Spots are a single color mixed with various spots or markings such as white, light, dark, dark or black. They come in various shapes and sizes, most of which are irregular and have many causes.
Causes
1. White stains
1) Such as wax spots, pulp spots, etc., water droplets, hard water and sand weaving defects;
2) The blank is not fully soaked before dyeing, causing white spots after dyeing. ;
3) There are calcium spots and alkali spots on cotton fabrics;
4) Calcium hypochlorite is used in the bleaching process , the decomposed lime remains on the fabric and has not been washed, resulting in white spots that resist dyeing after dyeing;
5) The semi-finished product is partially air-dried after mercerization, and the fabric is partially alkali-containing .
2. Light stains
There are dye repellents on the fabric, resulting in semi-repellent, or During the dyeing process, water dripped from the cloth to dilute the dye solution, and the fabric was stained with floral wool;
1) The fabric was not cooked through, and the dye base contained dye-repellent substances;
2) When dyeing rough fabrics, there are water stains on the fabric, and the fabric is rolled into the roll and left for too long, causing shallow water stains;
3) When dispersed blue dye is used, very light shadow stains often appear on the cloth;
4) Reactive dyes are rolled and stacked, and the film is not wrapped enough Tightly, condensed water penetrates into the cloth roll and causes light stains;
5) Direct dye dyeing is not fixed and encounters water droplets, causing light stains.
3. Dark stains
The cause depends on whether the fabric is desized before dyeing. , are closely related to alkali conditions, dyeing material operation, foaming conditions in the dye liquor, whether there are colored cilia on the drying cylinder, the execution of the dyeing process, and whether impurities such as heavy metal salts are contained on the fabric and in the dye liquor.
1) There are starch stains on the fabric, which turn into dark stains after dyeing;
2) Indistin The fabric on the foam in the color developing liquid shows cloud-like stains;
3) After dyeing the polyester-cotton blended fabric, it is dried in a drying drum. The drying drum is stained with colored cilia, and after hot melting Appearing as dark stains;
4) The poor dissolution of the phenol color base was brought to the fabric and became irregular dark stains after pad dyeing. In addition, the rollers had scars. It will also occur if it is not easy to roll dry;
5) The temperature and pH value of the ice dye developing solution are relatively high, forming tar-like scum;
6) The naphthol primer dries too quickly and can easily cause dark spots;
7) The effects of calcium, magnesium, zinc, aluminum and other metal ions on diazonium salts Impact;
8) The fabric is in long-term contact with copper during the scouring and bleaching process and during the phenol priming process;
9 ) Neutral dyes are dissolved in hot water and are easy to condense and adhere to the fabric;
10) When dyeing with sulfur dyes, the semi-finished products may be unevenly desized, dirty, or have stains. Red spots will occur after local air-drying alkali spot dyeing;
11) During use, the cylinder of the cylinder singeing machine will gradually produce an oxide film, which will affect the quality of the singeing.
4. Rust spots: related to rust
1) There is rust on the cloth before bleaching. Not removed by pre-treatment;
2) Contact with iron during dyeing and finishing;
3) Direct dye jig dyeing Sometimes, the salt contains too much impurities, which corrodes the ironware and causes rust;
4) The water used in processing contains rust.
5. Spots
Mainly occur during cooking, uneven cooking, resulting in Poor circulation, in addition, insufficient materials, too short time, dirty desizing before scouring, too low temperature during scouring, etc.
6. Alkali spots
Mainly occur in the scouring process. The scouring liquid contains a lot of impurities, the pot cover is not laid properly, the circulation of the scouring liquid is poor, and the residual liquid is not drained cleanly through the cooking cloth, causing local air-drying and causing alkali-containing impurities to stick to the fabric. After scouring and steaming, it cannot be washed with water. , insufficient moisturizing and heat preservation during desizing, causing air-drying, or failure to dry in time after mercerization, resulting in air-drying.
7. Calcium plaque
Related to the presence of calcium ions, hard water is used for scouring, and when bleaching , the residual calcium in the fabric has not been removed.
8. Mildew
There is slurry on the fabric, which is easy to cause under certain temperature and humidity. Mildew spots form.
Overcoming methods
Dyeing finished products show white stains, light or dark stains
1. There should be no wax spots on the dyed base;
2. Semi-finished product desizing requirements Clean;
3. Pay attention to the quality of dyeing water;
4. Prevent water droplets from dripping on the dyed base or during the dyeing process;
5. The following methods can be used to prevent and remove rust stains:
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1) Adding sodium silicate to the scouring liquid can stabilize the iron contained in the scouring water;
2) You can apply baking ethylene oxide resin on the guide roller and cloth roller to prevent rust;
3) If you find rust spots on the fabric, wash them off with warm oxalic acid, and then use Wash with clean water, otherwise the fiber will be brittle and damaged;
6. Measures and methods to prevent spots, alkali spots, calcium spots and mildew spots
1) Raw spots: Cook evenly, if not, cook again;
2) Alkali spots: Pot surface cover The cloth must be spread out to prevent the cloth from floating out of the liquid. The residual liquid must be washed in time to prevent the cloth on the walls of the cloth pot from being heated and baked. The alkali on the cloth will concentrate and turn into uneven stains. After discovery, It can be washed away with dilute hot hydrochloric acid;
3) Calcium spots: The scouring water must be softened before use. The scouring liquid must first add a water softener, and then add soap, etc., such as dyeing Calcium plaques are found before and can be usedWashing with dilute hot hydrochloric acid;
4) Mildew:
7. Strictly control the The quantity of products, try your best to avoid stains during transportation;
8. Pay attention to the mixing operation to ensure that the dye is fully dissolved;
9. During dyeing, the process must be ensured;
10. Pay attention to the influence of foam during the process;
11. Try to eliminate the interference of heavy metal ions;
12. Clean the equipment.
Identification of stains
1. Characteristics of mold spots: different shapes, dotted and They are lumpy in color, ranging from yellow, green, and black. The lighter ones can be removed by cooking, while the severe ones are difficult to remove and damage the fibers. You can smell varying degrees of musty smell before the formation of mildew. It is especially easy to produce mildew during the yellow mold season, and the mildew is continuous and large in number.
2. Stains seen on semi-finished blanks and dyed finished products: stains on fabrics, some of which are found on semi-finished blanks It can be seen on the surface, such as: stains, rust spots, calcium spots, mildew spots, raw spots (vaguely visible), alkali spots (after air-drying), but some stains are difficult to find even if they already exist before dyeing, such as wax spots. , pulp spots.
3. Characteristics of water-repellent stains: As long as the quick hair method is used to identify them, water cannot wet the stains, and there are many water-repellent stains. It is the formation of wax spots and raw spots.
4. Identification of wax spots and raw spots
1) Different colors: wax spots It has a strong anti-staining effect, and the stains appear white after dyeing. The spots are not as strong as wax spots, and the stains after dyeing are lighter in color;
2) Different shapes: wax The shape of spots is generally small, and the shape of the defects is related to the waxing operation. Generally, it is not dyed in the warp direction, but it is dyed in the weft direction or has slight dye repellency, so it is a long strip stain in the warp direction, and the shape of the spots is smaller. Big, like cloud pattern.
5. Identification of raw spots and alkali spots
1) The locations of defects are different: Calcium spots are mainly the deposition of impurities on the surface of fabrics, most of which occur on the surface of the pot. The spots are caused by cooking and the location of occurrence is variable;
2) Use thinner Hot hydrochloric acid treatment can remove calcium spots, but the original spots cannot be eliminated;
3) The color obtained is different: the calcium spots are darker after dyeing, while the spots are lighter after dyeing.
6. Identification of alkali spots
Alkali spots will turn into yellow stains after drying, which can be seen on white cloth , and the pH value is above 7.
7. Identification of rust stains and oil stains
1) The shapes are different, and the periphery of the rust stains is not Regular, and the outer contour of the oil stain is relatively smooth;
2) After alkali treatment, the oil stain can be removed;
3) Washing with oxalic acid , rust stains can be washed away, but oil stains cannot.
8. Identification of oil stains and color stains
1) Slight oil stains can be removed with detergent. Color stains cannot;
2) The color varies, oil stains are light yellow or brown, oil repelles dyeing, and the color of color stains is often the same color of the dyed finished product. , or a single color of colorblock dye.
9. Identification of stains caused by floral wool before and after pad dyeing: There are floral wool on the fabric before pad dyeing, resulting in stains. Some parts are light in color. After pad dyeing, there are colored floral hairs on the drying cylinder, which appear as dark spots after dyeing.
10. The difference between roller stains and dye liquor suspensions: The roller has scars and unevenness, which means that the fabric is not easy to dry and the stains are regular. , stains and color stains are consistent in depth, and the dye is poorly dissolved or suspended matter exists, causing stains on the fabric.
11. Characteristics of oil stains and printing defects: mostly occur on thin and tight fabrics
1) The heavy stains are damaged due to washing, absorb more color, and have a darker color;
2) The oil detergent used for washing has not been washed, and the gray cloth has not been washed. There are impurities around the oil area, and the edges of the stains are repellent and the color is lighter. </p
