Other Asian innovations, such as paper and gunpowder, have a clear record of diffusion to Europe, with artifacts and records tracing their westward journey along trade and conquest routes. The print doesn’t have that kind of paper trail, says Valerie Hansen, a professor of Chinese history at Yale University. There is no evidence that European printers saw the fruits of Asian printing, such as money or pamphlets, and then tried to reverse-engineer the processes that made them, although it is plausible given the increasing contact between East and West in the thirteenth and fourteenth centuries.
A close look at both printing technologies has also revealed more differences than similarities: different inks (oil-based in Europe versus water-based in Asia) and different processes for creating the metal types, which stamp the ink on the page. In the 14th century, when Jikji was printed, Korean printers widely used a method called sandcasting to produce type, which involves filling lined molds with compressed sand. To create their movable type, Europeans traded sand for metal. One advantage was that, unlike sand, these metal molds could be reused, allowing individual typefaces to be mass-produced. This is one factor that is believed to have helped the printing press spread so quickly in Europe.
This innovation dates back to Gutenberg’s workshop a long time ago. But in the early 2000s, before a packed house at a New York City literary club, a pair of Princeton researchers floated a surprising theory: Maybe Gutenberg’s creations represented less than a singular technological triumph than people had previously thought.
His analysis focused on subtle imperfections in the text. If a metal mold had been used to create the types, each letter, for example, the entire letter a‘s on a page, it should be the same. But a mathematical analysis revealed that there were differences in the letters. The researchers hypothesized that the patterns were more in line with sand casting. Not everyone agrees with this interpretation, but since then there has been more evidence in its favor. As a way to begin a deeper study of Gutenberg’s methods for al Jikji project, Silverman asked Jonathan Thornton, a retired librarian and craftsman from the State University of New York at Buffalo, to see if he could recreate the typographical flaws using casting techniques in his own workshop. Lo and behold, it seemed to work.
The use of sand casting does not definitively link the two traditions—various forms of the technique were common in both Asia and Europe at the time—but it is another example of how the two traditions are a little closer to the what people think It would also mean that the metal mold, with its normal, replicable type, probably came later, and suggests that printing was a more gradual development than a sudden arrival on the scene. “It turns out we don’t know much about Gutenberg, this guy we’ve all been saying depends on modernity,” says Silverman.
Mining objects with X-rays are not a new method. A Gutenberg Bible had been analyzed in the 1980s in a much less powerful particle accelerator at the University of California, Davis. But the Stanford synchrotron is much more sensitive, expanding the range of elements and the level of detail it can see, says Mike Toth, an imaging expert who often works with ancient objects. These x-rays are often used to explore what cannot be seen, such as in cases where a document is rolled up and cannot be unfolded, or to check if another artist has covered up a hidden painting to save the canvas If a masking ink or pigment is known to be made of, say, iron and the ink covering it is not, the X-ray image can reveal this by isolating that element.