Textile Testing and Quality Control Part-B

Importance of Textile Testing | Reasons for Testing of Textile

The testing of textile products is an expensive business. A laboratory has to be set up and furnished with a range of test equipment. Trained operatives have to be employed whose salaries have to be paid throughout the year, not just when results are required. Moreover all these costs are nonproductive and therefore add to the final cost of the product. Therefore it is important that testing is not undertaken without adding some benefit to the final product. There are a number of points in the production cycle where testing may be carried out to improve the product or to prevent sub-standard merchandise progressing further in the cycle.

Importance of Textile Testing:

The primary objective of textile testing is to assess the product properties and predict its performance during use. The information obtained may be used for the following:

1. Research and development
2. Selection of raw materials/inputs
3. Process development
4. Process control
5. Quality control
6. Product testing
7. Product failure analysis
8. Comparative testing and bench marking
9. Conformity with government regulations and specifications

Reasons for Textile Testing

1. Checking Raw Materials
2. Monitoring Production
3. Assessing the Final Product
4. Investigation of Faulty Material
5. Product Development and Research

Checking Raw Materials

The production cycle as far as testing is concerned starts with the delivery of raw material. If the material is incorrect or sub-standard then it is impossible to produce the required quality of final product. The textile industry consists of a number of separate processes such as natural fiber production, man-made fiber extrusion, wool scouring, yarn spinning, weaving, dyeing and finishing, knitting, Home textile manufacture and production of household and technical products. These processes are very often carried out in separate establishments, therefore what is considered to be a raw material depends on the stage in processing at which the testing takes place. It can be either the raw fibre for a spinner, the yarn for a weaver or the finished fabric for a Home textile maker. The incoming material is checked for the required properties so that unsuitable material can be rejected or appropriate adjustments made to the production conditions. The standards that the raw material has to meet must be set at a realistic level. If the standards are set too high then material will be rejected that is good enough for the end use, and if they are set too low then large amounts of inferior material will go forward into production.

Monitoring Production

Production monitoring, which involves testing samples taken from the production line, is known as quality control. Its aim is to maintain, within known tolerances, certain specified properties of the product at the level at which they have been set. A quality product for these purposes is defined as one whose properties meets or exceeds the set specifications. Besides the need to carry out the tests correctly, successful monitoring of production also requires the careful design of appropriate sampling procedures and the use of statistical analysis to make sense of the results.

Assessing the Final Product

In this process the bulk production is examined before delivery to the customer to see if it meets the specifications. By its nature this takes place after the material has been produced. It is therefore too late to alter the production conditions. In some cases selected samples are tested and in other cases all the material is checked and steps taken to rectify faults. For instance some qualities of fabric are inspected for faulty places which are then mended by skilled operatives; this is a normal part of the process and the material would be dispatched as first quality.

Investigation of Faulty Material

If faulty material is discovered either at final inspection or through a customer complaint it is important that the cause is isolated. This enables steps to be taken to eliminate faulty production in future and so provide a better quality product. Investigations of faults can also involve the determination of which party is responsible for faulty material in the case of a dispute between a supplier and a user, especially where processes such as finishing have been undertaken by outside companies. Work of this nature is often contracted out to independent laboratories who are then able to give an unbiased opinion.

Product Development and Research

In the textile industry technology is changing all the time, bringing modified materials or different methods of production. Before any modified product reaches the market place it is necessary to test the material to check that the properties have been improved or have not been degraded by faster production methods. In this way an improved product or a lower-cost product with the same properties can be provided for the customer. A large organization will often have a separate department to carry out research and development; otherwise it is part of the normal duties of the testing department.

Color Fastness Test to Light | Light Fastness Grades

The purpose of Color fastness to light test is to determine how much the color will fade when exposed to a known light source. It is an off line quality assurance system. Generally man wears the fabric and goes outside of the home for doing their job. In day; sun light fall on the fabric surface. So it needs to know how much protection ability have a fabric to sun light. It is determined by an experiment called color fastness to light. To measure the color fastness a blue scale is used. After completing the test, sample is compared with the blue scale.

Principle of Color Fastness to Light:

This test measures the resistance to fading of dyed textile when exposed to day light. The test sample is exposed to light for a certain time which is about 24 hours to 72 hours or by customer/buyer demand and compare the change with original unexposed sample the changes are assessed by Blue Scales.

Color Fastness to Light with the Microsol light Fastness Tester:

The testing is done step by step. Following step is maintained during measure the color fatness to light.

1. Cut the four pieces of test specimens according to the length & width wise and attached with the specimen holder.
2. Then the holder set in to the Microsol light fastness tester.
3. Then the experiment continued at 72 hours according to the buyer’s requirement.
4. After 72 hours later the specimen taken from the light fastness tester
5. Then the test specimen compare with the Blue scale or computer color matching system (CCMS).

Introduction of Pressing Fastness Test | Color Fastness to Pressing

Color Fastness to Pressing:

Pressing fastness test of dyed and printed textile products is performed to determine of resistance of textiles to ironing and to processing on cylinders. Different tests are performed according to when the textile is dry, when it is wet, and when it is damp.

Purpose and Scope:

This method is used for determining the resistance of the color of textile of all kinds and in all forms to ironing and processing on hot cylinders. Tests are given for hot pressing when the textiles are wet, when it is damp, and when it is dry.

Apparatus and Reagent 

Hand iron of proper weight to give a pressure of approximately 30g/sq.cm at the temperature indicated in the following;

• Cotton & Linen 190-200C˚
• Wool, Silk & Viscose 140-160C˚
• Cellulose acetate & Polyamide 115-120C˚
• White bleached cotton cloth weighting approximately 125g/sq.meter. Five pieces not less than 14×4 cm are required.
• Gray scale by assessing change in colour and staining.(ISO scale)
• The size of the specimen is 10×4cm

Working Procedure

Specimen preparation

Specimen of materials, which has been subjected to any heat or drying treatment, must be allowed to condition at 65% RH, temp. 20±2C˚, before they tested.

Dry Pressing

Place the specimen on the piece of dry cotton cloth on a smooth horizontal surface. Place the iron on the specimen and leave it for 15 Sec.

Damp Pressing:

The adjacent fabric in dimensions of 100 mm x 40 mm is immersed into the water and, squeezed as 100% pick up. Dry specimen is placed onto the undyed cotton fabric on the filler and, the wet adjacent fabric is placed onto them. The top layer of the device is pulled down and, dry specimen is pressed for 15 seconds at the determined temperature. The change in color of the specimen is evaluated in two different ways according to grey scale.

1. a) Soon after the end of the test
2. b) After conditioning for 4 hours under standard atmospheric circumstances.

The staining to undyed fabrics is evaluated by grey scale.

 Wet Pressing

Soak the specimen and cotton cloth in distilled water and squeeze or extract them to contain their own weight of water. Place the wet specimen on a piece of the dry cotton cloth and place the wet cotton cloth on the specimen, press by moving the iron to and fro over the wet cloth (without additional pressure) for 15 sec.

Assessment

Assess the change in color of the specimen with appropriate grey scale.

Standard

Dry Pressing 4

Wet Pressing 3-4

Introduction of Perspiration Test | Color Fastness to Perspiration

The color fastness to perspiration (acid and alkaline) shall be at least level 3-4 (color change and staining). This criterion does not apply to white products, to products that are neither dyed nor printed, to furniture fabrics, curtains or similar textiles intended for interior decoration. A level of 3 is nevertheless allowed when fabrics are both light colored (standard depth < 1/12) and made of silk or of blends with more than 20% silk. This kind of test is specially applied for the sportswear and heavy dresses which is used specially. Normal cloths is also tested by perspiration test.

Color Fastness to Perspiration

The Home textiles which come into contact with the body where perspiration is heavy may suffer serious local discoloration. This test is intended to determine the resistance of color of dyed textile to the action of acidic and alkaline perspiration. Before knowing about the Color Fastness to perspiration you must have to know about Color Fastness to Wash and Color Fastness to Rubbing.

Perspiration matters which effects on Color fastness.

Purpose and Scope

This method is used to determine the resistance of the color of textile of all kinds and in all forms to perspiration.

Equipment for Fastness Measurement

1. Perspiration tester
2. Oven, Maintained at 37+-2 Degree centigrade
3. Multi fiber test fabric
4. Grey scale
5. Color matching chamber
6. Acidic and Alkaline solution
7. Glass or Acrylic plat

Reagent for Perspiration Test

1. Solution freshly prepared, containing 0.5g 1-histidine mono-hydrochloride mono-hydrate, 5g sodium chloride, and 2.5g disodium hydrogen ortho phosphate per litre brought to PH 8.0 with 0.1N sodium hydroxide.
2. Solution freshly prepared, containing 0.5g 1-histidine mono-hydrochloride mono-hydrate, 5g sodium chloride, and 2.2g sodium dihydrogen ortho phosphate per litre brought to PH 5.5 with 0.1N sodium hydroxide.
3. Two undyed cloths for each specimen each 6×6cm of the same kind of fibre as the sample. Place the specimen between the two pieces of white cloth and sew along one side to form a composite sample.

Working Procedure:

1. Thoroughly wet one composite sample in a solution of PH8.0 at the liquor ratio of 20:1 and allow it to remain in this solution at room temperature for 30min. pour off the solution and place the composite sample between two glasses plates measuring about 7.5×6.5cm under a force of about 4.5kg.
2. Treat the other sample in the same way but with the solution at PH 5.5.
3. Place the apparatus containing the samples in the oven for 4 hour at 37±2C˚
4. Separate the sample from the white cloth and dry them apart in air at the temperature not exceeding 60C˚
5. Assess the change in color of the specimen and the staining of the white cloth with the greigh scale.

A fastness is a place, such as a castle, which is considered safe because it is difficult to reach or easy to defend against attack. This test is designed to determine the degree of color which may be transferred from the surface of a colored fabric to a specify test cloth for rubbing (which could be dry and Wet).

There are two test methods for rubbing fastness.

1. ISO-105-X12
2. AATCC-08

In ISO-105-X12 the wet pickup of the rubbing cloth is 100% .While in AATCC-08 the wet Pickup of the rubbing cloth is 65%.We check rubbing by Dry and Wet methods. In wet rubbing we wet the rubbing cloth according to test method and give rating by comparing the Staining with the gray scale.

Similarly for dry rubbing we check the rubbing with dry rubbing cloth and compare the staining With gray scale for ratings .Color Fastness to rubbing is a main test which is always required for every colored fabric either it is Printed or dyed.

If the color fastness to rubbing is good then it’s other properties like washing fastness and durability etc. improves automatically because the rubbing is a method to check the fixation of the color on the fabric. So if the fixation is good it’s washing properties will be good.

Rubbing Fastness depends on:

1. Nature of the Color
2. Depth of the Shade
3. Construction of the Fabric Nature of the color Each color either it is pigment ,Reactive ,Disperse or direct has its own fastness properties to rubbing. There are some colors like black, Red ,Burgundy ,Navy blue which have poor Color fastness properties because of their chemical structure.
4. Like Black color is a carbon base color and the particle size of carbon is large than the other colors that’s why its rubbing properties are poor. Similarly red and blue are in the same case. So to improve the color fastness we add more binder to improve the fastness properties of these colors. It doesn’t mean that we can not achieve the best results with these colors. The required results can achieve but production cost will be increase. On the other hand the construction of the fabric also effects the fastness properties.

Rubbing fastness test

If the rubbing fastness on 100.80/40.40 is 3 on the gray scale it will be 2-3 on 52.52/22.22 with the same printing parameters. So always keep in mind these effects during finalize the required parameters with your customer.

Always Check

1. Quality construction
2. Color
3. Depth of the Color
4. End Use of the product

Results which we can achieve in Normal Conditions are:

1. Dark Shade
2. Medium shades
3. Light Shades

Dry                   wet

3-4                   2 -2.5

4                          3

4-5                 3.5-4

Color Fastness Test | Washing Fastness Test | Washing Fastness | Color Fastness to Washing

Color Fastness Test:

The property of a dye to retain its color when the dyed (or printed) textile material is exposed to conditions or agents such as light, perspiration, atmospheric gases, or washing that can remove or destroy the color. A dye may be reasonably fast to one agent and only moderately fast to another. Degree of fastness of color is tested by standard procedures. Textile materials often must meet certain fastness specifications for a particular use.

Washing Fastness Test

It is always useful and interesting to test the dye which is to be used on a sample of the yarn or fabric to be dyed. The outcome will depend on the fabric, the mordant that has been used and dye that has have been chosen. Testing is best carried out on a series of Groundnuts marked (for identification) samples, which have been mordant with a number of different mordents. Tests can be carried out for light, water and washing fastness using simple standard test methods.

To Test for Washing Fastness Follow these Steps:

1. Take two pieces of fabric about 5cm by 5cm, one of which is undyed cotton and the other undyed wool. Stitch them together along one side.
2. Take some sample strips of the dyed yarn and spread them evenly between the two pieces of cloth so that they overlap both sides. If dyed fiber is being tested a combed sample can be used in place of the yarn.
3. Sew around all four sides of the cloth so that the yarn is held in place.
4. Prepare a similar specimen with dyed materials that has satisfactory properties and place them in two jars with screw lids containing a solution of 5gm per liter soap or detergent solution at 30oC.
5. Agitate the two jars gently for 30mins, then remove the fabrics and wash them gently in clean water for 5mins. Open the stitching and separate the pieces to dry in air. Examination:
6. Place the dyed yarn next to a sample of the same material which has not been tested, and compare the change which has taken place. Compare also with the control sample with satisfactory properties. If the dyeing being tested shows equal or less change than the satisfactory sample, then it is as good as the satisfactory sample.
7. Place the wool and cotton cloths next to samples of the same material which have not been tested and compare them with the cloths that have been tested with a satisfactory dyeing. Equal or less staining shows equal or better fastness.

Washing Fastness Test | Wash Fastness | Description of Washing Fastness | Types of Washing Fastness

Color Fastness:

Color fastness is the ability of fabrics to retain the dyes used to color them. Some fabrics hold dye within their fibers extremely well – like denim – while others do not (mostly synthetic or artificial non-natural fabrics) and tend to “bleed” when they are washed. The denim would therefore be more “color fast” than the other fabric.

The resistance of a material to change in any of its color characteristics, when subjected to washing is called color fastness to washing.

General Principle:

A specimen of the textile to be tested, with the adjacent fabric attached is subjected to washing under specified conditions. to extent of any change in color and that of the staining of the adjacent fabric are assessed and the rating is expressed in fastness numbers.

There are two types of adjacent fabrics; (1) single fiber fabric and multiple fiber fabric. In the case of multi fiber fabric only one specimen is required and in the of single fiber fabric two adjacent fabric are required.

There are various colorfastness tests. Details of washing fastness tests are given below.

Fastness to Washing:

In the test, change in color of the textile and also staining of color on the adjacent fabric are assessed. A 10 x 4 cm swatch of the colored fabric is taken and is sandwiched between two adjacent fabric and stitched, The sample and the adjacent fabric are washed together. Five different types of washing are specified as different washing methods.

Washing fastness testing by Gyrowash

The solution for washing should be prepared to the required temperature of washing. The liquor material ratio is 50:1. After soaping treatment, remove the specimen, rinse twice in cold water and then in running cold water under a tap. Squeeze it and air dry at a temperature not exceeding 60°C. The change in color and staining is evaluated with the help of grey scales.