Denim Fabric Defects Reference Guide

Common denim fabric classification

 denim fabric can be divided into plain weave, twill weave, slub, etc. due to their different production processes, as shown in Figure 1.1. In terms of the ingredients contained in denim fabric, denim is divided into combed and carded, 100% cotton, cotton and linen blended with Lycra, etc. At present, the market is mainly popular ring yarn denim, warp and weft slub denim, overcolor and assorted denim, etc.

Figure 1.1 Types of denim fabric

Traditional denim vs. generalized denim

 Traditional denim is a right twill fabric, which is made of indigo-dyed cotton warp yarns and white weft yarns interlaced three times. The woven yarn is woven with pure cotton natural fiber. The denim fabric has strong moisture absorption, good air permeability and no irritation to human skin. At the same time, indigo is a coordinated color that can match other colors. The thick special warp yarns are interwoven, and the color floats of the warp yarns and the white floats of the weft yarns are matched in proportion to form a cloth with clear blue and clear texture. In addition to the use of pure cotton yarn, denim fabric in a broad sense also use other fibers or synthetic fibers. The dyeing of warp yarns has also got rid of the traditional single indigo dyeing, and a variety of colors have appeared, making denim fabric from a single raw material, thick and single tone. Varieties are developing in a multi-variety and multi-color direction.

 Characteristics of denim clothing

Due to factors such as raw materials, yarn characteristics, weaving methods, etc., the use of different processing techniques will cause denim fabric to have different appearance characteristics. The denim fabric is woven with coarse special yarn, and the finished product is thick and heavy. When tailored as a garment, the garment has a three-dimensional shape, unlike other fabrics, which is soft; at the same time, the denim fabric is wear-resistant, cost-effective, and is loved by consumers.

Common defect types of denim fabric

Denim fabric is a fabric that is woven with warp yarns dyed and sizing with indigo dye. In the production process of denim fabric, defects may occur in any process. The main defects of denim fabric are shown in Table 2.1.

Denim fabric defect types	Defect specific names	Causes and appearance
Raw yarn defects	Thick warp	One warp is thicker than others
	Thick weft	A weft yarn is thicker with faint white streaks
	Uneven yarn	The cloth surface is unevenly wavy, with faintly visible nodular white marks
	White star defects on cloth	The neps and impurities on the weft yarn are woven into the cloth, and the cloth surface shows white star defects
Dying defects	Shade bar	The cloth surface shows traces of different shades of color in the weft direction
	Color difference between head and tail	Color difference between cloth head and cloth tail
	Warp color streak	The fabric has a dark or light streak in the warp direction
Weaving defects	Weft crease	When the loom is turned on, there are continuous streaks in the weft direction on the cloth
	Warp break	One or more warps are missing in the warp direction of the fabric
	Weft missing	Missing a weft in the twill weave
	Disorder warp and weft	The warp and weft yarns on the cloth are in disorder
Finishing defects	Uneven singeing	Uneven singeing, feather-like warp stripes
	Edge color difference	There are obvious differences in color on both sides of the cloth edge

Table 2.1 main defects of denim fabric

Table 2.1 shows the causes and manifestations of denim fabric defects. Starting from the causes of defects, preventing denim fabric defects will help improve the grade of denim fabric, reduce the cost of later manual inspections, and improve corporate efficiency.

Analysis of defect characteristics of denim fabric

From the previous chapter, we know that in the process of denim fabric production, defects may occur in any production process. Defect detection is an important part of denim fabric production and quality management. At present, manual inspection is easily affected by subjective factors and lacks consistency. At the same time, working under strong light for a long time has a greater impact on workers’ eyesight.

Due to the wide variety of defects and diversified shapes, the denim fabric image data set in this paper uses high-definition denim images collected by the first-line textile workshop. There are 9576 images in total, including 5913 images with defects and 3,663 images without defects. Including defects such as knots, three threads, holes, oil stains, etc., the defect data of denim fabric is manually confirmed by experienced fabric inspectors and manually marked. The image resolution is 2446*1000, the feature details are clear, and the corresponding xml format information is generated file. The data set covers all kinds of important defects in denim fabric, and each image of denim fabric contains one or more defects. Common defects in denim fabric are shown in Figure 2.2 below.

Fig 2.2 Common defects of denim fabric

 

Perform statistical analysis on the denim fabric data set. The statistics of various defects are shown in Table 2.2, and the statistical graph of the denim fabric defects is shown in Figure 2.3.

Defect name	Count (pcs)	Defect name	Count (pcs)	Defect name	Count (pcs)	Defect name	Count (pcs)
Cloth slot	1528	Break warp	243	Weft missing	106	Reed Mark	64
Trash fiber	1037	Pulp spot	234	Dead wrinkle	100	Slippage yarn	63
Thick weft	646	Stains	233	Oily	98	Bad weft	56
Broken spandex	317	Thick warp	213	Slippage star	93	Uneven singeing	50
Hole	305	Slub	174	Repair mark	78	Wavy shading	36
Loose warp	297	Piercing	148	Rubbing crease	74	Color difference shading	26
Piercing	283	Stretched warp	143	Filling floats	69	Double weft	14
Hiding shading	262	Flower springboard	109	Water stain	69	Clouded thick and thin yarn	11

Table2.2 Statistics of denim fabric defects

Testing standards on denim fabric

ASTM D6554 / D6554M – 14 Standard Specification for 100 % Cotton denim fabric

Contact us to get the free Pdf standard.