We measured moisture content of ceramic plaster using near infrared reflectance spectroscopy (NIRS) as required by the ceramic industry. The moisture content and the normalized spectral reflectance were measured and correlated at the wavelengths of the spectral absorptance peaks (αλ), spectral sensitivity peaks (Sλ) and normalized sensitivity peaks (Sλn), in the wavelength range of 900–2500 nm. The best model was obtained by the scanning method, normalizing the sensitivity and doing a minimization of the standard error of estimate (SE). The αλ-peaks, sλ-peaks and sλn-peaks were not found at the same wavelength, for the three studied wavebands. The optimal model in terms of SE was the linear model at 1420 nm (sλ-peak), for the ceramist drying range with a SE1420=1.25 (R2=0.96). The results indicate the feasibility of NIRS to non-contact moisture content measures of plaster in the studied range, even more for ceramist range.
Near infrared reflectance spectroscopy Ceramic plaster Moisture content Non-contact measurement