Potential error in density profile measurements for wood composites.

The vertical density profile of wood-based composites is often measured using X-ray densitometry. During preliminary studies, in which the density profiles of wood composites with discrete layers of varying density were measured, it was observed that the absolute density values of the layers were incorrect when compared to gravimetric measurements of the individual layers. This is due the recommended calibration process of the X-ray densitometer, which uses the overall density of the composite to determine the X-ray attenuation factor. The severity of the error increases with the difference between minimum and maximum density in the profile. [ABSTRACT FROM AUTHOR]