What causes Pilling in the Fabrics

Pilling is characterized by little balls of fibers attached on the fabric surface. These are entangled in nature and do not look good on the garment. These are caused by the fibers which got loose during washing and wearing. Due to rubbing action these take the form of a ball.

Pilling is always known in wool specially in garments with soft twisted yarns like Angora. However, with the emergence of synthetic fibers the tendency is aggravated.

What happens is that because the strength of the fibers which "anchor" the pills is low in the natural fibres, pills get formed and removed. But in case of synthetic fibers, which have more strength. the pills remain on the garment and accumulate and become worse.

Why pills get formed. It is due to migration of fibers from the yarn on to the surface of the fabric. So any treatment that reduces this migration tendency will reduce the pilling tendency. Thus increasing the twist in the yarn reduces the pilling tendency as it binds the fibers onto yarn.

The following are factors affecting Pilling

Fiber Factors

1. Fiber Nature: As explained natural fibers are less susceptible to pilling than synthetic

2. Fiber Fineness: Finer fibers are more susceptible to pilling as there is more propensity to bending. For example Angora is more susceptible to pilling than normal wool

3. Fiber Friction: More crimp in the fiber, less is the crimp as the migration tendency of the fibers is reduced.

4. Fiber Length: Shorter fibers are more susceptible to pilling as the migration of fibers is increased.

5. Fiber Strength: As explained earlier, strong fibers increase pilling tendency as there the pills find it hard to dislodge from the garment surface.

Yarn Factors 

1. Yarn Count: Coarser the count, more fibers are there in the cross section which leads to higher pilling tendency.

2. Yarn Twist: As explained earlier, more yarn twist leads to less crimp as it binds the fibers more and reduces its yarn tendency.

3. Yarn Finishing: Unsinged yarns have more tendency to pill.

4. Incompatible Blends: If the blend contains components that are incompatible with respect to fiber length and other parameters, tendency to pill increases.

Fabric Parameters

Closer fabric structures lead to less pilling.

If the fabric is subjected to long processes in finishing and processing there is more friction and hence more pilling is formed.

Use of anti-pilling finishes can reduce the tendency of pilling. 


Apart from technological factors, a few of the important factors for pilling are:

1. The person wearing the garment, if that person is particularly hard on garments, pilling tendency is more.
2. There are some susceptible parts of garments such as collars, cuffs, pocket edges which are more susceptible to pill, as there is more rubbing/chafing of the parts.

3. Garments which are frequently washed are more susceptible to pilling.

Testing of Pilling

A very nice introduction to pilling testing is dealt in this NPTEL lecture. 

Sources
1 2- Principles of Textile Testing- J. E. Booth


Buy my books at Amazon.com

About Tearing Strength of Fabrics

Tear strength is more important in the assessment of "serviceability" of the fabric. In order to tear a cloth, the threads are broken singly. It is therefore a frequent mode of fabric failure.

The factors which contribute to the resistance to the tear is :

a. Strength of the yarn normal to the tear.Suppose you are trying to tear the weft yarns. Then those yarns need to be stronger.

b. Freedom of movement of the yarn in the direction of the tear. As in a. The freedom of movement in the warp yarns should be there, which can be done by reducing the EPI.

There are two types of Tear strength measurement come into play. First is Initial Tear Strength: It is when the load is applied on the fabric to tear it. This load is always higher than the average tear strength. It is because of the fact that up to this load, yarn crimp removal and sliding takes place. But once this point is reached the load is instantly transferred to the successive yarns and the tear strength obtained is known as average tear strength. 

These are ways that the tear strength in a fabric can be affected:

1. By reducing the thread count in the direction opposite to the direction of test, the tearing strength can be increased. So if you are tearing warpways-means you are tearing weft yarn- reduce the thread count of warp yarn-means reduce EPI.

2. Use yarns with the high breaking load in the direction of test to increase tearing strength. Means take stronger yarns in weft, as in example in point 1. This is the most important factor.

3. Decrease friction between yarns to increase tearing testing strength. This allows threads to group closer together under the tearing force, so instead of the successive breakage of individual threads, the action becomes more of a strength test on plied yarns. Decreased friction allows this grouping.

4. Related to 3, is the effect of the weave. Thus a twill or 2/2 matt structure allows the threads to group better than a plain weave. So Twill or 2/2 exhibit better resistance to tearing than plain weave.

5. Related to the point 1, high sett fabrics preclude thread movement hence the assistance by thread group is reduced.

6. Special Finishes such as drip dry or crease resistance finishes may reduce tearing strengths.




Source: 1 , Textile Testing by Booth, 3,

Video below gives the tearing testing procedure:

Buy my books at Amazon.com

Can Wet Rubbing Fastness Greater than Dry Rubbing Fastness

Usually, Wet rubbing fastness ratings are lower than those of dry rubbing. However, there may be cases when it is reversed. As per Texanlab manual:

"This is sometimes observed in polyester fabrics. In these cases, the friction coefficient in wet crocking is lower than  dry crocking. Thus, in contrast to cotton, the colorfastness to wet crocking for polyester is higher than its colorfastness to dry crocking."

Other Resources:

1

How a Rubbing Fastness Tester Works. Watch this video:

Buy my books at Amazon.com

Technical Specifications of a Polyester Crepe Saree

A typical polyester crepe sari has  the warp and weft of 100% polyester of 75 denier, the TPM of warp and weft is 1800 S&Z alternate. No. of filaments in a yarn of both warp and weft is 70 each. EPI is 132 and PPI is 86. It has a width of  44.5 inches. GSM is 72.

The ideal quality requirements and tolerance are as given below:

1. Denier: + - 5%
2. Twist per meter: +/-5%
3. No. of filaments in yarn +/- 2
4. No. of Threads per inch in warp and weft: +5%/-2.5%
5. Width : +/- 0.5"
6. Length : +/-2 cm
7. GSM: +/-3%

Other Parameters

8. Breaking Strength on 5cm x 20 cm strip, N(KGf): Warp: 240 (24.4), Weft: 190 (19.3)
9. Tear Strength , N (kgf): Warp 20 (2.0), Weft 15 (1.5)
10. Color Fastness Rating due to Light ( Change in Color):5, Washing (Change in Color):4, Staining on adjacent fabric 3-4, Perspiration acidic and alkaline (Change in Color):4, staining on adjacent fabric:4,
Rubbing- Dry-4, Wet-3, Hot Pressing: change in color-4, Staining on adjacent fabric:4
11. Crease Recovery Angle (Degrees)- Dry and Wet (240)- Minimum

BIS has to say the following about this property:

"The ability of a fabric to retain pressed-in creases and to recover from creasing is an important property, especially in case of apparel fabrics. The need for standardizing a method for evaluating crease recovery of
different fabrics has been increasingly felt with the introduction of crease resistant fabrics. When creasing force is removed from the creased fabric, it tends to recover and the creases in the fabric start diminishing at
varying rates. The magnitude of the crease recovery angle as measured according to this standard is taken as an indication of the ability of a fabric to recover from creasing.

A crease-free rectangular specimen of prescribed dimensions is folded in half so that the two limbs of the strip touch each other face to face, under a specified load and maintained in the state for a specified period.
After the creasing load is removed, the specimen is allowed to recover for a specified time.
is measured. At the end of recovery period the angle of recovery is measured"

12. Drape %: 60-75%
13. Dimensional Stability to dry heat at 105 +-2 deg C in %, Warp:1%, Weft:1%--> maximum.
In this method a sample of fabric is heated by contact with a plain, hot surface under accurately known conditions and changes in specimen dimensions are measured.

14. Dimensional change on washing percent: Warp:2, Weft:2--> Maximum
16. Pilling resistance ( after 5 hours of test): 4--> Minimum
17. Soil Release Efficiency (percent): 80--> Minimum

BIS has to say the following about this property:

"The soiling of textile fabrics is one of the most difficult problems associated with their use. Cotton and cellulosic fabrics do not pose a severe problem of soiling because of their high moisture regain. Nevertheless, the resin finished cellulosic fabrics and fabrics rich in synthetic fibres pose a severe problem of soiling during their usage. The soiling of fabrics is due to: ( a ) interfacial attraction or Van der Wall forces, ( b ) electrostatic attraction, ( c ) mechanical forces, and ( d ) hydrophobicity of the fibres.

The soil is mainly of two types, namely, dry or particulate soil and oily or greasy soil. The former which includes particles of dust, sand, earth, soot, metallic oxides and carbon with tarry substances may be hydrophilic ( metallic oxides ) or hydrophobic ( carbon ) in nature. The latter includes glycerides, long chain fatty acids and alcohols, lubricating oil, etc, which are mostly hydrophobic.

A specimen of the fabric under test is soiled with synthetic soil, washed under prescribed conditions and dried. Simultaneously, a control specimen and a control washed specimen are taken from the fabric under
test. The soil resistance and soil release efficiency of the fabric is determined using the spectrophotometer."

18. pH value of aqueous extract (Hot Method): 6.0 to 8.0

BIS talks about this property:

"The @H of aqueous extract of the textiles affords a useful index to its processing history. In addition, it is becoming more common to demand that the textile, in its various forms, shall conform to certain limits in respect of its acidity or-alkalinity, often expressed in terms of PH values of aqueous extracts."

Under Hot Method, a flask known as Erlenmeyer flask is washed with distilled or deionized water. One test specimen is taken and added to this 100 ml of distilled or deionized. water.The contents are boiled for one hour under reflux condenser. The contents are cooled to room temperature and pH of aqueous extract is measured.

19. Abrasion Resistance ( 5000 cycles) ( Martindale): 4
20. Limited Flame Spread Index : 2--> Minimum

What is FPT ( Fabric Package/Performance Test) and GPT ( Garment Package/Performance Test)

GPT- Garment Package/Performance Test

This test is done to analyze the performance of a garment after washing by the customer as per the wash care label.

We need three identical garments to perform this test:

1.       One Garment- Dimensional Stability

2.       One Garment – Appearance

3.       One Garment – Seam Slippage and Strength

4.       Button Pull Test- A Mock Patti is needed with about ten buttons attached to it.

Dimensional Stability is observed after washing.

Under appearance, visual observations are made regarding any changes in the fabric after washing. Defects like puckering, pilling, free movement of zipper.

Seam Slippage and Strength Test is done for all the seams present in the garment.

The aim is to find if the finished product is identical to the unfinished product.

Various buyers have their different requirements for GPT.

GPT is done after one wash or after three washes. Generally for Indian domestic suppliers or US buyers, GPT is done after three washes. For European buyers, GPT is done after one wash.

FPT- Fabric Package/Performance Test

Under FPT, about 3 meters fabric is required, the following tests are conducted:

1.       Yarn Count

2.       Construction

3.       GSM

4.       Fiber Composition

5.       Tensile Strength

6.       Tear Strength

7.       Colorfastness to washing at 40 deg.

8.       Colorfastness to rubbing.

9.       Colorfastness to perspiration.

10.   Colorfastness to Water.

11.   Shrinkage.

Here is an FPT from a company. 

Basically it contains the color properties and physical properties of the fabric. 

Textile Testing without instruments

The tests as given below can be used to arrive at a preliminary conclusion. Definitive conclusions must be drawn by the standard test methods.

Difference between carded and combed yarns (Or woollen and worsted yarns) of the same count

Untwist the yarn and note the arrangement in the fibers. In carded yarns, the fibers are spread unevenly across the length. In combed yarn, they will lie parallel to the yarn surface. Similar test can be done to distinguish between woollen and worsted yarns.

Closeness of the Weave

Hold the cloth to the light and look through it. It can be determined to find if the weave is loose or close. It can also give you an idea about the uniformity of yarns.

Also run your thumbnail diagonally across the cloth. Any loose weave will manifest itself in the form of pathway made across the cloth after the thumbnail.

Elasticity

Crumple the fabric and note the behavior when the pressure is removed. The fabric should spring back to its former shape quickly.

Starch

Rub the fabric together, starch will come out in the form of dust. Or tear the fabric, dust will fly.

Strength

Grasp the cloth in both hands about an inch apart and pull steadily.

Drape 

Just spread the fabric over a surface so that it hangs down all around it and note the drape.

Colorfastness to Washing and Rubbing

Simply wash it or rub with a cloth.

Fastness to spotting- Used for Silk

Sprinkle a drop of water with little lime added to it. Allow it to dry then brush off.

Strain Resistance on Seam


Push the warp and weft with the finger nails, if they are pushed easily, the material will fray at seam. Another way to teat is to weave a needle in and out of the double of the material as if making a tuck. the Single cloth is then drawn away from each side of the needle and if a row of holes shows clearly alongside of the needle the material will not bear a strain.

Fastness to Perspiration

To test the change of color, dip it in a little warm vinegar and drying between tissue papers without rinsing.

Burn test methods to detect fiber composition are covered elsewhere in this blog.

Source

Thanks for your attention. Did you find the information you were looking for ? Please leave a comment. Do you need to know more ? Please suggest a topic in the comments. You can also join the Forum for your specific queries.

Textile Testing Videos

Here are some of the videos on Testing of various textile properties. Please click the grey rectangle at the bottom of the video ( on right hand side) to see the total playlist.

In this playlist I have included the following videos:

1. Garment Seam Slippage
2.  Fabric Shrinkage
3. Fabric Yarn Count
4. Fabric Abrasion Resistance
5. Fabric Tensile Strength
6. Fabric Tear Strength
7. Fiber Strength Cotton




Thanks for your attention. Did you find the information you were looking for ? Please leave a comment. Do you need to know more ? Please suggest a topic in the comments. You can also join the Forum for your specific queries.

How to instantly determine reed and picks per inch

When checking the fabrics like cotton sheeting, poplin, cambric, voile, lining and mull, it is often required that the reed and picks per inch are determined quickly. One way is to use the pick glass. However, it is inconvenient and taxing to count each and every thread. The other solution is the use of densimeter or lunometer.

Principle of Densimeter

Moire Pattern

The densimeter is based on the principle that when very fine grids are placed one over the other than particular patterns are observed. In this case there are grating lines etched over the artificial glass. The density of grading lines go on increasing from left to right and is marked. When this grating is placed over the fabric, a point in the grating indicates a particular pattern when the density of grating matched with that of fabric. The position of this particular pattern is observed and the value of density is read from the grating.

Usefulness in Textile Testing

Densimeter can be used in atleast three ways

1. To measure the EPI and PPI of threads in the fabric

This works best when the fabric is grey and white. For dark and knitted fabric, the light source should be beneath the surface of the fabric in order to read patterns.

2. To measure the irregularity in the fabric

Presence of broken pattern of interference lines indicate variation in pick counts, differences in yarn count or color faults.

3. For measuring the shrinkage in the fabric

Instead of measuring the shrinkage in the fabric by marking, it is always better to check the number of threads at various position of the sample before and after the washing. This is particularly useful when shrinkage is checked in the made up garments.

How to use it

1.Place the sample on a flat surface. Put the densimeter above it.

2.Rotate the densimeter until a pattern develops as the lines on the densimeter interact with the lines formed by the threads.

3.Depending on how the densimeter is oriented,  the "Point" of the pattern will be pointing to a number on either the Lines per Inch scale or the Lines per Centimeter scale. The number on the scale indicates the thread or line count.

Source

Thanks for your attention. Did you find the information you were looking for ? Please leave a comment. Do you need to know more ? Please suggest a topic in the comments. You can also join the Forum for your specific queries.

Some Selected Notes on Textiles: Part -5

Flammability Test

This is important for nightwear as they are finer and thinner than regular wear and are more prone to flammability than other fabrics.

In the testing, among other things time required for the flame to travel a certain distance is determined. It is now mandatory to have a flammability test if the fabric GSM is less than 88 grams.


Samples are tested both as submitted and after one cycle of washing and dry cleaning to obviate any instance of flammbility finish that might get washed of after one washing. Also iginition behaviour of the fabric is observed. Normally 5 specimens are tested. If they do not get ignited than 10 specimen are tested.

Butane gas of specified parameter is used. Based on the ignition behaviour, fabric is classified into Class I, class II and Class III. You can learn about the classification here.

You can read some facts about fabric flammability here.


Now that you've finished reading this post, what are you going to do? You should join the Forum.

Some Selected Notes on Textiles- Part 4

- Colorfastness to Light: In this the samples is exposed to a light source along with blue wool sample. The fading is observed and the rating is given.  The main difference between American and European Standards is that American standard is time bound. In European standards it is not a time bound test but fading bound test- means you have to keep on exposing the sample till the sample fades to that of blue scale. Factors affecting lightfastness are the type of dyes used, depth of shade, surface structure and finishing chemicals. 

- A cotton pigment printed fabric cannot be dry cleaned . In dry cleaning solvent called Perc- Perchloro Ethylene or Tetrachloroethylene. Pigments are very susceptible to dry cleaning- they will come out. Perc is the only solvent that do not blast. In exports they use MTO . The problem with perc is that it damages Ozone layer. Perc will take out the pigments from the print. However, if you dry clean with MTO, nothing will happen.  Perc does not smell as much as MTO does.  To test for dry cleaing, a bag is prepared where instead of steel balls, stainless steel discs are added. 

- To remove smell from pigment printed fabric, it has to be cured well. To do it, maintain a temperature of 150 deg and allow the fabric for 10 minutes. It will cause phosphoric acid to get liberated and pigment get fixed- for that Diammonium phosphate needs to be added – so fixation takes place under acidic condition.  

- When testing for shrinkage, the fabric is conditioned for 24 hours. Then it is subjected to washing process for 45 minutes to 1 hours. Then it is dried and reconditiond before remeasuring.

- When testing for shrinkage, soft water is used. Alum can be used for softening. Just move the alum on the upper surface for a few times. Now decant the upper portion and use the rest of the water for testing. One can also use wetting agent. 

- Drying can be line drying, wet drying, tumble drying or drip drying. 

Now that you've finished reading this post, what are you going to do? You should join the Forum.

Some Selected Notes on Textiles- Part 3

- Color Fastness to Rubbing – There are two types of it, dry and wet. Dry rubbing is important for the materials like sofa covers where a person sits on it. Normally it is done using Croakometer with 10cm track length and 9.8 N force.

- For all colorfastness evaluation it is done either visually or using spectrophotometer. Normally worst rating is given.

- Colorfastness to water – It is done to measure colorfastness to water under intimate contact when getting wet, for example contact of inner wear to outer garments in rain. The sample is wet in distilled water , put between two acrylic sheets and then it is clamped under a force of 4.5 kg and put in incubator at 37 degrees Celsius for  4 hours.

- Colorfastness to Water is not the same as colorfastness to washing.  In measuring colorfastness to water we use distill water, whereas in colorfastness to washing, the detergent is used which makes the pH alkaline. A case is cited where a fabric had excellent colorfastness to washing but poor colorfastness to water. It can be due to the fact that the fabric was dyed with reactive dyes. There was some hydrolyzed dye present, but it had no reactivity and hence it was unable to react with water so there was no bleeding. On the other hand that hydrolyzed dye migrated in case of pressure and water hence had poor colorfastness to water.  Thus rigorous soaping could have solved the problem. Taking the other aspect, a fabric had poor colorfastness to washing but excellent colorfastness to water. It can be due to the fact the dye is probably sensitive to the pH.

- Colorfastness to Perspiration- Test is done similar to Colorfastness to water; the only difference is that a solution is prepared which simulate perspiration and the fabric is dipped in it, rest of the procedure is the same. Two types of solutions are prepared , one simulating alkaline perspiration with a pH of 8.0 and the other simulating acidic perspiration with a pH of 5.5. To prepare this solution Sodium Chloride and Lactic Acid are the main ingredients. The test conditions of 37+- 2 deg Celcius for four hours under a pressure of 5 kg. – Picture Source and Procedure. 

Now that you've finished reading this post, what are you going to do? You should join the Forum.

How to Use Pick Glass

Pick Glass is used to determine the reed and pick in woven fabric. Reed is actually number of ends or number of warp threads per inch and by picks we mean the number of picks or number of weft threads per inch.  The following procedure is based on IS 1963: 1981 method:

Sampling

1. Avoid sampling within 50 mm from the selvedge.
2. Within two metres from either end of a piece or roll.
3. While sampling from design fabrics it is convenient to:
a) Determine the number of units in a weave repeat from a point paper diagram.
b) Count
i) The number of whole repeats
ii) The remaining units, in the distance across which the threads are to be counted.
iii) From the above data so obtained, the number of threads per centimetre or inch
both in warp way or weft way as required can be calculated.

Procedure

1. Keep the test sample on a flat table and smoothen it out.
2. Set the pointer of the counting glass at zero.
3. Place the counting glass on the fabrics in a direction parallel to warp if weft density is to
be determined and parallel to weft if warp density is to be determined.
4. Find the number of warp or weft threads in a specified length as required.
5. Following the procedure prescribed in steps 1 to 4, determine the number of warp and
weft threads per centimetre or inch in at least four more places.
6. Calculate the number of warp or weft threads per centimetre or inch by the following
formula: n = N ÷ L
Where
n = number of warp or weft threads per centimetre (or inch),
N = observed number of threads in the distance L, and
L = distance in centimetre (or inch) across which the threads are counted.

7. Calculate the mean of all the values and report it as the number of warp or weft threads
per centimetre or inch of the fabric.

Note: Avoid counting same set of warp or weft threads more than once. The value should be
rounded off to first decimal place in case when the results are reported for threads per cm.

An excellent tutorial on how to analyse a fabric using pick glass is found here.

Now that you've finished reading this post, what are you going do? You should go join the Forum.

Textile Testing for a Home Linen Product

Textile Testing is not something that is to be done on a finished product alone. There is a need to measure the effectiveness of each process so that necessary corrections can be done if needed. As an example, for a home linen fabric, the following testing procedures need to be carried out after every process.

Process of Manufacturing a Home-Linen Product

A typical home linen product is manufactured by the following process

Grey Fabric à Singeing and Desizing à Continuous Bleaching à Chainless Mercerisation à Continuous Dyeing range including Pad Dry and Pad Steam à Auto Jiggers with 20 cylinder drying range and open Stenterà Flat Bed Printingà Rotary Printing machine including loop stenter and polymeriser à stenterà Compressive Shrinkageà Calendering à Stitchingà Folding & Packing and Dispatch

The Following Testing procedures are needed at each stage of the process:

1.       Grey inspection and checking

Every supply of grey cloth needs a thorough check for quality of the material. The following checks need to be made

• Checking of damage made during the transit

• Checking of quantity supplied

• Checking of count, reed and pick

• Checking of GSM of the cloth

• Checking of width of the grey

• Checking of knots in every meter of grey

• Checking of any deformity of construction of grey

• Checking of any unusual cuts in the cloth

2.       Singeing and Scouring

After passing through the Singeing and Scouring process, the fabric undergoes the pilling test to determine the pilling and fuzzing characteristics of the fabric. Thereafter another test is conducted to determine the abrasion and pilling resistance of the fabric. If thesample fails this test as per specifications provided by the buyer then the grey cloth is sent back for Singeing.

3.       Desizing

De-sizing is the next step after which the TEGAWA test is conducted in a lab to check the presence of starch and other substances in the grey cloth and in the event the material fails this test then it is required to undergo the process of De-sizing.

4.       Bleaching

The absorbency test, whiteness test and ph testing are carried out in the lab after completion of the processes of bleaching, washing and drying.

5.       Mercerisation

Subsequent to the Mercerizing process the fabric undergoes ph testing and TWEDDEL and Barium tests to check the concentration of caustic in the fabric. The operation is repeated in case the fabric fails the tests.

6.       Dyeing

Post completion of the dyeing process, a number of tests are carried out to test the colour matching of the sample as per the buyer’s demand and colour fasteness of the cloth. The dyeing process has to be repeated in the event the fabric fails these tests.

7.       Printing

After completion of printing on the fabric, the tests relating to colour matching and fastness are carried out once again.

8.       Stenting

Once the Stenting process is completed, lab tests are conducted for carrying out the shrinkage tests, tensile strengths and tear strengths of the fabric.

Now that you've finished reading this post, what are you going do? You should go join the Forum.

The Measures of Fiber Length

The Measures of Fiber Length

1. Mean Length: Numerical Average length of fibres of given population of fibre.

2. Upper Quartile: Length for which 75% of all observed values are lower or 25% higher by weight or number

3. Modal Length: The most frequently occuring length of fiber.

4. Median Length: Length Below and above which 50% of fibres lie.

5. Half Fall Value: The fiber length higher than modal length having half the modal frequency by wt. (Group length longer than mode with frequency equal to 1/2 of mode.)

6. Effective Length: Upper quartile of numerical length distribution from which some of the shortest fibers, having length less than half of effective length are cutailed or eliminated.

7. short fiber %: It is the % of fibers having length less than 1/2 of the effective length value.

8. Uniformity Ratio: Ratio of 50% span length to 2.5 % span length.

9. Span Length: It is the distance that can be spanned by specified percentage of fibers in a test beard.

10. Irregularity: Percentage by weight fo fibers in a sample which are shorter than 3/4th of the mode.

11. Dispersion %: inter quartile range expressed as % of effective length.

How to Determine the Color Fastness of Textile material to Dry Cleaning

How to Determine the Color Fastness of Textile material to Dry Cleaning

Technical Specifications:

Apparatus:

1.To determine colorfastness to drycleaning a suitable mechanical device consisting of water bath containing a rotatable shaft which supports, radially, glass or stainless steel containers ( 75+-5mm diameter x 125+-10mm high) of approximately 550+-50 ml. capacity, being 45+-10mm high from the centre of the shaft should be used. The Shaft/container assembly is rotated at a speed of 40+-2 rev per minutes.The temperature of the water bath is thermostatically controlled to maintain the test solvent at 30 deg +-2 celcius.

2. Stainless stell disc of 30+-2mm x 3+-0.5mm, smooth and free from rough edges of mass 20+-2 gm.

3. Undyed cotton twill cloth of unit area 270+-70 gsm, free from finishing and cut into samples of size 12 cm x 12 cm

4. Grey scale for evaluating change in color and staining.

5. Glass tubes of diameter 25 mm

Preparation of the Specimen

For a fabric sample, take a specimen of size 10cm x 4cm from the sample representing the lot.

If the material to be tested is sewing thread, make a wick of parallel length 10 cm long and about 0.5 cm in diameter, tied near both ends.


Procedure

Prepare a bag with inside dimension of 10cm x 10 cm using the undyed cotton twill cloth by sewing together two squares of this cloth around three sides.

Place the specimen and 12 stell discs inside the bag and close the bag.

Place the bag in the container and add 200 ml of Perchloroethylene or any other suitable solvent at 30 +- 2 deg C

Fix the container in the mechanical device maintained at 30+-2 deg C and run the machine for 30 minutes.

Remove the bag from the container, withdraw the specimen and dry the specimen in air at a temperature not exceeding 60+-5 deg C.

Evaluate the change in color of the tested test specimen with grey scale, after attaining normal moisture content.

Filter the solvent remaining in the container through filter paper and compare the color of the filtered solvent with that of unused solvent in the glass tube placed in from the white card using transmitted light by means of grey scale for assessing staining.

In case of doubt in the color fastness rating as assessed by an observer, the assessment should be done by at least three observers and the overall average rating should be reported.

Report

Report the numerical rating for change in color of the test specimen and the numerical rating for staining of the solvent. Also report the solvent used for the test.

How to Perform Test for Color Fastness to Rubbing

How to Perform Test for Color Fastness to Rubbing

Select a sample that is a representative of the lot.

Technical Specifications:

Apparatus: For determining the color fastness to rubbing a suitable device ( crock meter) with a rubbing finger, comprising a cylinder of 1.6 cm diameter moving to and from in a straight line along a 10.0 cm track on the specimen with a downward force of 9N should be used.

Rubbing Cotton Cloth: Desized, bleached - without finish and cut into 5cm x 5cm squares, should be used.

Grey Scale- Used to evaluate the stain on the cotton cloth

Preparation of the Specimen

1. If the textile to be tested is a fabric, two pieces, each not less than 14 cm x 5 cm for dry rubbing and two pieces for wet rubbing should be drawn from the sample.

2. One specimen of each pair should have the direction parallel to the yarn yarns and other parallel to the weft or filling yarn.

3. If the textile to be tested is yarn or thread, same should be knitted or woven into fabric to provide 4 specimens each of minimum size of 14 cm x 5 cm, two for dry rubbing and two for wet rubbing. Alternatively 4 specimens should be prepared by forming a layer of parallel strand by wrapping it lengthwise on a rectangular card board of suitable dimension.

4. The test specimen should be fixed on the rubbing device by means of clamps such that the long direction of the specimen follows track of the device.

5.In case of multicoloured textiles, care should be taken to position the specimen in such a way that all colors of the design are rubbed in the test. If the areas of colors are sufficiently large, more test specimens should be taken and individual colours should be assessed separately.

Dry Rubbing

With the dry rubbing cloth flat in place over the end of the finger of the crock meter, same shouldl be rubbed 10 times to and fro in a straight line along a track 10 cm long on the dry specimen in 10 seconds and with a downward force of 9 N.

Wet Rubbing

The above described procedure should be repeated with a fresh dry specimen and with wet rubbing cloth. The wet rubbing cloth should be prepared by soaking a fresh rubbing cloth in distilled water and squeezing the same to contain its own weight of water.

The staining of the rubbing cotton cloth should be assessed with the help of a grey scale.

It is necessary to eliminate dyed fibres pulled out during rubbing and retained on the surface of rubbing cotton cloth, the coloration due to staining by dye stuff only should be considered.

In case of doubt on the assessment of color fastness rating by a single observer, the assessment should be done by at least three observers and overall average rating should be reported.

Report

The numerical rating for dry staining and for wet staining of the rubbing cotton cloth for each direction of manufacture should be reported.

How to determine Seam Strength

Seam strength is the strength of seam assembly in a garment. It is a function of the strength of the thread used for the seam, type of seam assembly in a garment and type of fabric used, among other factors.

Failure of seam assembly can occur either by breaking of sewing thread, tearing of the fabric at the seam, excessive yarn slippage adjacent to the stitches or a combination of the above mentioned conditions.

How to determine seam strength in laboratory

In a lab CRE type tensile testing machines such as INSTRON is used. Before testing the samples are prepared.The method is called Grab Test


If the specimens are from manufactured items such as garment then five speicmens are cut having a length of 270 mm on either side of the stitch line and a width of 100 mm parallel to the stitch line.

If the specimens are prepared from fabric then seam strength is measured in warp, weft and bias directions. In such cases swatches are cut in these three directions.

Also two such swatches from two different rolls are joined by the seam assembly- for which we want to test the strength- to measure the parameters.

Before testing the material is conditioned to standard temperature.

The specimen is mounted on the tensile tester. It is operated until the sewn seam or fabric ruptures. The observation is made whether the rupture is caused by Fabric yarn rupture, sewing thread rupture, sewn seam yarn slippage or a combination of two or more of the foregoing. This will give the seam strength.

Repeat this Grab Test for the fabric specimens from which seam failure test is carried out. The result will give the base fabric strength.

Seam strength ( for each direction) will be calculated by the formula:

Seam strength ( gms/cm)= ( Individual specimen seam breaking force in gms)/ Width of specimen in Jaws i.e. 2.5 cm.

Base fabric breaking strength of the individual specimens are calculated by the formula:

Base fabric strength (gms/cm)= (Base Fabric breaking force in gms of individual test specimen)/ Width of specimen in jaws i.e. 2.5 cm

Seam Efficiency= Seam Strength ( Seamed Fabric Strength) x 100)/ Base Fabric Strength

If this seam efficiency ratio falls below 80%, the fabric has been excessively damaged by the sewing operation.

Flex Abrasion Resistance- Determination

Method for determination of Flex abrasion resistance:

1. Cut five test specimens each 200mm. long and of 32 or 38mm width depending upon wheter the number of yarns/dm of the specimen is below or above 200. Ravel the specimen to 25 mm in width by removing from each side approximately the same number of yarns. Do not take two specimens fro the weft test from the same warp ends or any two specimens fro the weft test from the same picks. Take weft specimens at wide intervals.

2 After positioning the bar by means of the yoke holder, place the specimen between the pressure (upper) plate and the reciprocating (lower) plate of the apparatus and locate centrally. with the specified folding bar or folding blade inserted, after being clamped and loaded by removal of yoke holder, distribute the tension exerted by the bar or blade uniformly over the width of the specimen and align the long dimension both above and below the bar parallel to the direction of the reciprocating motion. Position the specimen with the fold at the centre of the upper plate, and the reciprocating plate at the rear of its stroke when the specimen is clamped.

3. Load the pressure plate and the folding bar or blade as required by the material specifications. In the absence of the material specification, the bar load sufficient to produce rupture in excess of at least 100 cycles and preferably in 300 cycles should be used, in combination with the lowest head load (pressure) sufficient to prevent vibration of the upper plate at the start of the test.

The ratio of the bar to head loads shall be 4:1

4. Check the bar alignment after the first 25 cycles. If shifting of bar from its normal position is noticed, discard the specimen and make the proper adjustment.

5. Remove the pills of matted fibres debris interfering with proper contact between the specimen and the folding bar or folding blade during the test if they cause a marked vibration of the pressure plate or otherwise interfere with proper abrasion. The pill should be removed by careful clipping. Do not correct the vibration of the pressure plate due to pilling by applying additional load. Check the position of the specimen after additional cycles to ensure that the removal of the pills has not altered the bar alignment.

6. If the specimen slips in the clamps or tension and pressure upon the folded specimen do not remain constant during the test, or an anomalous wear pattern is obtained, discard such individual measurements and test an additional specimen.

7. Before every test the blade is rinsed with degreasing agent.

8. The end point is determined by abrading the specimen until rupture and number of cycles is recorded.

9. The report should include the following information:

a. Abradent used, bar or blade
b. Average number of cycles required to produce rupture the specimen

Total No of cycles Report to the nearest cycle
Below 200 10
200 to 299 25
1000 to 4999 50
5000 and above 100

c. Tension and pressure used.

Determination of Abrasion Resistance of Fabric

Determination of Abrasion Resistance of Fabrics

Plain Abrasion Resistance

Apparatus - Universal Wear Tester

Prior to test, the fabric should be Conditioned to moisture equilibrium from the dry side, in the standard atmosphere of 65+-2% relative humidity and 27+-2 deg C temperature. The test should be carried under standard atmospheric conditions.

Method for determination of plane Abrasion Resistance

1. Cut five circular test specimens of 112 mm in diameter, taking care to take specimens from areas containin the same wales or courses in knitted fabric or the same warp or weft yarn in woven fabric.

2. Set the instrument for inflated diaphram test.

3. Place the specimen over the rubber diaphram in smooth condition and clamp the specimen in place without disturbing it.

4. Place the abrasive paper on the abradent plate under sufficient tension to be held smooth and in such a position that the contact pin, reaching through a hole in the abradent is even with the surface of the abradent. In the absence of any specific material specification , zero emery polishing paper should be used as the abradent.

5. Set the air pressure under the diaphram and load on the abradent plate. In the absence of any specific material specifications, the air pressure should be 0.3kg/sq.cm (4 p.s.i.) and the load on the abradent should be 454 gm. Ensure that the air pressure control and contact between the inflated specimen and loaded abradent is in a state of equilibrium before abrasion is started. To ensure consistent inflation of the diaphragm, inflate to a higher air pressure ( 25 per cent) and then reduce the testing pressure.

6. If the unidirectional abrasion is desired, disengage the rotation mechanism of the specimen clamp and bring the specimen into the direction by turning and setting the clamp after the diaphragm has been inflated.

7. In the event that multi-directional abrasion is required, or if no specific indication as to the abrasion direction is given in the fabric specification, engage rotation mechanism of the specimen clamp.

8. Remove pills of matted fibres interfering with proper contact between specimen and abradent during the test if they cause a marked vibration of the abradent plate.

9. If the specimen slips in the clamp or the air pressure does not remain constant during the test or anomalous wear pattern is obtained, discard such individual measurements and test an additional specimen..

10. One of the following methods is selected for determination of end point as per test specifications:

a. Breakage of Thread: Abrade the specimen until all fibres in the centre of the abraded area are worn off so that the diaphragm and abradent head come into contact and the instrument automatically stops.

b. Removing a predetermined thickness of the material. Abrade the specimen using the electrical depth micrometer to determine the automatic end-point for removing a predetermined thickness of the material from the specimen.

11. Unless the continuous changing abrasion head is used, abradent paper is changed after every 300 cycles.

12. Report shall include the following information :

a. Type of abradent
b. Type of abrasion ( unidirectional or multi directional)
c. No. of cycles to reach the end point as determined by electrical contact.

Related Links

Testing Abrasion Resistance For Socks

Chemical Solubility Test for fiber identification

Please see here for Chemical solubility test for fiber idenfication.