Prague, Oct 8 (CTK) – A Czech firm has developed and tested an efficient method using hot air to kill the European house borer (Hylotrupes bajulus) that is damaging wooden structures of historical sights en masse, daily Pravo writes Thursday.
The small, some two-centimetre long, European house borer, known also as house longhorn beetle, Italian beetle or old-house borer, is a “nightmare” of heritage protectors, and this is why they have welcomed the method to get rid of this vermin – “to bake it like in a hot-air oven.”
The borer’s larvae are able to destroy roof frames of churches and chateaus quickly, and in a quite unnoticed manner, and they do not hesitate to eat up even wooden altars and Gothic statues, Pravo says.
The Thermosanace firm, seated in Ostrava, north Moravia, has verified the method in the unique complex of baroque buildings in Vraclav, east Bohemia. Last Friday, its employees were forcing hot air in the main nave of St Nicholas Church, and on Monday in its two towers.
“The principle is quite simple. The house borer’s body consists of proteins that decompose in a very high temperature. The “thermosanation” method is based on this,” Jan Svoboda, from the firm, told Pravo.
He explains that after wood is heated to a certain limit temperature, they can tell the investor that “everything in the wood is dead.”
Thought the house borer invaded the roof frames of the church built in 1724-30 by Carlo Antonio Canevalli only recently, it managed to cause enormous damage.
The machines heat the air to be forced in the church to 150-170 degrees Centigrade, while the temperature in the pipes’ outfall is about 120 degrees. Since hot air is mixed with the air in the church, the temperature drops to some 80 degrees. It must reach at least 100 to be efficient, which lasts some 12-14 hours, Svoboda said.
There is no danger of fire in the buildings since the minimum temperature for wood to catch fire is 180 degrees Centigrade, while in the case of spruce or fir wood it is some 230 degrees, he added.
Thermosanace is the first and only firm in the Czech Republic to offer this method of killing the house borer in the Czech Republic. The Vraclav complex has been its biggest contract so far, Pravo says.
It writes that this method based on hot air has been known for some 90 years. However, it started to be applied in a larger extent in Nordic countries, France and Germany at the end of the 20th century only. Now some 14 firms provide these services there.
Asked about the price, Svoboda only said “it is always cheaper if a historical roof frame is saved in time.” Though a new one might be even less expensive, the genuine historical value of the old one, which is actually priceless, would be lost then, he added.
