IPST now offers to its testing and research clients a quantitative, unambiguous measurement of tissue softness using a combination of ultrasonic and mechanical testing methods. Tissue softness has traditionally been subjectively assessed through "hand feel" by a panel of experts. Such ranking methods are arbitrary and remain proprietary. Capitalizing on the 1990's IPST legacy of the pioneering work of Chuck Habeger and reviewed in publications by John Waterhouse, the IPST Paper Physics lab, under the direction of Dr. Roman Popil, has acquired the commercialized version of the out-of-plane ultrasonic testing instrument manufactured by Sonysis in Atlanta. This instrument, the "OPUS", is custom-made to have a light transducer contact pressure of 20 kPa specific for the application to compressible tissue and non-woven substrates. By measuring the speed of sound through the sheet and the subsequent relative attenuation of the transmitted signal amplitude, a software algorithm calculates the relative softness number according to the reported and established Waterhouse formula. Ultrasonic measurements are non-destructive and are quickly made without the requirement for sample cutting or preparation.

To complement the ultrasonic measurement, a "Handle-o-Meter" produced by Thwing Albert Instrument Company has also been acquired. This instrument mimics the subjective "hand-feel" or "handle" test by precisely measuring the force required to push through a fabric or tissue through a machined slot. Together, the OPUS and the Handle-o-Meter provide an inter-corroborating quantitative reproducible and controlled measurement of what is otherwise a rather intangible subjective and important quality for paper industry. Dr. Popil reports that this new IPST testing capability allows precise comparisons between various products and processes that IPST testing clients should find to be interesting and of value towards their marketing and product development programs. For further information, contact roman.popil@ipst.gatech.edu (404) 894-9722.