Badania próbek kamienia przy użyciu metody termowizyjnej

A research method known as thermovision finds a broad application in many fields o f science and technology. Its main advantage is the possibility to make a quick, remote and non-touching measurement o f parameters and to present results in form o f thermogram. The object o f this work was to check the usefulness o f the method in conservation works and in the first place, to evaluate the condition of historic stone objects. A thermovisual camera might become an instrument for a quick preliminary evaluation o f the condition o f large structures such as walls, elevations, or vaultings without a need to put up scaffolding and without, which is very important, sample-taking. The first stage was to carry out investigations on specially prepared samples. They were prepared in such a way that each o f them represented a model o f one phenomenon chosen out o f a number o f the factors occurring and overlapping with regard to objects in situ. This made easier the interpretation o f thermograms obtained. The samples had the form of plates from 20 cm to 42 cm in length, 20 cm wide and 4—5 cm thick. The material was limestone from „Pińczów” beds and sandstone from „Nietulisko” beds. The studies were carried out by means o f a Swedish thermovisual camera (Aga 680). The camera was studied to see its possibility to examine moistness, the presence o f salt in stone, homogenity o f the saturation with a reinforcing agent and to find out the coming-off o f the plaster and painting layers under whites. A number o f normal black and white, colour isothermic, profile and relief thermograms were received. In all cases one could notice differences in the temperature field between examined and standard samples (dry, non-salty, non-reinforced). Apart from the examination of moistness, where there is a natural difference o f temperatures between dry and wet stone, it was necessary to force the flow of heat by either heating samples in a dryer or by cooling their surfaces through rapid evaporation o f extraction naphtha. Salty and superficially reinforced samples proved warmer than standard samples, which is because of a change in the tightness o f stone. Samples taken to examine the coming-off of the plaster were observed during the cooling. Disjointed fragments cool down much quicker than places well adhering to the stone mass, which can be seen on recorded pictures. Moreover, the thermovisual method made it possible to single out white-covered colour painting layers. Colour zones are much more cooler than the white ones. The studies made and results obtained can be recognized as positive. It may be supposed that the thermovisual method shall become, next to other harmless methods, a new useful tool in the evaluation o f historic properties o f stone objects.