1、Reasons for the appearance of dyeing defects

1. Reason for grey fabric: Many potential defects in dyed fabric are caused by poor quality of grey fabric, such as weaving defects and yarn defects. Due to the mixing of different batches of yarn, weaving defects such as warp and warp stripes, weft and weft stripes are formed on the fabric. For these problems, if the salesperson knew and understood them before sales, the best way to solve them is to bleach them into bleached fabric.

2. Reason for pre-treatment: Good pre-treatment of fabrics is the foundation for processing high-quality products, and poor pre-treatment can cause many dyeing defects. Uneven surface appearance of the fabric caused by poor singeing. The fuzzy black flowers caused by the flame gap of the singeing machine, especially the light spots, are caused by the melting balls produced by synthetic fibers during singeing. When the singeing machine is not suitable or contaminated, it will produce spots of charcoal or tar like substances, which can cause rough and hard feel due to strong or extreme singeing flames. Uneven desizing can cause anti staining or sizing spots. Condensate droplets from the rusty pins or when the fabric comes into contact with rusty surfaces in the cooking pot can form rust spots. Deep staining spots and oil stains are caused by insufficient cooking of the grey fabric, uneven whiteness, and uneven mercerization. From the previous processing to the next dyeing process, the fabric should be cold, with a pH value connected to neutral and no residual alkali, which can prevent problems such as head and tail color difference, deep or light color, fixation, and uneven coloring.

2、 Common defects in long car dyeing

1) Wrinkles are caused by uneven tension on the rolling mill or significant differences in pressure passing through the rolling points, bending or deformation of the guide roller, wear of the guide roller or drying cylinder bearings, accumulation of dirt on the guide roller or drying cylinder, misalignment of the drying cylinder, and improper temperature of the drying cylinder, all of which can cause wrinkles.

2) The main reasons for the color difference between the left and right edges are uneven rolling point pressure, residual alkaline agents, leather surfactants, and silicon salts in the fabric, varying degrees of roller wear, and improper selection of rollers.

3) Stains are caused by poor modulation of the powder and dye, insufficient filtration, improper temperature modulation, improper storage or stirring of the slurry dye, and improper composition of the dye bath.

4) The main reason for water stains is that the temperature of the interlayer at the top of the steamer is too low, there is condensed water at the inlet of the steamer, and the guide rollers inside the steamer do not rotate.

5) Washable, wear-resistant, and poor light fastness are caused by the deposition of unfixed dyes on the fabric.

6) Light colored spots are caused by excessive accumulation of cotton lint on the guide roller.

7) The reason for color change is that the structure of dye chromophores often changes due to certain external conditions, resulting in certain changes in color light. Common conditions include temperature, humidity, light, and light source.

8) The color difference of the sample size. The reason for this is that there are differences in dyeing processes between large and small samples, such as the use of dyes and chemicals, soaking time, fixation time and temperature, differences in weighing accuracy of different equipment used, differences in pre-treatment semi-finished products, and selection of water. Both will result in differences in size samples, so small samples need to be replicated before finalizing the large-scale production process.