The invention is a nonintrusive method of monitoring the cure of a polymeric material using an electromagnetic field to sense a change of resistance of the polymeric material in the electromagnetic field that occurs during curing. This change of resistance is used to vary the impedance of an alternating voltage power supply that produces the electromagnetic field and which change of impedance is measured periodically or continuously to monitor the cure of said polymeric material.PPApparatus for practicing the method of this invention may include a nonintrusive sensing head 11 providing an inner, electromagnetic core 12 within an open ended outer pot 14 formed of magnet material, the open end 17 of the pot core 14 being positioned from a selected area of the surface of a sheet 27 of the polymeric material. An alternating voltage supply circuit that includes an inductance coil 18 around said electromagnetic core 12 and a capacitor 23 connected in parallel with said inductance coil 18 to form a resonant tank circuit when energized. The resulting change in resistance of the polymeric material opposite said open end 17, a function of the curing thereof, is measured as a corresponding change in the impedance of said power supply circuit to thereby monitor the cure of the polymeric material in the selected area.
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