Feels like walking under broken glass

There are cracks in Prague's glass mosaics, and, if authorities don't act quickly, many will be lost forever, says conservation expert Tomáš Hájek.

Made of tiny colored-glass tiles, or tesserae, the mosaics depict biblical scenes or Czech mythology on many of Prague's most ornate buildings. Fragile and prone to developing an ugly gray crust, the mosaics are high-maintenance public art, and government agencies are not providing the funding to preserve them.

"It is a great shame because the mosaics are a unique art form with a long history in the Czech lands," says Hájek, former director general of the National Heritage Institute. "If we lose them, we lose part of our history."

The first glass mosaic north of the Alps was Czech, commissioned by Charles IV to decorate the South facade of St. Vitus' Cathedral. The mosaic depicts the Last Judgment; Christ, carried by a flock of curly-haired angels and flanked by the Virgin Mary and John the Baptist, raises the dead, while blue devils drag the damned to hell.

At the time the mosaic was created, Italy was pressuring Charles to move his court south and resurrect the Roman Empire. Constructed in exquisite detail in the Italian style, the mosaic sent a political message: Prague could rival Rome. In the Renaissance, glass mosaics fell out of fashion in favor of murals and sgraffito, but were resurrected during the Austro-Hungarian Empire, peaking in popularity at the turn of the 20th century. In the 1930s, a new type of mosaic-glass, potash, was invented in Czechoslovakia. Under communism, glass mosaics continued to thrive, and the number of potash colors swelled to 4,000, giving Czech mosaics extraordinary tonal subtlety.

After the Velvet Revolution, the Center of Art Handicrafts, where Czechoslovakia's mosaic experts were trained, closed its doors.

"The communist era was not a good time for people, but it was a good time for mosaics," Hájek says. "Since 1989, the knowledge of how to make and repair the mosaics has been lost, so we no longer have the experience or technology to preserve them."

In addition to suffering from the effects of acid rain and pollution, the mosaics are corrodible and degenerate over time. When the tiles come into contact with water, potassium in the glass gradually rises to the surface, where it combines with pollutants in the air to create a gray layer of corrosion on the tile's surface. Removing this crust without harming the glass is a time-consuming and expensive process, and simply removing the corrosion is a short-term strategy, because decay begins again immediately. Conservationists apply an additional protective coating.

"Our monuments create our collective memory," says Director of the Heritage Conservation Department Ivana Kyzourová. "A nation without memory is like a man without memory."

A few bright spots

While Hájek says Czech authorities fail to provide adequate funds to restore mosaics, there have recently been a few major success stories in mosaic conservation. With funding from the Getty Institute over eight years, the St. Vitus mosaic was repaired by an international team. In August, the National Technical Museum unveiled the restored Expo 58 glass mosaic fountain, created for the Czechoslovak pavilion at the Expo 58 world exhibition in Brussels, where it caused a sensation and won the main prize. Dana Hlobilová, a painter who worked on the fountain half a century ago, kept it in her back garden because she could not find anyone willing to repair it. While the fountain consisted of a corroded gray base when restoration began in 2007, it has now been restored to its former glory, with blue tiles and hand-blown glass bowls filled with cascading water.

The Last Judgment mosaic and Expo 58 Fountain are two of the foremost Czech glass mosaics. But, Hájek claims, hundreds of lesser-known works are neglected and decaying, and the extent of the problem remains unknown as there is no comprehensive list of glass mosaics.

"These artworks decorate the tops of dozens of buildings in Prague, yet very few people know about them; they walk by without seeing them," Hájek says. "I just want people to look up."

Natalia O'Hara can be reached at
features@praguepost.com