What are the reasons for the defects of woven fabrics in the finishing after printing and dyeing(1)?

(1) Oil drop-shaped stains

Appearance: Occurs mostly on E/R blended fabrics, with oil drop-like spots after dyeing, slightly darker than normal parts. Observing with a magnifying glass, the plush in the dark-colored part of the fabric has a tiny bead shape at the tip, and the plush is more than the normal part.

Cause: This is due to the uneven singeing, the dyed spot with thick color, the plush is not fully burned off, and becomes a fusion group at the tip, which has strong color absorption, so the dyeing is thicker.

(2) Poor penetration spots

Appearance: After dyeing, the surface of the cloth is colored cloud-like in shades of light.

Causes: 1). Desizing and refined pulp are not sufficient, or wax and other substances removed after treatment are attached to the fabric. 2). When bath dyeing, the bath ratio is too small and the heating rate is too fast, so that the dyeing solution is gelatinized.

(3) Bleached Hole

Appearance: The embryonic cloth is normal. After bleaching with hydrogen oxide, the warp or weft yarns on the cloth surface are broken, forming small holes.

Cause: There is rust on the cloth surface, or the bleaching bath water contains iron ions. During the bleaching process of the cloth, it is rapidly oxidized with hydrogen peroxide and the yarn is broken.

(4)Skilteriness

Appearance: The cloth surface has irregular flake color shades.

Cause: Desizing and scouring of the pre-treatment project were not completely done.

(5) Mist

Appearance: Flake-like stained spots, deep or shallow, with inconspicuous outlines, different shapes and sizes, not concentrated in locations, and no definite rules.

Causes: 1). The fabric to be dyed is splashed with sewage or other medicines. 2). If it is not dried immediately after scouring and bleaching, it will accumulate on the cloth cart for a long time, and some fabrics will have air-drying watermarks. 3). The embryo cloth is stained with oil, and the traces left after brushing with strong detergent during embryo inspection.

(6) Color difference

Appearance: Dyed or printed fabrics, the color of the finished product dyed, or the color of the printed pattern is not exactly the same as that specified.

Causes: 1). The sample used for the specified color sample is too small, and the exact color matching cannot be achieved after proofing. 2). When preparing dyeing liquid or printing paste, weighing dyes and auxiliaries is not accurate enough. 3). The process and the conditions of the proofing are not fully matched, and no empirical correction has been made.

(7) Color difference between cylinders

Appearance: Large batches of fabrics, dyed in fractional vats or several times in one vat, if not dyed in the same vat, there are differences in shades of light.

Cause: Although the cylinders are of the same type, their functions are slightly different. In the dyeing process, the conditions of each operation cannot be the same.

(8) Yin and Yang colors

Appearance: dyed full-width fabric, there is a color difference between the front and back sides.

Causes: 1). The dyeing roller leaves the edge of the cloth, and the direction of the cloth is not in the same plane as the pressure suction line. 2). The heat on both sides of the fabric is different during pre-drying after pressing. 3). The wind speed on both sides of the fabric during resin processing is different.

(9) left and right color difference

Appearance: Full-width fabric, the color gradually becomes darker or lighter from the left selvage to the right selvage. Fold and contrast the two fabric edges, and there is a significant difference in color.

Reasons: 1). The pressure suction rate of the rollers of the dyeing machine gradually increases or decreases from left to right. 2). Improper engraving or poor production of printing rollers or rollers. 3). The pressure on the left and right of the printing roller roller or steel roller varies. 4). During pre-drying, color fixing or resin processing, the temperature or wind speed in the left and right sides of the box is not the same.

(10) Medium dilute, medium concentration (Listing)

Appearance: The color of the fabric near the edge and near the center varies in shades.

Causes: 1). In the open-width cross-winding dyeing machine, the curvature of the spreading device is not suitable, so that the rate of dye liquor absorption by the cloth is inconsistent. The temperature in the dye bath is inconsistent with the center at both ends. Add new staining solution unevenly. 2). In the liquid dyeing machine, the circulation speed of the fabric is slower, and the heating rate is faster. 3). In the open-width continuous dyeing machine, the suction rate between the center and both ends of the roll is inconsistent. During drying, the temperature and wind speed are not uniform at both ends and the center. In the continuous dyeing process, the tension on the cloth body is not uniform. 4). The center and both sides of the fabric formed during the pretreatment process are inconsistent. 5) When printing with Roller or Rodali, the pressure applied is inconsistent between the center and both ends. 6). The resin is not processed immediately after dyeing, or the resin is not completely dried after being applied, and it accumulates for a long time.

(11) Tailing of Ending

Appearance: A group of several or dozens of fabrics, after continuous dyeing under the same set conditions, the beginning and the end of the dyed fabrics, there are shades of difference in color.

Causes: 1). In the pretreatment process, there are differences in desizing, scouring, bleaching, mercerizing, and shaping before and after a batch of fabrics occurs. 2). In the open-width cross-roll dyeing, the dyeing rate of the combination of dyes used is inconsistent, the method of guiding the cloth and the roll is not appropriate, the dye is added incorrectly, and the dyeing temperature is not properly controlled, all of which will cause the color difference between the beginning and the end. 3). During continuous dyeing, the pressure suction rate changes, the stability of the dyeing solution is not good, and the temperature during drying changes gradually. 4). If the compatibility between the dye and the auxiliary used in combination is poor, an uneven layer of dye particles and water will occur. Due to capillary action, water first enters the fiber, resulting in a change in the concentration of the dye solution, resulting in a color difference between the beginning and the end. 5). When dyeing with ice dye, the dye will gradually hydrolyze during the long-term soaking process, which will also cause the color difference between the beginning and the end.