In this study we analyze texture and profile features of painted strokes in order to identify the drawing media used for sketching underdrawings. Underdrawings are preliminary drawings on the panel prepared for paintings and are unseen in the finished work. Cameras working in the near infrared range allow the visualization of underdrawings. Due to the tiny width of the strokes we perform an alignment of the feature extraction windows in order to obtain a major content of the stroke texture. The method is tested on strokes applied on test panels and underdrawing strokes in IR images of medieval paintings.