discrimination between coating over-thicknesses and adhesion defects S. Marinetti1, D. Robba2, F. Cernuschi2, P. G. Bison1, E. Grinzato1 1 CNR–ITC, C.so Stati Uniti, 4 35127 Padova ITALY e-mail: sergio.marinetti@itc.cnr.it 2 CESI, via Rubattino 54, 20134 Milano ITALY e-mail: davide.robba@cesi.it Thermal Non Destructive Evaluation/Testing (TNDE/T) is becoming more and more used as a rapid and effective mean to control the adhesion state of the coatings used for a variety of structural engineering materials. When performing in-field tests on TBC coated gas turbine blades, the main problem encountered is the difficulty to correctly interpret the experimental data. Stains, roughed regions, eroded areas and optical property variations are common sources of false alarms. In addition to these disturbances, that are detectable also in the visible band, another problem is due to the coating thickness changes that are not regarded as anomalies. Actually, they are very challenging to recognize because they are not visible and their thermal signal could be similar to the one produced by an adhesion defect. In this paper, a procedure to reliably discriminate thickness changes and real defects is proposed. Preliminary results are presented and discussed.