Passive and active infrared thermography: An overview of applications for the inspection of mosaic structures.

Infrared Thermography is a non destructive testing and evaluation (NDT&E) technique, which has been widely used for the investigation of cultural heritage and art objects. The main purpose of this study is to present the capabilities of both passive and active thermography for the inspection of mosaic structures, evaluating the performance of each testing approach through its application in representative mosaic structures. In situ passive thermography was applied on mosaic pavements in an attempt to acquire knowledge about their preservation state, while the active approach was used in order to study plastered mosaics and characterise the tesserae layer beneath the plaster. The results from this study revealed that passive approach can be efficiently applied as a moisture detection tool and a rapid monitoring technique of the mosaic condition, while the active thermographic investigation showed much more potentiality as quantitative information for the detected feature was further retrieved.