There is a color difference in the large vat, but customers are looking for goods! what to do?

1. Cleaning method

　1.Cold water cleaning

In cotton and its blended interwoven fabrics, if the cotton component appears floating or dark after being dyed with direct dyes or reactive dyes, it is generally necessary to continue washing with water, or add 0.5-1L anti-staining cleaning agent in the water bath. LEFIMIN (Lefimin) washable. If the water hardness is high, 0.5~2g/L chelating dispersant can be added to improve it. Avoid using turbid river water or deep well water with high hardness.

　2. Wash with warm water

When dyeing polyester blended interwoven fabrics, there are many types of dyes and auxiliaries used. Washing at 40°C can be used to facilitate the dissolution of residues stained on the fabric. Cellulose fibers are dyed with direct blended dyes. If the overall color of the large sample is darker than that of the small sample, the color will be similar after washing with warm water, and the color fastness can be improved to a certain extent.

　3. Hot water cleaning

Hot water cleaning is mostly used for silk or synthetic fibers and their interwoven fabrics dyed with acid, direct and basic dyes. If the color is darker, 1 to 20% of the dye needs to be removed, and you can use hot water washing at 70 to 80°C. For silk fabrics, 0.3 to 0.5L of leveling agent can be added to the hot water bath; for polyester, nylon and other synthetic fiber blended fabrics, 0.5 to 1.0L of patching agent or patching agent can be added. Dye carrier. Since the amount of additives added in the hot bath is small, the fabric only needs to be washed with running water to room temperature. If the dyed fabric is treated with cationic fixatives and softeners, it is best to add 2 to 4L of dispersant DAM to the hot bath. In principle, hot water washing (repair) should be carried out on the original dyeing equipment. For example, after jig dyeing of nylon, acetate fiber and interwoven silk, if the overflow machine (rope type) is used for hot water washing, the fabric will cause permanent wrinkles.

2. Additive Additive Method

　1. Add electrolyte

(1) When using direct dyes to dye cellulose fibers, the dyeing depth is often not enough for large samples. If there is still dye in the dye bath, add 1.5-5. Og/L electrolyte (NaCl, Na2SO4) promotes staining. This is suitable for salt effect direct dyes, such as direct lightfast yellow 3RLL, orange (L, bright red BNL, red 4BL, ruby ​​RNLL, purple BL, blue BL, B2RL, sky blue G, emerald blue GL, green 5GLL, green GL, gray 4GL, gray GB, etc. are very effective. For temperature-effect direct dyes, a certain temperature must be maintained.

(2) Use acid dyes to dye protein fibers, or useWhen acrylic fiber is dyed with basic dyes or cationic dyes, and the color of the dyeing sample is too dark or has flowers, 3 to 6 g/L Na2SO4 can be added to fade or level dye it.

　2. Add acetic acid

(1) Use acid dyes to dye silk, wool and other protein fibers. If the dyeing sample is lighter and there is still residual color in the dye liquor, O. 5-2mL/L 98% acetic acid promotes dyeing. The steam valve must be closed before adding, dilute it with 10 times cold water, and add it slowly while the dye is running to avoid causing new color flowers.

(2) Use K-type and KN-type reactive dyes to dye cellulose fibers. If the sample is too dark, you can add 2-3mL/L 98% acetic acid and treat it at 90-95℃ for 3Omin to promote partial bond breaking of the dye. Achromatic color can generally reduce the color by about 20%.

(3) When dyeing silk with alkaline dyes or dyeing acrylics with cationic dyes, if the sample is too dark, you can use 2~3mI/L acetic acid and treat it in a warm water bath at 4JD-60℃ for 20~30 minutes. The dye dissolves and becomes lighter by 20% to 30%.

3. Add leveling agent

(1) Use disperse dyes to dye polyester and its blended interwoven fabrics. When the large sample is darker than the small sample, a high-temperature leveling agent or repair agent can generally be added. If the color of the large sample is light, you should add the corresponding dye, but you should be careful to close the steam valve when adding to avoid color blooming. Add an appropriate amount of leveling agent first. In addition, when additional dyeing is carried out with disperse dyes, the temperature should be raised to a certain dyeing temperature and kept for 15-20 minutes, and then the temperature and pressure should be lowered and the sample should be checked.

(2) When dyeing cellulose fiber, silk, wool and nylon fabrics with direct, acidic, neutral and other dyes, in principle, O can be used to remove the migrating dye to achieve level dyeing. The amount of O added to wool fabrics generally cannot exceed 0.3g/L. In order to prevent the wool from felting, the wool protective agent Chromoplast WOK 2% to 3% (Dys-tar) can also be added. When dyeing nylon with neutral dyes, if the color of the large sample is too dark or there are rungs that need to be covered, using N-ER 3% to 5% (D’ystar) will have excellent results.

(3) When dyeing acrylic, alkali-modified polyester and silk with alkaline and cationic dyes, if the color of the dyed sample is slightly darker, you can use hot water to clean it; if the color of the sample is about 20% darker, you can When the residual liquid is basically washed away, add 2 to 4L of surfactant 1227 to achieve fading through competitive dyeing.

　4. Add whitening agent

When dyeing bright colors such as ruby, rose red, violet blue, azure, sky blue and brilliant purple, if you feel that the large sample is not bright enough, you can generally add 0.0015% to 0.0025% (owf) fluorescent whitening agent. The brighter the color The lighter the dosage, the less. For cotton textiles, the fluorescent whitening agent 4BK has a better effect. It has weak fluorescence, strong brightness, low dosage, good adjustability, and is adaptable to a wide range of colors and is not easy to “jump the light”. “Light popping” caused by fluorescent whitening agents can be removed with a fluorescent stain remover that does not affect the brightness of the color.

　5.Additional dyeing carrier

For polyester-cotton (viscose) and nylon-cotton (viscose), since polyester and nylon are hydrophobic fibers, their color is darker than hydrophilic fibers such as cotton and viscose. They can be added in a 60°C clean water bath. 2-4mL/L dyeing carrier, and then gradually raise the temperature to 80-9O℃ to slowly desorb the dye on the hydrophobic fiber to achieve the same two-phase color. Practice has proven that the dyeing carrier can not only dissolve disperse dyes on hydrophobic fibers, but also has the ability to dissolve other dyes. When the temperature rises to 80°C, the operator must continuously take samples to check, and generally keep the temperature until the large and small samples match.

3. Adding dye (pigment) materials

1. When adding disperse dyes to polyester for color correction, it is best to first lower the dye bath temperature to below 80°C, then fully dilute the previously dissolved dye, and finish adding it within 5 to 8 minutes, and then continue to increase the temperature to The original dyeing temperature is 15rnin or more for heat preservation dyeing to ensure that the front and back colors are evenly dyed to reduce the impact on heat setting.

2. If the color difference between the large and small samples is found after the dye comes out of the vat, you can add additional dye or adjust the color light on the large sample. When adjusting, in addition to calculating the variety and quantity of dyes required on the large sample, 15% to 20% of the original prescription dyes must also be added to the blank bath.

3. For colors made up of 3 to 4 dyes, such as rice gray, tile gray, fragrant gray, silver gray and ivory white, etc., dyes (pigments) cannot be used to repair the color difference between large and small samples.