Bernard Keisch

“ We find that if the paint is old, compared to the 22-year half-life of the lead, let’s say 100 years old or more, then the amount of radioactivity from the lead-210 in the sample of paint will be equal to the amount of radioactivity from the radium in the sample. ”

“ Many artist’s materials, such as linseed oil, canvas, paper, and so on, come from plants or animals, and so will contain the same concentrations of carbon-14 as the atmosphere up to the time that the plant or animal dies. ”

“ But if you take a thimble full of liquid out of the bathtub, you can easily tell with neutron activation analysis that gold was added to the milk.
“Scientists call low concentrations of accidental impurities ‘trace elements’, and the amounts that are present are measured in parts per million rather than percent. One part per million is one ten-thousandth of a percent.” ”

“ One by one the samples were placed inside a shield consisting of a big pile of lead bricks. When the heavy door was opened, the boys could see a metal can inside the shield, which housed a detector (called a lithium-drifted germanium detector) that measured the gamma rays emitted by the sample. As each sample was placed near the detector the chemist turned on a gamma-ray spectrometer to which the detector was connected.
A tiny sample of lead white is sealed in a quartz vial which is bombarded with neutrons in a reactor.
Many of the atoms become radioactive, emitting gamma rays. ”

“ Using the methods that were then available, the experts showed that Van Meegeren had done a remarkable job of forgery and they were convinced that he had been telling the truth about painting those pictures.
“At the time, the important ways the experts used to examine a painting included studying the work with X rays, which could show another painting underneath, analyzing the pigments (or coloring materials) used in the paint, and examining the painting for certain signs of old age. ”

“ Previously he was a nuclear research chemist with the Phillips Petroleum Company and senior scientist at the Nuclear Science and Engineering Corporation. He has contributed articles on art authentication to a number of journals. For the AEC, in addition to this booklet, he has written The Atomic Fingerprint: Neutron Activation Analysis, Secrets of the Past: Nuclear Energy Applications in Art and Archaeology, and Lost Worlds: Nuclear Science and Archaeology.
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Nuclear energy is playing a vital role in the life of every man, woman, and child in the United States today. ”

“ Scientists at Carnegie-Mellon University have shown that this method will work. It is only a matter of making the measurements on the small samples available from presumably valuable paintings.”
The changing concentrations of carbon-14 in our atmosphere. High levels of carbon-14 in linseed oil and other painting materials will indicate that a work of art is only a few years old.
Carbon-14 radioactivity Older materials contain less as the carbon-14 decays away. In this period, decrease is due to the burning of large quantities of coal and oil as industry grew. ”

“ These are usually supposed to be paintings that are less than 100 years old. Present-day forgers like to forge paintings that aren’t very old because it’s easier to get away with. Now this new method, which will detect such recent forgeries, is based upon the presence of carbon-14, a radioactive isotope of carbon, in our atmosphere and in all things that grow on our planet.
“Ordinarily, carbon-14 is produced only by cosmic rays, and its concentrations in the atmosphere and in growing things would remain at a constant level. ”

“ The pulse-height analyzer is a device that sorts electrical impulses from the detector according to the energy of the gamma rays causing the impulses. The screen displays the gamma-ray spectrum and the electric typewriter automatically types out the data collected when the measurement is complete. ”

“ These involve methods that have been developed by scientists for other purposes, but are now being explored for use in authenticating works of art.
“For example, in Los Angeles, the county museum purchased an instrument known as a Spark Source Mass Spectrometer. Like activation analysis, this instrument will also measure small traces of impurities, but they have just set that up and it will take them years to explore the use of it for the type of problem we have been discussing. ”

“ These samples were taken from paintings of all ages, from some over 300 years old right up to others only a couple of years old. The old samples always showed equal amounts of radioactivity from lead-210 and radium while the modern ones always showed larger amounts of radioactivity from lead-210 than from radium. That meant that scientists had a way of definitely telling if a lead white paint was modern or not. ”

“ The lead-210 will then decay with its 22-year half-life.”
The radioactive series that starts with uranium is like a series of lakes connected by waterfalls. As long as uranium, the big one on top, has water in it, the others will be full and the falls will keep flowing. ”

“ It is, but we’re talking about such small quantities that its difficult for scientists using the most sensitive equipment to detect it. The uranium in the rock decays to another radioactive element and that one decays to another, and another, and another, and so 12 forth, in a series of elements that results in lead, which is not radioactive. In this series are two radioactive elements, radium and a radioactive isotope of lead, that help us to date paintings. ”

“ They believed that the reason the silver concentration was lower in the more modern material was because during the 19th century, lead refiners were doing a better job of removing all the valuable silver from lead.
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Silver concentrations in lead white. The concentrations generally decreased after the middle 1800s. Notice also how the concentrations were very similar for all the older paintings (before 1700) which were Dutch or Flemish. ”

“ And don’t forget the other unidentified paintings may also be genuine. We’ve proved that one is a fake, the experts believe that three of the others are copies, and then there are the two that might be Sisleys and are only waiting for a method to prove it. And we have one more that science managed to prove was really old. ”

“ But this letter says that the 43 Dutch government wants us to come to Holland as their guests as a reward for finding those paintings.”
These two paintings “The Lacemaker” and “The Smiling Girl” were thought to have been by Vermeer. A series of tests, including some of those described in this booklet, showed that the paintings are fairly old. However, some of the materials used are not typical of Vermeer, and the pictures are now thought to have been painted by a follower of the artist. ”