. Nicholas Eastaugh

Pollock’s Paradigm J2

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