Technical Basics of Tissue Softness Measurement
Tissue softness measurement – the technical basics you need to know
Tissue softness is an essential physical property to consider when testing tissue samples. The softness of tissue has a huge impact on how comfortable it is when used against skin and how durable it is. Alongside optical properties such as brightness and color, softness is a key metric for assessing tissue.
Why test tissue softness?
There is a belief that it is hard to test tissue softness because it can be thought of a subjective perception, but ranking softness is less subjective than it used to be. Tissue can be tested for softness while bearing in mind the ways that the human brain perceives both surface and bulk softness. How soft a tissue feels to a consumer can have a big impact on whether they decide to purchase it or not.
Testing tissue softness with the Emtec
For an objective measurement of tissue softness, we recommend the Emtec TSA Tissue Softness Analyzer.
The output of the Emtec TSA goes far beyond just giving a single softness number with excellent correlation to hand feel panel tests. It provides all the data needed to explain the softness number, so it is easy to determine why one product is softer than another.
The feeling of softness one gets from a sample is a combination of three main parameters: structure, softness, and stiffness.
The Emtec TSA Tissue Softness Analyzer objectively measures the micro-surface variations (feeling of softness), the macro-surface variations (feeling of roughness) and the in-plane stiffness of any kind of tissue paper (base material and finished products). Here’s an explanation of some of the outputs it generates:
TS750 – Structure (smoothness/roughness) Parameter
The TS750 structure peak is the peak at a frequency that falls around 200 – 1,000 Hz. However, this frequency is not fixed like the TS7; it can vary in this range. This peak represents the structure of the sample which includes such things as creping and embossing. Generally, samples with lower structure strength will produce a lower TS750 peak. The creping and embossing process is carried out to realize a specific structure as it relates to hand feel. Creping and embossing will tend to make this peak higher.
TS7 – Softness Parameter
The TS7 softness peak is the frequency peak that occurs around 6.5 kHz on the noise spectrum graph. This peak represents the pure softness and is influenced by the fiber furnish, the degree of refining, the chemicals and other factors concerning the real softness of the sample. Generally, softer samples produce a lower TS7 peak.
D (mm/N) – Stiffness (deformation) Parameter
This is the deformation of the sample under a defined load and refers to its stiffness.
HF – Hand Feel
This HF number is the calculated figure which corresponds and correlates with the Hand Panel Test. The higher this number is the softer the test sample is and the better it is with respect to hand feel. Hand Feel is when someone touches the sample by hand and ranks it. This is a combination of the other parameters described above: TS750, TS7 and D.
Testing tissue softness with Industrial Physics
Thanks to our testing solutions, we have everything you need to test the softness, color, brightness and opacity of your tissue sample. For more information about how our engineers can help you select and test up new testing solutions, please do get in touch. To see our great range of paper, tissue and pulp testing machines, browse our Technidyne range.