Identification of fabric defects is a core and important link in the entire fabric quality production process. Generally fabric fault or defect is any abnormality in the fabric that hinders its acceptability by the consumer. Fabric is produced with interlacement of warp and weft yarn or loop formation of yarn. Different types of fabric defects that can occur during the manufacturing process. Some fabric defects are visible and some defects are invisible. But it is of great importance to use accurate and efficient detection methods to improve the detection and identification of fabric defects. In this article I will discuss on visible faults of fabric with appropriate pictures.
Fabric defects / faults may be result from the following reasons. They are:
- Defects resulting from faulty yarn
- Faulty weaving process
- Incorrect dyeing and finishing processes
These defects have a visible effect on a fabric, comprising all the disproportions within the structure of the textile material that interfere with its end use. If these faults are not detected early, that is, during the fabric manufacturing process, they can drastically affect the production process and the quality of the finished product. According to the BS 6395: 1983 standard, a fabric fault is defined as any feature within the usable width of a fabric that will downgrade the resultant garment.
Visual faults can be categorized as spinning, weaving, dyeing, and processing faults, as well as mending faults, which arise due to mistakes during the fault removal or mending process.
Here I will discuss some essential defects or faults that are appear in woven fabric.
1. Warp direction faults:
Material defects in the warp direction occur in the threads and are defined as follows:
a. Thick or thin end: A warp thread that differs in diameter from the surrounding normal ends.
b. Coarse end: Coarse end is a warp yarn that has a diameter too large, too irregular or that contains too much foreign material to make an even, smooth fabric.
c. Tight or slack end: A warp thread, or part of a warp thread, that is tighter or slacker than the surrounding normal ends.
d. Missing or broken end: The absence of a complete warp thread or part of a warp thread.
e. Broken pattern: Broken pattern is caused if warp yarn is broken when a pattern was being created during weaving.
f. Double end: A thread, or part of a thread, in the warp, which has accidentally been doubled.
g. Defective selvage: Selvage having warp yarn under high tension may cause pucker or wavy surface resulting in defective selvage. Besides, selvage may be thick and thin and may possess broken ends, temple mark, etc. Defective selvage may make the whole fabric defective and fabric finishing difficult. More tension on selvedge yarns, late shedding, improper cutting at selvedge by cutter and improper selection of selvedge weave for the fabric being woven are the main reasons for bad selvedge.
h. Warp streaks: Streak running in warp direction. Group of yarns having different dye shades may result in warp streak. Warp streaks are narrow, barre and dense stripes running along the warp direction.
Testing for faults in the warp direction is conducted using a simple visual assessment of the imperfections in the fabric to decide which would be unacceptable in a garment. The number or faults in the fabric are then counted and their lengths are measured. Faults are tolerated if the residual cloth width satisfies the terms of the contract.
2. Weft direction faults:
Material defects in the weft direction also occur in the threads and are defined as follows:
a. Thick or thin pick: A weft thread that differs in diameter from the corresponding normal picks.
b. Coarse pick: Coarse pick is a filling yarn that is too large and imperfect to appear to advantage in the final cloth.
c. Tight or slack pick: A weft thread, or part of a weft thread, that is tighter or slacker than the corresponding normal picks.
d. Loose weft or Slough off or Snarl: When a bunch of or coil of yarn slips from the pirn during weaving then thick yarn bunches or coils appear on the fabric. Proper monitoring of strength and chase in pirn winding can solve this problem.
e. Missing pick: Mis pick is a defect in woven fabric caused by a missing or out-of-sequence weft yarn. The unintentional omission of one complete pick across the full width of the cloth.
f. Broken pick: A pick that is inserted for only part of the cloth width. A filling yarn that is broken in the weaving of a fabric appears as a defect. Improper functioning of weft stop motion results in broken picks undetected and going in to the fabric.
g. Double pick: The thread or pieces of thread in the weft which form the woven structure but are accidentally doubled.
h. Trailer: Weft yarn that has been pulled inadvertently into the fabric during weaving.
As with the assessment of faults in the warp direction, testing for faults in the weft direction is also conducted using a simple visual assessment of the imperfections in the fabric that would be deemed unacceptable in a garment, followed by a measurement of their lengths. In this case however, no tolerance is permitted for faults detected using this method of control.
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3. Stripes in the warp:
Stripes in the warp, which extend either for part of the warp direction or over its entire length and which show up as faults against the rest of the material, are considered being faults in the fabric. A visual assessment of the fabric and the measurement of the length of the stripes are sufficient tests to decide whether the imperfections would be unacceptable in a garment. Stripe faults are tolerated if the residual cloth width meets the terms of the contract.
4. Bars in the weft:
Bars in the weft are defined as streaks, which occur over either the full or part of the length of the weft direction and which show up against the rest of the piece. Again, a visual assessment of the imperfections is used to decide whether they would be unacceptable in a garment. The length of the bars is also measured if they occur in a sequence. No tolerance is permitted for faults detected using this method of control. The normal reasons are the periodic medium to long term irregularity in the weft yarn, count difference in weft, excessive tension in the weft feed package, especially in filaments, variability in pick density and difference in twist, color or shade of adjacent group of picks, difference in blend composition or in the cottons used.
5. Knot or slubs in the warp or weft threads:
Knot or slubs in some of the weft or warp threads are considered to be faults when they are visible to an experienced person and when they spoil the appearance of the fabric. This visual assessment is sufficient to test whether the faults would be unacceptable in a garment and no tolerance is permitted for faults detected using this method of control.
6. Mixed warp and weft:
If wrong yarn is used instead of correct one, this defect appears.
7. Smashes:
Daggers not working, frog spring ineffective, bad shuttle, improper boxing of shuttle, worn out picker, worn out transfer hammer, damaged pirn and entanglements are main causes of smashes.
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8. Faulty mending and burling, tears, holes and stains:
Faults caused by mending and burling, tears, holes and stains are defined as follows:
a. Faulty mending: poor appearance of repair on the surface of the fabric.
b. Faulty burling: The presence of faults which have not been removed during burling.
c. Tears, cuts and holes: Various forms of cloth breakage.
d. Stains: Areas of the cloth that have been contaminated with impurities.
e. Iron Mark: Sometimes iron marks appear in the fabric caused from rusted reed.
These types of faults are again tested using a visual assessment of the imperfections and the measurement of their length to ascertain whether they are unacceptable for use in a garment. No tolerance of these faults is permitted.
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9. Fabric pieces cut in several parts:
Fabric is deemed faulty if it is cut across the whole width in two or more parts, the total being equal to the required length. Once it has been verified that the number of the separate parts together makes up the length ordered, no tolerance of this fault is permitted.
10. Reed marks:
Reed marks may appear due to defective reed, improper warp tension denting.
11. Reediness:
These are very fine cracks or lines between groups of warp threads, caused due to excessive warp tension, late shedding, use of coarse reed with more number of ends per dent, bent reed wires, improper spacing of reed wires, wrong drawing and insufficient opening of shed, i.e., tension difference between top and bottom shed lines during beat up.
12. Rough cloth surface:
If fabric is weaving with yarn, under heavy tension or unbalanced tension then rough cloth surface appears. In the weaving time, if un-steamed yarn is used then fabric surface becomes dull.
13. Shade bar:
Shade bar is a distinct shade change of short duration across the width of the fabric. This is normally due to a mix up of weft with different property.
14. Shuttle mark:
Shuttle mark appears along weft yarn and is caused due to friction with the shuttle.
15. Shading:
Shading is a common problem for dyed fabric. When color variation occurs from wrong handling of fabric.
16. Bullet:
Bullets are low twisted double yarn seen weft wise in fabrics. Those are generally zero twisted parallel yarns. Practical causes of faults are improper functioning of bunch motion, incorrect yarn path through spindle, loose tensioners, capsule and spring working, insufficient yarn as bunch and knot is not applied after removing bunch yarn.
17. Mil-dew:
If fabric is kept in wet places in store then mil-dew occurs. This is caused due to fungal invasion.
18. Cracks:
A higher pick density than the normal is referred to as starting mark while a lower pick density is referred to as crack. This kind of defect is mainly caused by the mechanical faults in the loom.
19. Tails out:
If the cutter doesn’t work properly, this fault is appears in woven fabric.
20. Gout or foreign matter:
Gout is a foreign matter like lint, waste, etc. that appears into the woven fabric. The main causes to produce this kind of faults for improper loom cleaning and unclean environment.
21. Temple mark:
In the light woven fabric this kind of defects are appears. When yarns are misshapen from their paths then holes are produced near the selvedges.
22. Float:
Slack warp and faulty pattern card are the main reasons for a float in a woven fabric. Damaged or broken heald wire and foreign matter falling on warp can also cause floats.
23. Neppy:
For the excessive amount of neps in yarn, this kind of defect is found on woven fabric surface.
24. Misdraw / wrong denting:
One or more ends are incorrectly drawn in the reed.
25. Skip stitch:
While stitching on a very high speed using a chain stitch, precise control is required to prevent a skip stitch. Some of the measures given below can be used, although a systematic problem-solving approach should be used to identify the root cause and arrest the problem.
26. Stop mark (starting mark):
Stop marks are narrow band of different weave density across the width of a woven fabric caused by improper warp tension adjustment after a loom stop. A well trained weaver can reduce this type of defects.
27. Low or high SPI:
Low or high SPI can happen due to the wrong speed of either the head or the fabric. General remedies can be attempted; however, we suggest looking for a specific problem and resolving the root cause.
a) If the SPI are regularly high or low, the speed of the head and the speed of fabric should be checked. SPI is a result of:
SPI = (Stitching head RPM)=(Fabric speed in m/min x 39:3)
b) If on a specific portion, the SPI is varying then hindrance in the fabric, malfunction of the head or a worn out belt or belt slippage should be checked for.
28. Less fold in hem:
The fold is made in the hemming machine with the help of folders. If the folder malfunctions in the event of a blockage or folder damage, a shorter fold is made. This may lead to hem opening after repeated washing.
29. Set mark:
Set mark is a defect in woven fabric resulting from prolonged loom stoppage. Because of the humid weather and the fine dust present in the atmosphere, the cloth exposed shall get slightly different color and also some relaxation takes place. A combined effect gives a line in weft direction.
30. Jerk-in:
Jerk in is an extra piece of filling yarn jerked by the shuttle into the fabric along with a regular pick of filling.
Conclusion:
Fabric defects can impact the quality and usability of textile products. Identifying and addressing various fabric defects early can help maintain high standards, reduce waste, and ensure that the end product meets consumer expectations. Effective quality control methods are key to minimizing defects and improving the overall quality of textile products.
References:
- Handbook on Fabric Manufacturing: Grey Fabrics: Preparation, Weaving to Marketing by B. Purushothama
- Design of clothing manufacturing processes by- Jelka Ger š ak
- Quality management in apparel industry by- Engr. A.J.S.M Khaled
- Woven Terry Fabrics: Manufacturing and Quality Management by Jitendra Pratap Singh and Swadesh Verma
- https://www.slideshare.net/azhartip1/fabric-faults-81244352
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
