Preliminary study for detection of adhesive on a painted ceramic plate and varnish on printed paper using near-infrared hyperspectral imaging at wavelengths of 1.0–2.35 µm

Abstract We preliminarily examined whether it is possible to visualize synthetic materials applied to the surface of a base material by using near-infrared hyperspectral imaging at wavelengths of 1.0–2.35 µm. We focused on the applicability of this method for visualizing adhesives and varnishes, assessing the effect of underlying colorants on measurements, and selecting the optimal method for data analysis. Experimental samples were adhesive on a painted ceramic plate and varnish on printed paper. We performed correlation analysis, partial least squares regression analysis, linear discriminant analysis, decision tree, KNN and principal component scores 1 and 2 to evaluate the measurement data. The conventional method (visible/near-infrared spectroscopic/fluorescence photographs at wavelengths of 400–1000 nm.) could not visualize the adhesive on the painted ceramic plate or the varnish on the printed paper, whereas the new method could do so. Therefore, this method has the potential to be useful for inspecting the distribution of synthetic materials on the surface of a base material.