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- Computed tomography (1)
- Computertomographie (1)
- Conservation of wooden artwork (1)
- Holzschutz (1)
- Kulturgut aus Holz (1)
- Neutron radiology (1)
The objects of this investigation were sculptures taken from a ca. three hundred years old baroque epitaph of a church in Tonning, a town in Northern Germany. Around 1900 it was found in a disastrous state heavily damaged by wood-worm. At that time, the whole artwork was treated with the tar extract carbolineum as a remedy. Nowadays, this substance has been identified as carcinogenic, and its presence can be perceived by its stench and visually at certain spots on the surface where it has penetrated the covering paint.
A gold-painted sculpture of a massive wooden skull was interrogated with X-rays and fast neutrons to investigate the internal distribution of the carbolineum. The X-ray tomography, with its excellent spatial resolution revealed galleries left over from the worm infestation in the outer areas and cracks in the central region. The golden color coating appeared as a thick and dense layer. In comparison the tomography with fast neutrons, though being of lower resolution and yet unresolved artefacts revealed sections of slightly different densities in the bulk of the wood. These differences we attribute to the differences in the distribution of the impregnant in the wood, visible due to its higher hydrogen content making it less transparent for neutrons.
The baroque epitaph Reyer (1704) at the St. Laurentius church in Tönning was treated with carbolineum as a wood preservation agent in 1903. The subsequent constant migration of carbolineum through the layers of paint to the surface has had a detrimental effect on the aesthetic appearance of the epitaph. Carbolineum is an oily, water-insoluble, flammable, dark brown mixture of coal tar oil components. Due to its content of polycyclic aromatic hydrocarbons (PAH), which are classified as carcinogenic and harmful to the environment, the use of carbolineum has been forbidden. The aim of the project is to develop an exemplary Conservation treatment (hat will reduce the toxic contents of the historical wooden object. The new method should be applicable to similar objects that are also contaminated with carbolineum. The historic carbolineum was identified by the GC-MS method and the X-Ray computed tomography revealed the biological wood damage and previous restoration measures. Several decontamination methods such as the extraction with supercritical C02, with dichloromethane vapour/fluids, with 1,3-dioxolane or with petrol ether by vaccum impregnation were investigated. This project is founded by the Deutsche Bundesstiftung Umwelt (DBU).