Thousands of flood-damaged books saved thanks to special technology

Dried book, photo: Pavla Horakova

When a flood wave hit the Czech capital Prague two years ago it damaged not only buildings in the vicinity of the Vltava but also their contents. Entire archives were destroyed by water, including many precious historic prints. But luckily not all was lost to water, thanks to modern technology and quick decision-making. Tomas Rehak is the general director of the Municipal Library whose buildings and archives - including the department of rare prints - were heavily struck back in 2002.

Prague Municipal Library,  photo: Pavla Horakova
"Nearly all the prints from the department were deeply frozen. We still estimate - because not everything has been unfrozen - that at that time we lost less than 10 percent of the rare prints. More than 90 percent were deeply frozen in the freeze workshop and since then we started restoration work on them. So far, unfrozen and dried up are some 70 percent. What's left are 65 crates of books but most of them are the most valuable and the oldest ones."

As Tomas Rehak told me two technologies were used to dry up the soaked books.

"One is vacuum packing which is a very good technology, very preserving the old books and rare prints. However, it's a very very slow and time-consuming process and you need a lot of manpower. And the second technology we used for the majority of the books was drying at a normal temperature in the chambers normally used to dry up wood."

Although seemingly, both technologies work on a very common-sense principle, the head of the Municipal Library in Prague, Tomas Rehak, explains that they require a lot of expertise.

"In one case you just wrap the book in some dry material and press it in a vacuum packer. The vacuum packer is a machine normally used for vacuum packing of sausages and things like that. It's quite normal, you can use the result of the technology in every supermarket. The other one is just exposing the books to the air and letting the air circulate through the books. But in both cases what is most important is that you need very precise parameters of the technology: what should be the humidity of the air, what should be the temperature of the air, what speed should be the circulation, how many books you can put together in one chamber and so on. That needs quite a lot of experience. And of course, part of the experience came from abroad from cases like this throughout the world. And, of course, a lot of tests were made in the Czech Republic as well, by the specialists of the National Archive, the National Library and ourselves as well."

Two years later, vacuum drying and restoration are still going on. Some of the most valuable books have already been restored, probably the best known being the Prague Bible dating back to the 15th century. In September the Municipal Library is opening a new workshop where restoration work will continue for another three to five years.