1. A method of determining a film coating thickness on a substrate and/or amount of one or more compositional ingredients of said film coating comprising: collecting a reference spectrum over a spectrum of infrared wavelengths from a reference sample wherein said thickness and/or amount of one or more compositional ingredients is present at a predetermined level, said collecting performed with an FT-IR spectrometer; obtaining a plurality of infrared spectroscopy spot measurements by randomly irradiating a predetermined area of said film coating on said substrate with infrared energy over said spectrum of wavelengths at a plurality of separate spots each having a spot size of from 1 mm 2 to 10 mm 2 on said film coating, said irradiating performed with FT-IR spectrometer; detecting said infrared energy reflected from said film coating on said substrate over said spectrum of wavelengths; said irradiating and said detecting steps are performed by a hand-held portable FT-IR spectrometer; performing multivariate analysis on the spectrum of said reflected infrared energy, said multivariate analysis comprising relative changes in said spectrum with respect to said reference spectrum; comparing results of said multivariate analysis with a predetermined calibration of model infrared energy spectra comprising said spectrum of wavelengths collected from a plurality of model film coatings, said model infrared energy spectra calibrated with respect to model film coatings comprising known film coating thickness and/or amount of one or more compositional ingredients; and, determining said thickness and/or amount of one or more compositional ingredients of said film coating and mapping said film coating according to said film coating thickness and/or amount of one or more compositional ingredients based on said predetermined calibration.