Those engaged in the production, distribution, and consump- tion of textiles, testing can be a valuable aid provided that the instruments and techniques are used effectively. When tests are made the results must be studied carefully so that the right course of action may be taken. Testing instruments cannot make decisions, and in the end some person has to interpret the data and issue the necessary instructions for future action. Testing is, therefore, a means to an end and not an end in itself. The fact that a material has been tested, no matter how accurately, does not enhance its technical quality
1. Yarn Count
The yarn numbering system, used to express a relationship between a unit length and weight of yarns. Thus count defines the fineness of yarn used in fabric.
This system is divided into two main systems.
- Direct System
- Indirect System
Cotton Count = No. of yarn x length of yarn (cm)
169 X Weight of Yarn (gm)
Conversion of Counts
Denier (D) = 5315 / Cotton Count
Tex (Tex) = 590.5/ Cotton Count = 0.111 x Denier
2. Fabric Construction
It defines the density of fabric weave in terms of yarns per inch in warp and weft direction. Fabric construction has an influence on the weight of fabric. Measured in EPI & PPI
3. Dimensional Stability
It determines the change in dimension in length and width of the fabric as a result of shrinkage or expansion after repeated home laundering or dry-cleaning.
The degree of shrinkage depends on the type of the fiber, fabric construction, and temperature of washing and drying.
4. Appearance
It assesses the visual appearance of textile product and color change after repeated home laundering or dry cleaning. The test uses standard scales or replicas to evaluate the amount the change in the appearance.
5. Spirality / Skewness
Angular deviation in length and width direction of the fabric due to twisting of fabric or garments is known as Spirality / Skewness.
B’ B
X A Y
% Skewness = BB’ C 100
AB
6. Colorfastness to Laundering / dry-cleaning:
It refers to the ability of a colorant on a fabric/Garment to withstand by the effects of Laundering or dry cleaning.
A sample of textile fabric sewn with Multifiber test fabric is mechanically agitated in launder-o-meter under specified conditions of time and temperature in soap solution and steel balls then rinsed & dried. The color change of the sample and staining of the Multifiber is assessed with grey scales under standard viewing environment.
7. Colorfastness to Rubbing / Crocking:
It determines the resistance of the color of textiles to rubbing off and staining on white fabrics. Both dry and wet rubbing tests are conducted. The staining of the rubbing cloth is assessed with grey scales under standard environment.
A standard test device, Crock meter is used for this test.
8. Colorfastness to Perspiration:
It shows the effect of human perspiration on fabric in terms of color change and staining. Perspiration tester and hot air oven are used to simulate the body temperature and prolonged body contacts on fabrics. Textile samples and adjacent fabrics are treated in simulated perspiration liquor. The dried sample and adjacent fabric are assessed by grey scales on color change and color staining.
Sports shirts and underwear are necessary for this test.
9. Colorfastness to Light:
It refers to the ability of colorant on fabric to withstand the effects of sunlight. This test is conducted on Atlas Fadometer, which simulate the sunlight and environment on samples by controlling the irradiance, temperature and relative humidity within the equipments.
Exposure is done for a specific period of time (i.e. 20,40,80 hrs etc.) for AATCC standards. And then the sample is assessed for color change with the grey scales.
Swimwear, Sportswear and garments frequently exposed to sunlight should be specially checked for this test.
10. Colorfastness to Non-chlorine Bleach
This test method is designed to evaluate the colorfastness performance of a textile fabric when subjected to the action of usually market available type detergent containing non-chlorine bleach.
A specimen is introduced with a drop of diluted non-chlorine bleach assessed for color change by grey scales.
11. Tensile Strength
It determines the strength of a fabric when subjected to tension by external force. It is measured by the minimum amount of such a force required to rupture a fabric.
12. Tear Strength
It measures an average force required to propagate a tear after a cut mark in the fabric.
For this test Elmendorf tearing tester is used which indicates the degree of damage on fabric. This is generally applicable to bleached, resin treated or coated woven fabrics.
13. Bursting Strength
It is the radial force needed to rupture a fabric by distending it at right angle to the materials. This is especially desirable to test knits, and non-woven fabrics.
In knit fabric, there is no specific warp & weft as woven fabric, so multidirectional force is applied on it
14. Abrasion Resistance
It determines the durability of fabrics under abrasion in simulated fabric rubs against fabric. Its also called “Wear & Tear test”
The end point of the abrasion is evaluated either by the yarn broken or color change.
15. Pilling Resistance
Pilling is the formation of balls of entangled fibers on the textile surface due to rubbing. This pill formation may affect the appearance of garments. Test is conducted on Random pilling tumbler.
Short and hairy fibers such as wool have high tendency to form pills.
16. Stretch & Recovery
The test is used to evaluate the elastic properties as elongation & recovery. This is a cyclic test and conducted on Universal Testing Machine.
Stretch fabrics can elongate to a greater extent degree than ordinary fabrics.
17. Blend Analysis
This test is to identify the fiber and the actual content of different kind of fibers used in the manufacturing of textile product.
The fiber is identified by studying microscopic longitudinal and cross-sectional view or chemically.
Fibers are identified by using three techniques
- Microscopic view
- Burning Test
- By physical Separation or Dissolving In Chemicals
18. pH
Its one of the critical factor for processed fabric and especially applicable to white colored fabrics.
This test is to define the acidity & alkalinity of textiles.
Assessment of Colorfastness
Grey Scale for Staining on Multifiber
All colorfastness/appearance samples are evaluated against two parameters
- Color Change
- Staining on Multifiber
This evaluation of tested specimen is done by the Grey scale ranging from 1 to 5.
Interpretation of these grey scale values are given below
Grade 1 : Very severe staining
Grade 2 : Severe
Grade 3 : Noticeable
Grade 4 : Slight
Grade 5 : No Staining