Handfeel standards
Abstract.
The article deals with the most important aspects of tissue softness. Unlike conventional properties, like tensile strength for instance, tissue softness, called Handfeel in the Industry, has no agreed-upon dimension. Therefore standard Handfeel samples can be assigned any arbitrary value. The best way to create such standards is described, along with a discussion of how to use them on paper machine for quality control. This activity is shown to contrast with periodic evaluation of Handfeel of a competitive array, requiring different techniques. The suitability of, or lack of, instruments to measure softness is also discussed.
Introduction.
Whenever people talk about tissue softness, I am always reminded of the saying of the great American writer, Mark Twain: "Everybody is always talking about the weather but no one does anything about it". The point of my analogy is that tissue softness, called Handfeel (HF) is a complicated subject, and HF is especially difficult to change. More specifically, consumers do not agree what constitutes softness, researchers do not quite know how to define it, and manufacturers do not know how to improve it on the
paper machine. My article will briefly touch upon the situation on the paper machine, but will spend most of the time discussing the most important issue: how to obtain standard HF samples. I will also point out the differences between testing production for quality control and comparing product HF to the products available in the market.Situation on the paper machine.
The most convenient way to talk about HF is with the aid of a HF- product tensile strength graph, strength expressed as geometric mean Breaking Length (BL). For a given brand Basis Weight (BW) and furnish composition is generally fixed and the relationship can be described by a hyperbola. For the purposes of this article, I am assuming that the relationship is simple negative, which is generally very close. Such a relationship is shown on Figure 1 for a given