Restorers use goat hair in Charles Bridge renovation

There is perhaps no more iconic a Prague landmark than the 14th century Charles Bridge. Legend has it that egg yolks were mixed into the mortar to strengthen its construction. While that theory has never been fully confirmed, experts are now using another unusual ingredient – goat hair – to renovate the bridge’s sandstone railing.

Photo: Czech Television

A group of stonemasons can be seen these days working on the railing of the medieval Charles Bridge in the centre of Prague. Using a chisel and a hammer, they carefully remove the old filling between the stone blocks to the depth of about two centimetres and subsequently fill the space with new material.

Martin Malyš, one of the workers, told Czech Radio why it is better to use hand tools despite the availability of modern technologies:

“Using hand tools is probably the most ethical way to approach the renovation of such a valuable historical monument. You can actually choose how strong your strike will be so it is much more sensitive to the material.”

Photo: Czech Television

In some places, however, workers cannot do without modern technical equipment. Just like any ancient structures, the medieval bridge is not completely stable and, from time to time, cracks appear between the stones due to temperature fluctuations. Mr Malyš says these need to be adjusted with a special drill:

“In certain places, the cement cracks and gaps appear inside. What we try to do is clean the gaps, cut them and leave an opening that is several millimetres wide, so that the bridge can ‘breathe’. If we added more cement, it would crack even further.”

To make the cement more durable, restorers have decided to use a tried and tested medieval procedure, enforcing the mixture with goat hair.

Photo: Barbora Němcová,  Radio Prague International

Barbora Lišková is the spokeswoman of Prague’s Technical Roadway Administration, which is in charge of the reconstruction.

“It was suggested by the National Heritage Institute and we have agreed on the procedure with the restorer, who is overseeing the works.

“It is a historical procedure that has been used in the past. The goat hair makes the mortar stronger, but not as strong as to damage the stone.”

Barbora Lišková | Photo: Eva Dvořáková,  Český rozhlas

The renovation of the railing is part of a regular maintenance of Charles Bridge. At the same time, experts are also preparing its complete restoration of the medieval structure, which was last carried out about ten years ago, says Mrs. Lišková:

“At the time, Charles Bridge was completely insulated, with a desk on the bottom preventing leaks into the structure, so it hasn’t been deteriorating that much. That’s why we have enough time to prepare the future renovation.”

When the renovation gets underway is not yet clear, but it will definitely include the Old Town Bridge Tower, one of the world’s most beautiful Gothic gateways, which is in bad state of disrepair.

Authors: Ruth Fraňková , Adam Bejšovec
run audio