Edward V. Sayre

NEUTRON ACTIVATION AUTORADIOGRAPHY OF OIL PAINTINGS

A very moderate, non-destructive radioactivation of oil paintings, induced by thermal neutron bombardment, such that approximately only one in 1012 of the atoms comprising any painting is transformed into a radioactive species, has been found to produce temporary radioactivity sufficient to expose photographic film placed in direct contact with the paintings. The resulting autoradiographs resemble conventional X-radiographs in that they reveal structural details in depth of both the painting and its support. Since the radioactivities arising from the different elements within a painting decay in different manners and at different rates, a series of significantly distinct auto radiographs can be obtained of any painting by making exposures through appropriate filters and at varying times following the original activation. Analysis of such a series of autoradiographs permits the identification of a number of the pigments used in a painting, together with information about the manner in which they were origi...

AUTHENTICATION OF PAINTINGS BY RALPH A. BLAKELOCK THROUGH NEUTRON ACTIVATION AUTORADIOGRAPHY.

Following his mental collapse at the end of the nineteenth century the paintings of Ralph A. Blakelock suddenly began to bring exceptionally high prices. Not surprisingly, therefore, many forgeries attributed to him were produced in the early twentieth century. In fact, some experts consider him to have been the most widely forged American painter. At Brookhaven National Laboratory a group of paintings attributed to him have been studied by thermal neutron activation autoradiography combined with solid state high resolution gamma-ray spectroscopy. Most of the paintings studied were of unquestioned authenticity coming from the collection of the Metropolitan Museum of Art, the National Collection of Fine Art of the Smithsonian Institution, the Sheldon Memorial Art Gallery of the University of Nebraska, and two private collectors with well established histories of acquisition. These included paintings produced by Blakelock both before and after his breakdown. In general a number of characteristic consistencies in the types of pigments and media used and how they were employed in these paintings were revealed by the activation study. Of course, major differences exist between his early and later work. However, a lack of these characteristics and hidden overpainted details which are not revealed in conventional X-ray radiographs have provided evidence that two of the paintings attributed to Ralph Blakelock are the work of other artists.Some paintings of Blakelocks contemporaries George Inness and Albert Ryder have also been investigated.

TECHNICAL EXAMINATION OF THE CLASSICAL BRONZE HORSE FROM THE METROPOLITAN MUSEUM OF ART

AbstractA thorough technical examination of the Metropolitan Museum of Art Bronze Horse (Ace. No. 23.69) has revealed that the technical evidence used to condemn it does not hold up under critical evaluation. The composition of the metal and core, the nature of the corrosion and its method of manufacture are consistent with the object being of ancient origin. Thermoluminescence experiments performed on the ceramic core material of the horse have proved that the bronze horse was manufactured in antiquity.

Direct Deposition of Barium Sulfate from Homogeneous Solution within Porous Stone

AbstractA porous, friable stone can be effectively consolidated and rendered resistant to the action of water, oxides of sulfur, oxides of carbon, and other atmospheric constituents by treating with an aqueous solution of a barium or strontium salt of a monoester of sulfuric acid, followed by hydrolysis. The treatment with the barium or strontium salt solutions effects impregnation of the stone in depth. Controlled hydrolysis from a homogeneous solution results in precipitation and deposition of well formed, granular barium or strontium sulfate throughout all those regions the salt solution has penetrated. This deposition of insoluble sulfate effects consolidation of the stone area, and inasmuch as the sulfate is highly insoluble and chemically inert, the stone is rendered resistant to attack.

Neutron activation Analysis of Oil Paintings by Ralph A. Blakelock

AbstractSix oil paintings purported to be the work of the much forged 19th century American artist, Ralph A. Blakelock, have been analyzed for stylistic and technical characteristics by the technique of neutron activation analysis. Two of the six paintings studied were found to have signatures other than Ralph Blakelocks which were over-painted. These two paintings were found to have stylistic differences from the other four and one of them used substantially different pigments than the others.The four Ralph Blakelock paintings were found to use a characteristic medium, thick application of the ground, similar pigments, and heavy layers of impasto build-up in certain areas of the paintings in which the major theme was being developed.The patient port of the Brookhaven Medical Reactor has been used for these irradiations and a painting as large as 28 inches by 36 inches has been uniformly activated by neutrons in a single irradiation. The dose absorbed by each of the paintings in these experiments was of ...