This article systematically elaborates on the accuracy and stability of the color and light symbols of the process, starting from the Analyze the factors that affect color light from three aspects: small sample, enlarged sample, and mass production, and put forward operational precautions based on practice. How to improve the accuracy and stability of the color light of dyed fabrics and adapt to customer requirements is not only related to the economic benefits of the company, but also related to the company’s reputation.
The accuracy and stability of the color light,
It is the soul of dyeing in the dyeing factory.
1. Proofing and imitation color
The new color list issued by the business planning department must first be carefully reviewed, such as: the standard samples must be complete, the light source must be clear, the fabric weave specifications must be clear, and the dyeing fastness requirements (soaping, rubbing, and sun exposure , chlorine resistance, dry cleaning, etc.) and finishing requirements (softness, waterproof, antibacterial, flame retardant, UV protection, etc.) must be exact, the sample delivery time must be reasonable, and if any problems are found, they must be understood in a timely manner with the business planning department.
Before sampling, the quality of the semi-finished products must be determined with the production planning department, such as mercerized cloth or unmercerized cloth, brushed cloth or unsanded cloth, white cloth or white cloth Bleached cloth, pre-set cloth or post-set cloth, pre-shrunk cloth or non-shrunk cloth, etc. The principle is: the cloth used for proofing must be consistent with the cloth used for mass production in the future to unify the process flow and process conditions, and it should not be changed on the way after being determined.
Before proofing, first determine the production method with the production planning department, such as whether it will be liquid jet dyeing or flat vat jig dyeing for large-scale production. Once determined, It is not advisable to change on the way. Because the proofing conditions of liquid flow dyeing and jig dyeing are different, the dyes and auxiliaries used are also different; if they are changed, the proofing can only be done again, and the proofing prescriptions must not be used interchangeably.
According to the customer’s color list, the dyeing depth and color brightness can be determined SpendAs well as dye fastness requirements, choose dyes carefully. For example, if you want to dye a deep color, use dyes with high strength, high darkening properties, and high wet rubbing fastness; if you want to dye light colors, use dyes with high leveling properties and high light fastness; if they are fast to chlorine bleaching, If the fastness to dry cleaning is required, chlorine-resistant dyes should be used; if dry cleaning fastness is required, dyes that are resistant to organic solvents should be used; when dyeing cotton nylon or cotton-polyester interwoven fabrics, especially when dyeing flash white or flash colors, it is necessary to Choose dyes that are less likely to contaminate each other. If it is nylon-cotton or cotton-nylon elastic fabric, when dyeing nylon, disperse dyes and neutral dyes or acid dyes must be well matched to ensure brightness, color fastness and surface uniformity to meet customer requirements. What should be pointed out here is that nylon and spandex have very different color absorbing properties (shades and shades) of disperse dyes. Dying nylon with disperse dyes alone has good level dyeing properties, but spandex often appears “different colors” on the cloth surface. “Silk” jumps out, affecting the uniformity and color of the cloth surface.
Before printing the approval sample, the original sample provided by the customer must be re-certified. The original samples provided by customers usually have the following situations:
1. The tissue specifications of the original samples are different from those specified in the color list. In this case, it is often difficult to match the color of the sample with the original sample due to the different light absorption, light reflection and light transmission of the fabric. At this time, you should make a few more samples with different shades and colors for customers to choose from, so as to increase customer recognition rate.
2. The original sample is not fabric, but printed cardboard. In this case, due to factors such as the smooth surface of the paper pattern, strong gloss, and the fact that the paper pattern is printed with printing paint instead of dye, the color of the dyed sample is generally difficult to match the original sample under the prescribed light source. At this time, we can only print a few more samples with different shades and colors for customers to choose from.
3. When dyeing cotton nylon or cotton-polyester interwoven fabrics, if the color depth and color uniformity of the bicomponent fiber in the original sample provided by the customer are poor, there may be Two-color phenomenon; at this time, there are usually two situations: the first is to retain this two-color effect; the second is not to have a two-color effect, but to uniform one color. Therefore, the shades of bicomponent fibers should be evened out (in the original sample, the shades of bicomponent fibers are different, which is due to poor dyeing uniformity). In this case, be sure to ask the customer clearly to avoid the sample not being confirmed.
4. The original sample has a certain fluorescence under the light source. In this case, be extra careful. There are generally two possibilities: first, the fabric is required to have a fluorescent effect under a specific light source; second, the fabric itself is not required to be fluorescent, but during dyeing, in order to enhance the brightness, fluorescent whitening is added.agent. At this time, you must first understand the customer’s true requirements, and then you can make a sample according to the requirements.
5. The original sample is silk fabric or acrylic fabric (or acrylic yarn), but the small sample must be made of pure cotton, or cotton polyester or cotton brocade. In this case, it is often because the original sample is dyed with acid dyes or cationic dyes, and the brightness is very good, so that the sample cannot meet the brightness requirements of the original sample. In this case, a similar sample must be made first for the customer’s reference, and the sample must be reported to the customer. The customer explains the reason. If fluorescent whitening agents are added for brightening, the customer’s consent must be obtained.
6. The customer’s color list often contains the “white” color number. For example: natural white, ivory white, pearl white, etc., but there is no physical standard sample. In this case, you need to clarify in advance whether the so-called “color light” in the color list refers to original white, bleaching or whitening. If the customer is confused about this and it is difficult to identify it, three samples of original whitening, bleaching and whitening must be taken first to give the customer approval. If it is identified as a whitening sample, three samples of yellow light, red light and blue light must be provided. , let the customer confirm. This situation must be taken seriously, otherwise it is easy to have color and light differences with customers during the acceptance of bulk goods, or even rework and repair.
7. For interwoven or blended fabrics such as cotton-nylon, cotton-polyester, polyamide-polyester, polyester-viscose, etc., the original sample provided by the customer is sometimes a flash sample (that is, the two fiber components have different colors and have a flash effect) ; For flash color samples, it is necessary to determine exactly which fiber is which color. Generally, it cannot be changed. If the color Color inversion generally results in two situations: first, the overall effect of the cloth surface is inconsistent; second, if the blending ratio is equal and the weaving specifications are appropriate, the overall effect of the cloth surface is basically similar, giving people an illusion, but leaving This eliminates potential problems, that is, once customers discover that the fibers are of the wrong color, they will refuse to receive the goods and must re-dye them. Therefore, you should pay special attention to flash color samples and not be careless.
8. The nylon and polyester contained in cotton, nylon or cotton-polyester fabrics are not all matte filaments, and sometimes there are glossy filaments. The strength of the luster of nylon, nylon and polyester has a great influence on the brightness and brilliance of the dyed cloth surface. Therefore, it is necessary to determine whether the nylon or polyester contained in the original sample provided by the customer is glossy or matte. If it is glossy, it must be sampled with the same fabric. If it is sampled with matte fabric, the color and light must be is inconsistent. If fluorescent whitening agents are used to brighten the color, customers usually do not accept it. Therefore, the customer’s approval must be obtained in advance and no one can make any own decisions.
9. The nylon component in the cotton-nylon interwoven fabric is usually nylon 6, but alsoThere is nylon 66. Since the amino content of nylon 6 is more than twice that of nylon 66, nylon 6 has a greater affinity for anionic dyes, good dyeing properties, and is easy to dye deep and rich colors. Nylon 66 is only suitable for dyeing medium to light colors due to its low amino content.
Therefore, before proofing, first try to ask the weaving factory about the type of nylon, and second, try to use nylon 6 blanks to dye a deep color. If the nylon 66 blank is dyed with a deep color, it is often difficult to achieve the depth requirements even if acidic bath and ultra-high temperature (100°C) saturated dyeing are used. Even if the small sample reaches the depth, the reproducibility of the large sample is often very poor, and there are also problems of low color fastness and serious sewage.
10. For twill fabrics with front and back sides, the twill side is usually the front side. Sometimes there are exceptions, and the back side is the front side. Therefore, it is necessary to carefully review the original sample provided by the customer. If you find that the reverse side of the color swatch in the color list is facing up, you must find out whether the reverse side is the front facing color, or whether the customer put the color swatch upside down. Never be empiricistic and make unauthorized changes, otherwise it will be a trivial matter to reprint the prototype, but it will be a big mistake if it is put into production.
22. Sometimes the color list provided by the customer includes both the original sample (usually different from the required texture in the color list) and the approved sample (usually The texture of the first approved sample entrusted to other factories is generally the same as the requirements in the color list), but there is usually a certain difference in shade or depth between the two.
At this time, there are generally two requirements from customers: one is to re-print the approval sample based on the original sample; the other is to use the first provided sample Accept the sample as the standard and re-sample it. In this regard, it is important to understand the customer’s intentions and not to make subjective assumptions. The proofing color sheets provided by customers generally have clear light source requirements, such as natural light, daylight, D65 light, TL84 light, CWF light, F/A light, UV light, etc.
In actual work in the factory, there are the following problems:
Standard light box
1. There are many brands of standard light boxes and lamp tubes used. Different brands of light boxes and lamp tubes have certain differences in the color of the light;
2. On the gray inner wall of the light box, stickPrescription paper and color samples, etc., will have a certain impact on the color and light. Therefore, when the standard light box is used for color matching, the color and light in the factory light box will match, and the color and light deviation will occur in the customer’s light box, resulting in small samples and large samples. Difficulty in color recognition.
Therefore, standard light boxes, especially light tubes, must choose products that meet international standards, and use light tubes correctly to eliminate non-standard light sources of light tubes and light boxes. The standard light box caused by improper use is not standard, resulting in color differences.
D65 light source
D65 light source is artificial daylight light source. Compared with natural light sources, their reactions to dyed light are not completely consistent. Some customers confuse the two and think that D65 light is natural light. Therefore, it often happens that the proofing color list stipulates D65 color matching, but when accepting small samples (or large samples), natural light color matching is used. Therefore, differences often arise between factories and customers. This must be communicated with customers to unify understanding and eliminate misunderstandings.
Different light sources
Some customers require the use of two different light sources for color matching, or even require the two light sources to be turned on at the same time and use a mixed light source for color matching. When encountering this situation, there will usually be an obvious problem of light jumping, that is, under different light sources, different colors of light will be produced, or even unrecognizable.
Different dyes have different structures, and have different light absorption and reflectivity for different light sources. If you want to solve the problem of color matching dyes (2~3 dyes) It is not easy to solve the problem of light tripping. The only way is to do a dye compatibility test and choose a dye with good compatibility with the light source. Under different light sources, the degree of light jump is relatively small.
When making samples for customer approval, the following principles must be followed:
① The cloth used for proofing must be Semi-finished fabric designated by the production planning department;
② The sampling method must comply with the production method approved by the production planning department (flat cylinder dyeing or liquid flow cylinder dyeing);
③ Must follow the quality requirements of the customer’s color listPlease select the dye;
④ The color light must be compared with the light source specified by the customer;
⑤ Required Proof based on the original sample (or first confirmation sample) recognized by the customer.
Under normal circumstances, the color depth of the sample should be controlled within 5%, and the color light should be controlled above level 4. If the texture of the original sample is seriously different from the approved sample, the color and luster can only be matched as best as possible.
⑥ The approved sample selected by the customer must be pasted together with the original sample provided by the customer as a basis for color matching for duplicate samples, lofting, and mass production.
It should also be noted that the original sample and confirmation sample provided by the customer must be signed by the customer. Because in actual production, it often happens that customers change the standard sample midway, or use another standard sample to accept the bulk goods, and then deny the original sample previously provided, thus causing disputes about the color and light of the bulk goods.
2. Staking out and trial production
Resample
Before setting out samples for trial production, you must carefully copy the sample according to the approved sample prescription. The following points must be paid attention to when copying samples:
1. The copying samples must use semi-finished fabrics prepared for trial production in the workshop;
2. Carefully check the duplicate semi-finished fabrics provided by the workshop. For example, whether there is the influence of fluorescent whitening agents; whether the sanding effect and bleaching whiteness are normal. If problems are found, contact the workshop in time and do not blindly copy samples to avoid trial production failure;
3. Duplicate samples must use the dyeing materials currently used in the workshop. Although the dyeing materials in the proofing room are changed once a week, there are always certain differences in strength, color, moisture content, etc. objectively. This will directly affect the accuracy of the lofting;
4. The duplicate sample work must be handled by a dedicated person, and a master of proofing with rich experience and good sample accuracy must be arranged. Duplicate. The person who originally made the approved sample should not arrange for duplicate samples. Practice shows that it is easy to find problems when replacing people and repeating the same process.Problems such as inconsistent proofing methods, improper dye compatibility, incorrect use of additives, improper proofing operations, etc. Problems must be corrected in a timely manner when problems are discovered, and strict precautions must be taken to avoid repeating mistakes or making the same mistake again and again.
5. The duplicate sample should try its best to match the color, luster and light of the original sample (or approved sample) identified by the customer. If it is a woven or blended fabric, the color of different fiber components must also have good uniformity, otherwise it is not allowed to be put out for trial production.
6. The review system must be implemented for duplicate samples, that is, the duplicate sample prescriptions for setting out and trial production must be reviewed and signed by others to eliminate errors and ensure the final steps. close.
7. After copying the sample, in addition to affixing the “replica sample” on the production prescription card, a semi-finished fabric sample for the copy must also be affixed. , so that the lofting personnel can check whether the quality of the control semi-finished products to be dyed is consistent with the semi-finished products for duplicate samples before dyeing, so as to ensure the stability of the lofting color light.
Source: Printing and Dyeing People
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