WINTERTHUR, Del. - If Paul Revere had made all the silver cups and spoons attributed to him, he would not have had time for his famous midnight ride.

Curators at the Winterthur Museum here repeat this wry observation out of exasperation and a sense of triumph. Exasperation over the prevalence not only of faux Revere silver but of many other misidentified and faked art and antiques on the market and even in respected collections like their own. And triumph because, with high-tech investigative methods, they are increasingly able to expose artistic impostors.

Over recent years, art and science have intersected in the back rooms of museums, and in laboratories stocked with instruments designed mainly to probe living cells, examine mineral structures, inspect rocket parts and study moon rocks. As a result, the palette of art language, the talk of pigment and binder, chiaroscuro and pentimento, now includes terms from the science lexicon like X-ray fluorescence and infrared spectroscopy.

The role of scientific analysis in the art world is beginning to share a place in the public galleries. Several years ago, the Metropolitan Museum of Art in New York held an exhibition, "Rembrandt/Not Rembrandt," to show how X-ray and nuclear radiation technologies helped reveal the methods of the Dutch master, detect changes through restorations and separate real Rembrandts from the works of pupils and imitators.

At the Winterthur, a museum on the manicured grounds of a former du Pont estate that specializes in early American paintings and decorative art, curators have gone public with the fakes in their collection and examples of how they used science to find them out. "In the public mind, art and science are like oil and water - they don't mix," said Charles F. Hummel, a curator emeritus at Winterthur. "We find them a good mix, enabling us to authenticate and identify materials and also understand how to restore genuine pieces."

Forgeries exposed

Using space-age technologies, scientists at Winterthur have determined that in a collection of more than 1,000 silver pieces, ,, supposedly by early American silversmiths like Revere, 76 percent of them were not genuine; most were 20th-century copies meant to deceive collectors. They also exposed forgeries of letters by George Washington and portraits by Charles Willson Peale. That desk on which Thomas Jefferson was supposed to have written the Declaration of Independence, they discovered, was actually a replica that over the years came to be regarded as the real thing.

"Deliberate faking still goes on," Hummel said, "but it's not as big a problem as the passing off of good-quality reproductions as the genuine article." In the latter case the owners, not the makers of the piece, perpetrate the fraud.

Curators and scientists are still debating the provenance of a beautifully painted chest in the Pennsylvania German style. Their examination of drill holes, nails and paint chemistry reveals that the date painted on the lid - 1792 - is undoubtedly a deception. The remaining question is whether the Himmelbergerin chest was actually made in the late 19th century or early in this century.

Suspicion was cast on the chest, acquired by the du Pont family in the 1920s, when experts in antiques noted a few years ago that the style of the painted decoration appeared to be 19th century. So they submitted a tiny sample of the paint to chemical analysis by an instrument known as a Fourier transform infrared spectroscope. Bombarded with infrared light, invisible to the human eye, a sample reacts in a way that produces a computer-generated "fingerprint" of the different chemical compounds present in the object. These fingerprints are then compared with those of known compounds.

In this case, a green pigment was revealed to contain a large amount of copper stearate, a paint additive not introduced until the late 19th century. In further tests, peg holes in the chest were X-rayed with much the same energies used in a dentist's office, and this produced the most telling evidence, recalled Gregory Landrey, Winterthur's director of conservation. The holes had been made with a type of drill not available in 1792.

And then there were the nails. "From the outside," Landrey said, "the nails looked convincing, just like wrought nails, but they were not." The nails had been made from wire, a manufacturing technique not common until the 1870s, and then hammered to look like a wrought nail used in similar chests known to be authentic 18th-century furniture.

Is this a deliberate fake? Landrey pondered the question before answering, probably not.

"Other things suggest that it's not an intentional fake," he said. "On the backside, nuts are exposed on the outside. If the artisan was trying to deceive a collector, he wouldn't have put bolts in. Also, there are 18 nails holding the bottom of one drawer. That's out of character. There would have been wooden pegs."

A case in point

Janice H. Carlson, a senior scientist at Winterthur, presides over the laboratory in which many a fake has been unmasked. Around her are microscopes, computers and X-ray and infrared machines, a setting more familiar to universities and space science centers than museums. One of the most useful instruments, the energy dispersive X-ray fluorescence machine, was developed for the space researchers analyzing moon rocks without destroying or damaging the samples.

Standing by the machine, Carlson recalled her investigative triumph in the case of the Lenssen silver. "We devoted a ton of time collecting data and making sense of the data," she said. "It took five or six analyses of each object, and there were a thousand objects."

In the 1930s, Arthur Lenssen, a New York insurance executive, began collecting antiques, especially Colonial silver. He kept meticulous records of his purchases, noting that many of the silver pieces were represented as works of such notable early American silversmiths as Elias Pelletreau, Paul Revere and John Hull. This made them rare and expensive collectibles. Yet certain dealers always seem to come up with the valuable items Lenssen was looking for, which perhaps should have raised suspicions.

But not until the Lenssen collection, which had been donated to the Stevens Institute of Technology in Hoboken, N.J., was examined at Winterthur did the truth come out.

Using the X-ray fluorescence machine, Carlson irradiated the objects, one by one. An X-ray beam focused on the surface of an object causes it to emit radiations that are analyzed by a %J detector. The emissions are displayed on a computer screen in the shape of a graph with peaks and valleys. The graph thus reveals the chemical elements of material in the objects.

In one of the early tests, Carlson determined that a dram cup, purportedly made in 1650 by Hull, a Boston silversmith, consisted of extremely pure silver - 92.5 percent silver and 5.5 percent copper. There were no traces of gold or lead, commonly found in Colonial silver.

The results, Carlson knew, were "characteristic of modern silver, made after the mid-19th century when electrolytic refining processes made it possible to produce silver containing none of its natural impurities."

Training conservators

Only a half-dozen or so museums in the country have such well-equipped laboratories for the scientific analysis of art, and Winterthur is the only one that trains future museum conservators in such techniques. It does this through a degree-granting program operated with the University of Delaware.

At the Metropolitan Museum of Art in New York, paintings are examined in a two-story studio with hugh lightboards for the study of X-rays. The focus of research is the investigation of the working methods of the masters and the restoration of old canvases. But when one of the museum's acquisitions, "Man of Sorrows" purportedly by an unknown Flemish painter of the 15th century, was suspected of being a fake, the focus shifted to sleuthing.

The science of dendrochronology, tree-ring dating, established that the oak panel on which the paint was applied was from northern Europe in the late 15th century. Examination of the paint and details of the body of Christ by X-rays and under ultraviolet light showed that they were for the most part authentic.

The scientific study, said Hubert von Sonnenburg, the museum's chairman of painting conservation, established that the painting "is not an outright forgery, but a rather cunningly restored original, with surviving authentic components."

Other museums join in consortiums to take advantage of the new investigative technologies, as in the case of the New York and New England institutions that operate the Williamstown Art Conservation Center in Massachusetts. Sometimes the center's scientific analyses also expose a clever fraud.

Examining a portrait attributed to Francois Clouet, a 16th-century French painter, James Martin, the director of analytical sciences, found some Prussian blue, a synthetic pigment developed in the 18th century. Further testing showed that the portrait was probably painted after 1850.

And a collector who thought he had a baseball bat used by Shoeless Joe Jackson before World War I had reason to use the famous plea, "Say it ain't so," that a boy once voiced to the fallen ballplayer. Ingredients of the black paint and other clues examined at the Williamstown center suggested that the bat was made no earlier than 1929, a decade after Jackson was banned from baseball for his part in the Black Sox betting scandal of 1919.

Pub Date: 7/26/98