I. INTRODUCTION

This short and informal note addresses the topic of how to differentiate between "Consumer Properties" (i.e. product properties the consumer experiences while using the product), and "Diagnostic Properties" (i.e. properties we use to compare manufacturing technologies).

II. DISCUSSION

A: Consumer Properties

By this designation we generally mean those properties which the consumer experiences directly, like tensile strength, Bulk, Basis Weight (BW), Total Water Absorptive Capacity (TWA, g/unit area), Handfeel (HF). The first question that arises immediately when contemplating these entities: Are these the real properties the consumer experiences? Are they merely our most reproducible standard tests, which stand for the more-difficult-to-handle consumer properties? Or do we use these tests merely as quality control tools, reasoning that the quality of two products is the same if a sufficient number of their standard properties are the same. This last line of reason is similar to saying that, if the pressure and temperature of two ideal gases are the same, their volumes will also be the same.

This drastic stand has some important consequences. For instance its logic requires that on the basis of these tests alone, (i. e. without consumer validation) we do not change product specifications.

I am not as clear about the second option. Some of our tests stand for some in-use characteristics of our products, some not. The problem is finding out which stands for which. Even I think that tensile test gives an indication of the destructibility of our products; certainly wet strength does this for towels and facial tissues. Certainly HF is a pretty good predictor of softness, as experienced by the consumer. However the verdict is not so easy for other properties. Does the consumer observe BW? Or is it Bulk? Probably the latter. Is it Bulk per sheet or Bulk per wad? I don't know.

My heart is in the third category. Plain and simple, we use our standard tests to assure us of our quality: daily, monthly, and yearly. And, and this is a very important "and", to compare ourselves to our competitors.

B: Diagnostic Properties.

In addition to the properties described above, most of them have a "normalized", or unit counterparts. These normalized properties comprise Bulk/BW, Breaking Length (BL), Unit Water Absorptive Capacity (UWA, cc/g), and maybe others. There is considerable confusion as to which properties best indicate what the consumer is experiencing, and which to use for diagnostics.

In my opinion the consumer is getting "over-all" properties, not normalized ones. The consumer experiences Bulk, not Bulk/BW; TWA not UWA; strength (tensile strength for the lack of better) not BL. This means that if we wish to understand how our products compare to competitive products, we should always use non-normalized properties. If, on the other hand, our intention is to deduce from these tests some indication of the effectiveness of the technologies which produced the products, then, and only then, we should use normalized properties.

For me this distinction is of great importance. Failure to exercise extreme caution can lead to distorted competitive assessment. In my opinion, for comparison of products per se, we can simply tabulate the tests and look at them in that form. That is how the consumer does it, so to speak. He or she doesn't say, "Well, the Bulk of this product is low but for its low BW it is pretty high, hence I should look at Bulk/BW". Nor does she say something like: "This product is not very soft, but if the manufacturer had chosen to convert its Bulk/BW to HF by calendering, it could have come up with a much softer product". To repeat, consumers experience pure, over-all, non-normalized properties. Therefore if we wish to understand the performance of our products, we should use these types of tests.

If, on the other hand, we are interested in comparing technologies, or even paper machines, we should resort to normalized properties and plots. Clearly, in order to compare HF (or Bulk or TWA) of products, for instance, they must be at equal strength. If this can not be done, plotting HF values against some measure of strength, will accomplish the same thing; the product whose HF-strength line lies above that of its competitor is superior to one whose HF is below the line. But notice how easy it is to fall into careless usage! It is not the product which is superior but the technology which was used to produce it! The HF of the product, obviously, does not change just because we chose to plot it. A similar scenario exists when we confound total and unit Water Absorption (TWA and UWA respectively).

C: Illustrative example

Let us look at towel products made by two competitors, "A", and "B". Let us assume that the properties are as follows:

The consumer will experience product "A" (the product from manufacturer "A") as absorbing more water. Hence, if, for the sake of simplicity, TWA is the only (or most important) property driving consumer preference, we can expect product "A" to have a higher market share.

Which manufacturer has better equipment? Since this question requires the knowledge of fiber composition which complicates the issue, let's assume that they use identical furnish. Still, let us look at the normalized properties, using the units shown above:

The plot thickens. There would be a temptation to say that the UWA of product "A" is still higher, hence the manufacturing capability, or technology, of "A" is higher. But that would be wrong, since product "A" is 1/3^rd weaker. Technology comparisons should be done at equal strength, since manufacturer "B" always has the option to lower strength and increase UWA and TWA.

The correct way to carry out the comparison is to plot UWA against GMT/BW. Ideally, one should have several points, which would be the case if one tested several products. Still, I am showing such a curve with the two products. The curve is an approximate one, based on my experience.

As can be seen, curve "B", indicating technology capability for manufacturer "B" is well above that of "A". In fact, the difference is a little over 1 g/g at equal unit strength (GMT/BW). The above example is only for illustrative purposes; it is, of course, unlikely that a manufacturer with such technological superiority would field a product with inferior TWA.

In reality, products are seldom made from identical furnish. Hence, a comparison of technological capability requires that furnish composition too be taken into consideration. In essence, the properties need to be "fiber-normalized". There are several methods that can accomplish this, but they are beyond the scope of this paper.

III. CONCLUSIONS

It is important to differentiate between consumer and diagnostic properties. Consumer properties are the best indicators of product performance. Diagnostic, or normalized, properties should be used to compare technologies.