**4.2 Objective evaluation of fabric handle**

For a long time, handle has been estimated by the organoleptic method. The producers and users of textile products try to formulate in words the impression of touching the flat textile product. In general, fabric hand is primarily assessed subjectively in a few minutes. Although this is a fast and convenient sort of quality control, the subjective nature of fabric handle leads to serious variations in quality assessment (Sülar & Okur, 2008a) and does not analyze the core of the problem connected with the influence of factors creating the particular sensations. This was why in the 1930s investigations were commenced into an objective measurement of the features which are decisive for handle. The common goal in objective measurement systems was to eliminate the human element in hand assessment and develop quantitative factors that could be measured in a laboratory (Kocik et al., 2005).

Peirce was a forerunner of such investigations with his works connected with determining the bending rigidity and compressibility of flat textile products (Kocik et al., 2005; as cited in Pierce, 1930). At the turn of the 1960s, researchers from the Swedish Textile Institute (TEFO) (Kocik et al., 2005; as cited in Eeg-Olofsson, 1957; as cited in Eeg-Olofsson, 1959; as cited in Olofsson, 1965; as cited in Olofsson & Ogucki; 1966; as cited in Lindberg et al., 1961; as cited in Lindberg et al., 1960) carried out intensive investigations into this matter. These research works led to determining the dependencies between the features of flat textile products subjected to bending, buckling, shearing, and compressing, and the susceptibility of these products to manufacturing clothing. Lindberg (Kocik et al., 2005; as cited in Lindberg et al., 1960) was the first researcher who applied the theory of buckling for estimating the behaviour of fabrics in the clothing manufacturing process. Kawabata and Niwa were followers of Peirce and the Swedish researchers, who since 1968 have conducted research into handle. These investigations have been crowned by the design and construction of a measuring system which serves for objective estimation of handle (Kocik et al., 2005; as cited in Kawabata et al., 1973; as cited in Kawabata et al., 1996).

Objective assessment attempts to find the relationships between fabric hand and some physical or mechanical properties of a fabric objectively. It quantitatively describes fabric hand by using translation result from some measured values of relevant attributes of a fabric. Techniques used for objective hand evaluations are based on special instruments for measuring handle related properties (Bakar, 2004).

Several attempts have been made to measure fabric handle properties objectively described simply as "Fabric Objective Measurement (FOM)", and also a number of items of equipment have been introduced for this purpose (Hasani & Planck, 2009; Bishop, 1996).

#### **4.2.1 Objective measurement systems**

The KES-F system (Kawabata's Hand Evaluation System for Fabrics) was developed in Japan by the Hand Evaluation and Standardization Committee (HESC, established in 1972)

This subjective hand evaluation system requires years of experience and can obviously be influenced by the personal preferences of the assessor as mentioned before. A fabric may be felt light, soft, mellow, smooth, crisp, heavy, harsh, rough, furry, fuzzy or downy soft. So there is a need to replace the subjective assessment of fabrics by experts with an objective machine-based system which will give consistent and reproducible results (Hu, 2008).

For a long time, handle has been estimated by the organoleptic method. The producers and users of textile products try to formulate in words the impression of touching the flat textile product. In general, fabric hand is primarily assessed subjectively in a few minutes. Although this is a fast and convenient sort of quality control, the subjective nature of fabric handle leads to serious variations in quality assessment (Sülar & Okur, 2008a) and does not analyze the core of the problem connected with the influence of factors creating the particular sensations. This was why in the 1930s investigations were commenced into an objective measurement of the features which are decisive for handle. The common goal in objective measurement systems was to eliminate the human element in hand assessment and develop quantitative factors that could be measured in a laboratory (Kocik et al., 2005). Peirce was a forerunner of such investigations with his works connected with determining the bending rigidity and compressibility of flat textile products (Kocik et al., 2005; as cited in Pierce, 1930). At the turn of the 1960s, researchers from the Swedish Textile Institute (TEFO) (Kocik et al., 2005; as cited in Eeg-Olofsson, 1957; as cited in Eeg-Olofsson, 1959; as cited in Olofsson, 1965; as cited in Olofsson & Ogucki; 1966; as cited in Lindberg et al., 1961; as cited in Lindberg et al., 1960) carried out intensive investigations into this matter. These research works led to determining the dependencies between the features of flat textile products subjected to bending, buckling, shearing, and compressing, and the susceptibility of these products to manufacturing clothing. Lindberg (Kocik et al., 2005; as cited in Lindberg et al., 1960) was the first researcher who applied the theory of buckling for estimating the behaviour of fabrics in the clothing manufacturing process. Kawabata and Niwa were followers of Peirce and the Swedish researchers, who since 1968 have conducted research into handle. These investigations have been crowned by the design and construction of a measuring system which serves for objective estimation of handle (Kocik et al., 2005; as cited

Objective assessment attempts to find the relationships between fabric hand and some physical or mechanical properties of a fabric objectively. It quantitatively describes fabric hand by using translation result from some measured values of relevant attributes of a fabric. Techniques used for objective hand evaluations are based on special instruments for

Several attempts have been made to measure fabric handle properties objectively described simply as "Fabric Objective Measurement (FOM)", and also a number of items of equipment

The KES-F system (Kawabata's Hand Evaluation System for Fabrics) was developed in Japan by the Hand Evaluation and Standardization Committee (HESC, established in 1972)

have been introduced for this purpose (Hasani & Planck, 2009; Bishop, 1996).

**4.2 Objective evaluation of fabric handle** 

in Kawabata et al., 1973; as cited in Kawabata et al., 1996).

measuring handle related properties (Bakar, 2004).

**4.2.1 Objective measurement systems** 

organized by Professor Kawabata. In this fabric objective measurement method, scientific principles are applied to the instrumental measurement and fabric low stress mechanical and surface properties such as fabric extension, shear, bending, compression, surface friction and roughness are measured. The fabric handle is calculated from measurements of these properties. Empirical equations for calculating primary hand values and total hand values were put forward by Kawabata and Niwa (Mäkinen et al., 2005; as cited in Kawabata, 1980; as cited in Shishoo, 2000).

The process of the subjective evaluation according to Kawabata can be given as follows (Bona, 1994):


The first part of Kawabata`s work was to find the important aspects of handle and the contribution of each to the overall rating of the fabric. For each category such as stiffness, smoothness, etc. were identified and the title of primary hand values were give. The original Japanese terms of these primary hand definitions together with English meanings are given in Table 4. The primary hand values are combined to give an overall rating for the fabric categories such as man's summer suiting, man's winter suiting, lady's thin dress, and man's dress short and knitted fabrics for undershirts. The conversion of the primary hand values is done by using a translation equation for a particular fabric category determined empirically. This total hand value is rated on a five point scale, where five is the best rating (Kawabata, 1980).

The second stage of Kawabata`s work was to produce a set of instruments with which to measure the appropriate fabric properties and then to correlate these measurements with the subjective assessment of handle. The aim was that the system would then enable any operator to measure reproducibility the total hand value of a fabric (Saville, 1999).

The Kawabata Evaluation System for Fabric (KES-F) which has been widely used since the 1970's consists of four specialized instruments: FB1 for tensile and shearing, FB2 for bending, FB3 for compression and FB4 for surface friction and variation. A total of 16 parameters are measured at low levels of force (Table 5). The measurements are intended to simulate the fabric deformations found in use (Hu, 2008; Chen et al., 2001).

Fig. 7. Measuring principles of the KES system

Sensorial Comfort of Textile Materials 251

Fig. 8. (a) Load extension recovery curve (b) Hysteresis curve for shear (Saville, 1999)

Linearity of load-extension curve

Hysteresis of bending moment

Linearity of pressure-thickness curve

Hysteresis of shear force at 0.5º shear angle Hysteresis of shear force at 5º shear angle

Mean deviation of MIU, frictional roughness

Tensile energy Tensile resilience

Shear rigidity

Bending rigidity

Compressional energy Compressional resilience

Coefficient of friction

Geometrical roughness

LT WT RT

G 2HG 2HG5

2HB

MIU MMD SMD

quantities are then measured from the curve as shown in Figure 8b.

Force hysteresis at shear angle of 0.5° 2HG = hysteresis width of curve at 0.5° Force hysteresis at shear angle of 5° 2HG5 = hysteresis width of curve at 5°

Shear stiffness G = slope of shear force-shear strain curve

**Weight** W Weight per unit area **Thickness** T Thickness at 0.5 gf/cm2 Table 5. Characteristic values in KES-F system (Mäkinen et al., 2005; as cited in Kawabata,

In order to measure the shear properties, a sample in dimensions of 5cm x 20cm is sheared parallel to its long axis keeping a constant tension of l0 gf/cm on the clamp. The following

LC WC RC

Tensile energy *WT* = the area under the load strain curve (load increasing)

Resilience RT=area under load decreasing curve /*WT* x 100

**Characteristic values measured in KES-F system** 

**Tensile** 

**Shearing** 

**KES- FB2 Bending** <sup>B</sup>

**KES- FB3 Compression** 

**KES- FB4 Surface** 

**KES- FB1** 

**Fabric construction** 

1980)

Linearity *LT=WT*/area triangle *OAB*


Table 4. The definitions of primary hand (Kawabata, 1980)

The characteristic values are calculated from recorded curves obtained from each tester both in warp and weft direction. Tensile properties (force-strain curve) and shear properties (force-angle curve) are measured by the same apparatus. Bending properties (torque-angle curve) are measured by bending first reverse sides against each other and after that the face sides against each other. Pressure-thickness curves are obtained by compression tester. The measurements of surface friction (friction coefficient variation curve) and surface roughness (thickness variation curve) are made with the same apparatus using different detectors.

The tensile properties are measured by plotting the force extension curve between zero and a maximum force of 500 gf/cm, the recovery curve as the sample is allowed to return to its original length is also plotted to give the pair of curves shown in Figure 8a. From these curves the following values are calculated (Saville, 1999):

A stiff feeling from bending property. Springy property promotes this feeling. High-density fabrics made by springy and elastic yarn usually possess this

A mixed feeling come from smooth and soft feeling. The fabric woven from cashmere fiber gives this feeling

A bulky, rich and well-formed feeling. Springy property in compression and the thickness accompanied with warm feeling are closely related with this feeling *(fukurami* means 'swelling').

A feeling of a crisp and rough surface of fabric. This feeling is brought by hard and strongly twisted yarn. This gives a cool feeling. This word means crisp, dry and sharp sound made by rubbing the

Anti-drape stiffness, no matter whether the fabric is springy or not. (This word

fabric surface with itself).

possesses this feeling strongly.

flexible and smooth feeling.

means 'spread').

*Kishimi* **Scrooping feeling** Scrooping feeling. A kind of silk fabric

The characteristic values are calculated from recorded curves obtained from each tester both in warp and weft direction. Tensile properties (force-strain curve) and shear properties (force-angle curve) are measured by the same apparatus. Bending properties (torque-angle curve) are measured by bending first reverse sides against each other and after that the face sides against each other. Pressure-thickness curves are obtained by compression tester. The measurements of surface friction (friction coefficient variation curve) and surface roughness (thickness variation curve) are made with the same apparatus using different detectors.

The tensile properties are measured by plotting the force extension curve between zero and a maximum force of 500 gf/cm, the recovery curve as the sample is allowed to return to its original length is also plotted to give the pair of curves shown in Figure 8a. From these

*Shinayakasa* **Flexibility with soft feeling** Soft, flexible and smooth feeling. *Sofutosa* **Soft touch** Soft feeling. A mixed feeling of bulky,

feeling strongly.

strongly.

**Hand Definition Japanese English** 

*Koshi* **Stiffness** 

*Numeri* **Smoothness** 

*Shari* **Crispness** 

*Fukurami* **Fullness and softness** 

*Hari* **Anti-drape stiffness** 

Table 4. The definitions of primary hand (Kawabata, 1980)

curves the following values are calculated (Saville, 1999):

Tensile energy *WT* = the area under the load strain curve (load increasing)

Linearity *LT=WT*/area triangle *OAB*

Resilience RT=area under load decreasing curve /*WT* x 100

Fig. 8. (a) Load extension recovery curve (b) Hysteresis curve for shear (Saville, 1999)


Table 5. Characteristic values in KES-F system (Mäkinen et al., 2005; as cited in Kawabata, 1980)

In order to measure the shear properties, a sample in dimensions of 5cm x 20cm is sheared parallel to its long axis keeping a constant tension of l0 gf/cm on the clamp. The following quantities are then measured from the curve as shown in Figure 8b.

Shear stiffness G = slope of shear force-shear strain curve

Force hysteresis at shear angle of 0.5° 2HG = hysteresis width of curve at 0.5°

Force hysteresis at shear angle of 5° 2HG5 = hysteresis width of curve at 5°

Sensorial Comfort of Textile Materials 253

for the population within which the data were taken but there is some question as to the application of the same weighing factors in a different culture (Adanur, 2001). Critics still exist due to the high cost of the instrument. The system also requires experts for the interpretation of the resulting data. These deficiencies led to the development of another

The Australian CSIRO designed and developed the FAST (Fabric Assurance by Simple Testing) set of instruments, as a simpler alternative to a KES system, which in terms of practicality and testing speed, go a long way towards meeting the requirements of garment makers, finishers and is designed to be relatively inexpensive, reliable, accurate, robust and simple to operate. Unlike the KES-F system, FAST only measures the resistance of fabric to deformation and not the recovery of fabric from deformation (Shishoo, 1995; Behery, 2005;

FAST gives similar information on the aesthetic characteristics of fabric as KES-F does, but in a simple manner, and is more suited to a mill environment. The FAST system includes FAST-1 for thickness, FAST-2 for bending, FAST-3 for extensibility and FAST-4 for dimensional stability. Through the objective measurements of fabric and a data set on a chart or 'fingerprint', manufacturers can identify fabric faults, predict the consequences of

**Characteristics measured in FAST system Symbol Unit Device** 

Bending Bending length B FAST-2

Weft elongation Crosswise elongation

Hygral expansion

FAST-1 is a compression meter enabling the measurement of fabric thickness and surface thickness at two predetermined loads (Hu, 2004). The fabric thickness is measured on a 10 cm2 area at two different pressures, firstly at 2 gf/cm2 and then at 100 gf/cm2. This gives a measure of the thickness of the surface layer which is defined as the difference between these two values (Figure 11a). The fabric is considered to consist of an incompressible core

FAST-2 is a bending meter, which measures the bending length of the fabric. From this measurement, the bending rigidity of the fabric can be calculated. The instrument uses the cantilever bending principle described in BS: 3356. However, in FAST-2 the edge of the fabric is detected using a photocell. The bending rigidity, which is related to the perceived stiffness, is calculated from the bending length and mass/unit area. (Saville, 1999; Hu,

Surface thickness ST mm

E

RS HE mm

% % %

%

FAST-1

FAST-3

% FAST-4

those faults and identify re-finishing routes or changes in production (Hu, 2008).

Fabric weight W g/m2

testing device called the FAST (Hu, 2004).

Mazzuchetti et al., 2008; Potluri et al., 1995).

Compression Total thickness

Tensile Warp elongation

Dimensional stability Relaxation shrinkage

and a compressible surface (Saville, 1999).

2004).

Table 6. List of fabric properties measured using FAST (Saville, 1999)

In order to measure the bending properties of the fabric, the sample is bent between the curvatures -2.5 and 2.5 cm-1, the radius of the bend is the reciprocal of the curvature as shown in Figure 9a. The bending moment required to give this curvature is continuously monitored to give the curve as shown in Figure 9b (Saville, 1999).

Compressibility is one of the most important properties in terms of fabric handle for the fabrics used in garment manufacture (Mukhopadyhay et al., 2002). The compression test for fabric is used to determine the fabric thickness at selected loads, and reflects the 'fullness' of a fabric (Hu, 2008).

The compression energy, compressibility, resilience and thickness of a specimen can be obtained by placing the sample between two plates and increasing the pressure while

Fig. 9. a) Forces involving in fabric bending; b) Plot of bending moment against curvature (Saville, 1999)

continuously monitoring the sample thickness up to a maximum pressure of 50 gf/cm2. A circular compressing board of 2 cm2 attached with a sensor is used to apply the force on the fabric specimen (Figure 10) (Saville, 1999).

Fig. 10. Compression test on the KES-F system (Hu, 2008)

The surface friction is measured in a similar way by using a contactor which consists of ten pieces of the same wire as used in the surface roughness. A contact force of 50 gf is used in this case and the force required to pull the fabric past the contactor is measured. For the surface roughness, the contact force that the wire makes with the surface is 10gf (Chen et al., 2001).

Kawabata developed through extensive human subjective evaluations of a range of fabric types and the ranking of characteristics. The weighing factors are believed to be appropriate

In order to measure the bending properties of the fabric, the sample is bent between the curvatures -2.5 and 2.5 cm-1, the radius of the bend is the reciprocal of the curvature as shown in Figure 9a. The bending moment required to give this curvature is continuously

Compressibility is one of the most important properties in terms of fabric handle for the fabrics used in garment manufacture (Mukhopadyhay et al., 2002). The compression test for fabric is used to determine the fabric thickness at selected loads, and reflects the 'fullness' of

The compression energy, compressibility, resilience and thickness of a specimen can be obtained by placing the sample between two plates and increasing the pressure while

Fig. 9. a) Forces involving in fabric bending; b) Plot of bending moment against curvature

continuously monitoring the sample thickness up to a maximum pressure of 50 gf/cm2. A circular compressing board of 2 cm2 attached with a sensor is used to apply the force on the

The surface friction is measured in a similar way by using a contactor which consists of ten pieces of the same wire as used in the surface roughness. A contact force of 50 gf is used in this case and the force required to pull the fabric past the contactor is measured. For the surface roughness, the contact force that the wire makes with the surface is 10gf (Chen et al.,

Kawabata developed through extensive human subjective evaluations of a range of fabric types and the ranking of characteristics. The weighing factors are believed to be appropriate

monitored to give the curve as shown in Figure 9b (Saville, 1999).

a fabric (Hu, 2008).

(Saville, 1999)

2001).

fabric specimen (Figure 10) (Saville, 1999).

 Fig. 10. Compression test on the KES-F system (Hu, 2008) for the population within which the data were taken but there is some question as to the application of the same weighing factors in a different culture (Adanur, 2001). Critics still exist due to the high cost of the instrument. The system also requires experts for the interpretation of the resulting data. These deficiencies led to the development of another testing device called the FAST (Hu, 2004).

The Australian CSIRO designed and developed the FAST (Fabric Assurance by Simple Testing) set of instruments, as a simpler alternative to a KES system, which in terms of practicality and testing speed, go a long way towards meeting the requirements of garment makers, finishers and is designed to be relatively inexpensive, reliable, accurate, robust and simple to operate. Unlike the KES-F system, FAST only measures the resistance of fabric to deformation and not the recovery of fabric from deformation (Shishoo, 1995; Behery, 2005; Mazzuchetti et al., 2008; Potluri et al., 1995).

FAST gives similar information on the aesthetic characteristics of fabric as KES-F does, but in a simple manner, and is more suited to a mill environment. The FAST system includes FAST-1 for thickness, FAST-2 for bending, FAST-3 for extensibility and FAST-4 for dimensional stability. Through the objective measurements of fabric and a data set on a chart or 'fingerprint', manufacturers can identify fabric faults, predict the consequences of those faults and identify re-finishing routes or changes in production (Hu, 2008).


Table 6. List of fabric properties measured using FAST (Saville, 1999)

FAST-1 is a compression meter enabling the measurement of fabric thickness and surface thickness at two predetermined loads (Hu, 2004). The fabric thickness is measured on a 10 cm2 area at two different pressures, firstly at 2 gf/cm2 and then at 100 gf/cm2. This gives a measure of the thickness of the surface layer which is defined as the difference between these two values (Figure 11a). The fabric is considered to consist of an incompressible core and a compressible surface (Saville, 1999).

FAST-2 is a bending meter, which measures the bending length of the fabric. From this measurement, the bending rigidity of the fabric can be calculated. The instrument uses the cantilever bending principle described in BS: 3356. However, in FAST-2 the edge of the fabric is detected using a photocell. The bending rigidity, which is related to the perceived stiffness, is calculated from the bending length and mass/unit area. (Saville, 1999; Hu, 2004).

Sensorial Comfort of Textile Materials 255

Shirley stiffness tester and circular bending rigidity tester for bending properties, cusick drape meter and sharp corner drape meter for drape properties, universal tensile testers for tensile and shear properties, thickness gauges for thickness and compression properties, universal surface tester and Frictorq for friction properties can be listed as commonly used simpler devices for measuring handle related properties of textile materials. Fabric extraction method and devices such as Griff-Tester (Kim & Slaten, 1999; Strazdienė & Gutauskas, 2005), robotic handling systems (Potluri et al., 1995) and various individual

Cantilever stiffness tester supplies an easy way for measuring the fabric stiffness (Figure 13a). In the test, a horizontal strip of fabric is slid at a specified rate in a direction parallel to its long dimension, until its leading edge projects from the edge of a horizontal surface. The length of the overhang is measured when the tip of the specimen is depressed under its own mass to the point where the line joining the top to the edge of the platform makes a 41.5° angle with the horizontal. It is known as bending length (Figure 13b) and from this measured length, the flexural rigidity is calculated by using the formula given below (ASTM

*G = 1.421 x 10-5 x W x c3* ; where: *G* = flexural rigidity (μjoule/m), *W* = fabric mass per unit

(a) (b)

The cantilever method is not suitable for the fabrics that are too limp or show a marked tendency to curl or twist at a cut edge. The heart loop test can be used for these fabric types. A strip of fabric is formed into a heart-shaped loop. The length of the loop is measured when it is hanging vertically under its own mass (ASTM D 1388–08). The undistorted length of the loop *lo*, from the grip to the lowest point is calculated (Saville, 1999; as cited in Peirce, 1930) for three different loop shapes: the ring, pear and heart shapes. If the actual length *l* of

Fig. 13. (a) Cantilever stiffness tester, (b) Bending length (Saville, 1999)

Fig. 14. Different shapes of hanging loops (Saville, 1999)

**Ring Loop**: *l0* =0.3183 *L* θ = 157º *(d/l0)*

Bending length *C*= *L 0.133 f2(θ)*  **Pear loop**: *l0* =0.4243 *L* θ = 504.5º *(d/l0)* Bending length *C*= *L 0.133 f2(θ) / cos 0.87 (θ)*  **Heart loop:** *l0* =0.1337*L* θ = 32.85º *(d/l0)* Bending length *C*= *l0 f2(θ) f2(θ)=*(cosθ/tanθ) *1/3* devices are some of the other objective measurement systems (Özçelik et al., 2008).

**4.2.2 Individual objective measurement testers** 

area (g/cm2) and *c* = bending length (mm).

D 1388).

Fig. 11. (a) Measuring principle of the FAST-1 compression meter; (b) Measuring principle of the FAST-2 bending meter (Hu, 2004)

FAST-3 is an extension meter which operates on a simpler principle as shown in Figure 12a (Hu, 2004). The extension of the fabric is measured in the warp and weft directions at three fixed forces of 5, 20 and l00 gf/cm (sample size tested 100mm x 50mm). The extension is also measured on the bias in both directions but only at a force of 5gf/cm, this enables the shear rigidity to be calculated (Saville, 1999).

Fig. 12. (a) Measuring principle of the FAST-3 extension meter (Hu, 2004); (b) Dimensional stability curve (Bona, 1994)

The final component of FAST is a test method which measures the changes in the dimensions of fabrics that occur when the fabric is exposed to changing environmental conditions (Hu, 2004). A small amount of shrinkage (usually below 1%) is required for fabrics intended to be pleated. In order to measure dimensional stability the fabric is dried in an oven at 105ºC and measured in both warp and weft directions to give the length L1. It is then soaked in water and measured wet to give the wet relaxed length L2. It is then redried in the oven and measured again to give the length L3. The following values for dimensional stability are then calculated from these measurements for both warp and weft.

$$\text{Relaxation shrinkage} = \frac{L\_1 - L\_3}{L\_1} \text{x100(\%)} \quad \text{Hygral expansion} = \frac{L\_2 - L\_3}{L\_3} \text{x100(\%)}$$

Since the sensation is related to physical properties of the material, physical measurements constitute significant data in terms of objective evaluation. Disadvantages of the complex measuring systems such as high costs, difficulties in maintenance and reparation have resulted in conducting studies on improving simpler and individual instruments for each handle related objective fabric properties (Ozcelik et al., 2008).

the FAST-2 bending meter (Hu, 2004)

rigidity to be calculated (Saville, 1999).

stability curve (Bona, 1994)

(a) (b) Fig. 11. (a) Measuring principle of the FAST-1 compression meter; (b) Measuring principle of

FAST-3 is an extension meter which operates on a simpler principle as shown in Figure 12a (Hu, 2004). The extension of the fabric is measured in the warp and weft directions at three fixed forces of 5, 20 and l00 gf/cm (sample size tested 100mm x 50mm). The extension is also measured on the bias in both directions but only at a force of 5gf/cm, this enables the shear

 (a) (b) Fig. 12. (a) Measuring principle of the FAST-3 extension meter (Hu, 2004); (b) Dimensional

The final component of FAST is a test method which measures the changes in the dimensions of fabrics that occur when the fabric is exposed to changing environmental conditions (Hu, 2004). A small amount of shrinkage (usually below 1%) is required for fabrics intended to be pleated. In order to measure dimensional stability the fabric is dried in an oven at 105ºC and measured in both warp and weft directions to give the length L1. It is then soaked in water and measured wet to give the wet relaxed length L2. It is then redried in the oven and measured again to give the length L3. The following values for dimensional stability are then calculated from these measurements for both warp and weft.

Since the sensation is related to physical properties of the material, physical measurements constitute significant data in terms of objective evaluation. Disadvantages of the complex measuring systems such as high costs, difficulties in maintenance and reparation have resulted in conducting studies on improving simpler and individual instruments for each

2 3

3

 Hygral expansion 100 *L L x (%) <sup>L</sup>* 

1 3 1

Relaxation shrinkage 100 *L L x (%) <sup>L</sup>*

handle related objective fabric properties (Ozcelik et al., 2008).
