With the development of technology, technical textiles are becoming more and more widely used, but…
In the garment manufacturing industry, one of the major issues is to determine the color difference of the same style of clothing pieces. Are you also facing the same problem to identify the color difference while dying your garment? Are you interested to know about the tools or techniques that can help you to measure the color difference?
If the answer to above-discussed questions is YES, then you are in the right place. Here we will discuss not only the techniques and methods to determine the color difference but also the reasons behind this difference.
1. The Garment Manufacturing Industry will always Encounter the Following Problems:
If you are working in the textile industry, understand the intricacies inherent in creating perfect tones. From raw materials to processing methods, the final appearance of your textiles depends on a large number of variables that must be carefully monitored to produce the colors you want. As such, color quality control is central to product development and manufacturing, helping to ensure that your products are at your level of vision. The following are details of those common problems commonly found in the Textile Dyeing section.
a) Fabrics with different batches and cylinder numbers will have color difference.
It is a common error that observed most of the time that as batch or cylinder number varies, we got different shades of color.
b) For the same batch, the fabrics of the same cylinder number will have a color difference.
It will be a surprising element for some of you that even the same batch on the same cylinder number can create a difference of colors. It means there are some more factors which are deciding the color scheme. In the upcoming paragraph, we have discussed the reason for these variations in detail.
c) For the same batch, the center and both sides of the fabrics of the same cylinder number will have a color difference.
Sometimes we also face such type of variation in which center didn’t match with the sides of the fabric. Such kind of change is very severe, and we need to encounter it immediately.
d) When customers inspect goods, if they only use the naked eye, it will cause a lot of color difference problems.
These type of variation also noticed that even can judge by the naked eye without using a particular kind of instruments. So, these are a different type of shade or color variation in the same fabric that we usually observed in the garment manufacturing industry.
2. Why is There a Color Difference?
The textile industry faces unique challenges when it comes to implementing robust color quality control systems. To understand the color difference, you must know the basic definition of the shadow and the difference in it.
Shadow is the depth of color ratio. The tone is expressed as a percentage of the amount of dye in the unit weight of the texture. Shadow adjustment depends on the accuracy of the man’s eye. It’s a visible process for this reason one tone can have different comments from a different person.
- Shade variation
It is the color difference or color depth (tone) difference in the same fabric roll or between different batches. In dyed fabrics, there is often a difference in shadows. The variation of shade can be done from the edge to the center of the cloth display or from the end of the cloth rolls to the other end.
Shadow or shadow contrast is a major problem in any fabric. A large number of orders are canceled because of the color difference between the pieces. Although there is tolerance, it is granted or established, but it is very difficult to maintain the same tone among all the draw.
a) The dyeing process is not strictly controlled.
Dyeing is one of the most advanced parts of textile production. It is a very complex procedure, so it is very difficult to monitor the whole process and strictly implement all the standards to get the desired results. There are several reasons why the pitch varies from batch to batch. Provided below:
- Preparation stage:
- Uneven pretreatment:Non-contrast, uneven color and discoloration cause changes in the tone. Use of chemical products with different concentration: If the level of the input chemical varies from one batch to another, a difference in color occurs.
- Excessive Heat setting:Thermal stabilization affects the formation of pigment bonds in synthetic fibers. The uneven and excessive heat setting can cause the shade to change.
- Workers’ Negligence:Due to worker negligence, shade variation occurs.
- Improper color dosing:Incorrect color doses can cause color changes.
- Rope length & Cycle time:If the length of the cable is the same but the cycle time varies from one batch to another, it can cause a variation of the shade. For example, if the time of the first batch cycle is longer than the results of the second batch, each part of the loop will not receive the same time to exhaust and install the dye. Therefore, the penetration rate of the dye becomes higher for the first batch.
- Fluctuation in power & temperature:The rise and fall in power supply and temperature are also responsible for the difference.
- Running time:Runtime is another factor for changing the pitch from batch to batch. Due to the difference in time of implementation of different stages of dyeing, the same work chemicals/dyes used in different batches also varies from one batch to another batch. Therefore, execution time can also cause a change in the shade from batch to batch.
- PH:Throughout the entire dyeing process, the pH has a significant impact on shade variation. In interactive dyeing, pH determination is necessary to achieve a uniform tone. Each dye appears under different conditions under different pH conditions. It was observed that if the pH of the polyester dye was not within range, the tone would turn yellow, dark, etc.
- Soaping:According to the depth of the shade; the amount of soap, soap time and temperature can change the shade and can produce variations in the shade.
- Improper neutralization:If the neutralization is not performed properly, residual alkalis can affect dyeing as well as change the color tone.
- Final cationic fixing operation:The installation process can cause shade contrast in the case of time and shade depth.
- Poor Lab-to-bulk Correlation:According to the laboratory, if the same percentage of liquor, recipe, chemical products, process steps, execution time, etc. are not followed in bulk production, there are many opportunities to get tone changes, as well as other process failure.
- Finishing stage:
Not only are the preparation and dyeing processes important, but the final finishing process is also important to avoid batch-to-batch change.
- Unequal drying temperature:If the drying temperature is uneven, a difference in shade occurs.
- Softener quality:According to the difference in the quality of the softener, change, nature, concentration, pH, etc., can be observed variation of chromaticity during finishing.
b) Improper storage and transportation of fabrics.
Improper storage and transportation are also one of the causes of color variations in fabrics. There are many things that are involved in dealing with fabrics. Fabric handling can be defined as: “Art and science of transport, lifting, positioning, transport, packaging, and storage of fabrics”.
From the moment, raw materials (such as fibers for yarn unit or threads for textile / textile unit and wet treatment fabrics or garment units) enter the mill door leaving the mill door in the form of finished products; It deals in all stages within the factory boundaries, such as inside and warehouses of raw materials, various sections of the production department, shops from machine to machine, and finished goods stores. The material can be treated up to 50 times or more before it changes to the finished product. The common cost of material handling is estimated at approximately 10-30% of the total cost of production, depending on the product to be treated. By saving on the cost of material handling, production cost can be drastically reduced. Material handling involves moving material manually or mechanically in batches or one element at a time within the factory. The movement can be horizontal, vertical, or a combination of these two.
Principles of fabric handling
In general, principles of material handling are as under:
- To speed up material movements, use mechanical means rather than manual labor.
- Minimize the movements involved in the production process.
- To transfer an ideal number of pieces in the unit; use container principles, unit load or palletization.
- Reduce the distance you make by adopting shorter routes.
- To reduce back movement and dual processing. Change in the sequence of production processes.
- Material handling equipment of appropriate size, standards, efficiency, effectiveness, flexibility, safety and proper size should be selected.
- To minimize damage to materials during handling and extraction of material handling; design of cars, packages, containers, drums, etc.
- Use, if possible, gravity to help move the material whenever possible.
- To avoid any interruption in handling, the material handling, repair and maintenance equipment should be regularly reviewed and maintained.
- Handle equipment parts in a way that minimizes the distances between the by-products that move, and at the same time, the handling of objects should not interfere with another machine or process.
c) There is acertain color difference in the same batch of the same cylinder fabric.
Shadow change is a common and important problem for dyeing industries. Many reasons are responsible for the difference in shade in textile dyeing industries. Notice the color problem from batch to batch when the fabric is dyed in a small batch to complete the order quantity. From a comprehensive examination, it was noted that in most cases, a change in shade occurs due to lack of concentration and lack of adequate service by the operator of the machine concerned. Most of the time, there are different errors in dyeing, such as shade differences, because of irresponsibility by the administration concerned in the dyeing floor, along with some technical problems. Maintenance is also a hot fact for shade diversity. To maintain the device, it is essential that the maintenance department is strong and efficient enough. Shadow variation is undesirable and unexpected for a textile engineer and also for dyeing the production floor. It is the responsibility of the responsible authority on the dyeing floor to keep production away from the different shade between all batches of requests along with all dyeing errors, including through proper performance, along with maintenance of all procedures and parameters without dyeing problems. Word.
Dyeing is the main section of the fabric where the coloring is performed on the fabric substrates. In dyeing, many problems arise, including shade change is the most unusual and most appropriate problem. Every time there is a failure of color difference during dyeing, the process must be recorded, which enhances some loss of productivity. It is essential that dyeing companies maintain a higher level of quality in dyed fabrics to maintain a good relationship with buyers and other companies. The push to bold running in dyeing is of great importance in the textile sector. The textile sector is a leading field of socio-economic activity, with regard to its technological status, economic efficiency and social interaction. Faults such as shadow contrast will result in lower quality with production rate and reputation. The shade is the color depth or percentage of the pigments in the fabric. Shade is expressed as a percentage of the amount of dye in a unit of mass of tissue. Shadow adjustment depends on the accuracy of the man’s eye. Shadow accuracy varies according to the visual sense of pigment dyeing to the dye master or the person to the person. Therefore, an expert in dyeing or expert is needed for this purpose. In addition to the manual color adjustment system, the newly enhanced color of computer data is also used to accurately measure tones as a spectrometer. In this case, the color is compared in a standard manner approved by the buyer or the corresponding responsible authority. All batch tones are measured according to this standard tone in the same order. In the dyed fabric, the hue variation can be found roll to roll from meter to meter and, together, the dishwashing band, center to side, end to end, from the nozzle to the nozzle, etc. a problem in the dyeing industries that will hinder or cancel Strongly order, shipment or production process. Although tolerance exists, it is granted or established, but it is difficult to maintain the same tone in all contracts, but can be maintained within the range of 0 to 1 according to CIELAB.
Quality is of paramount importance in any aspect of work. In dyeing, batch-to-batch execution is a major concern, as well as dyed cloth. Since customers are end users of garments, it is necessary to dye quality and maintain it appropriately to maximize satisfaction.
3. How to Measure the Color? And the Color Tolerance Range?
Is the color difference between the sample and the accepted standard?
The ultimate goal of the color process is to get the color you want, or what the customer wants, for the final product through an effective and improved process. If the product color does not match the standard, customer satisfaction is compromised and the amount of rework, waste, and costs increases. Objective color creation within the color process is an effective way to maintain color consistency and accuracy, as well as to meet standards more efficiently.
Color tolerance is the limit to the color difference between sample and standard so that the sample is acceptable. To use color measurement tools, tolerance values must be determined internally or between the supplier and the client, and used in quality control to determine whether the sample is being inspected. To create color tolerance, here are some steps to follow:
a) Define a color standard:
What color do you want to have the finished product? The standard must be defined internally or between the provider and the customer. Using color gauges, measure the color you want to match with the final product and record its color values.
b) Perform visual assessments:
What colors are visually acceptable? Visual assessments are performed to link human visual perception with numerical values of color. To start, collect samples or lots of colors that have a similar color to the standard and visually evaluate them using a light booth. Select colors visually different from the standard, but still consider the matching acceptable with the standard. Once the visual assessments are completed, collect samples for measurement.
Keep in mind that the sensitivity of the human eye varies from person to person, making it different from each color. Therefore, it is recommended to use a committee of people to confirm these visual assessments and maintain consistency.
c) Define tolerance values:
What is the scope of acceptance? Measurements for each selected sample of visual assessments using a color scale or spectrophotometer. The color difference between each sample and standard should be recorded as ΔL*, Δa*, Δb*, ΔC*, ΔH*, and ΔE*, depending on the color area used. The sample color can be used with values farthest from the standard color as a maximum tolerance.
Note that these values must be reassessed during the manufacturing process and continually revised to determine the optimal tolerance values for your application.
d) Establish a tolerance system:
Elliptical, rectangular, or circular? Tolerance values must be linked to the human eye so that the color is visible and numerically acceptable. The system ensures consistency tolerance from one batch of material to the next. Therefore, it is recommended to use the elliptic tolerance system, such as CIE2000, because these systems depend on the threshold of chromatography of the human eye. Elliptical bearing systems have been created to address weaknesses in other tolerance systems and improve accuracy.
The maximum tolerance values specified in step 3 are ellipsoid around standard color. The color that falls within the specified elliptic tolerance range is acceptable, while the color outside this elliptic shape is rejected.
High-resolution color measurement tools and color analysis software, such as Spectra Magic NX, make it easy to define tolerance values and identify inconsistencies between the ample color and standard color.
4. Usage of Different Light Sources to Measure the Color.
Problem that occurs naturally, this color or tone looks different when viewed in different lighting conditions.
The difference can be extreme and clear. For example, a bright red car may appear in broad daylight under a general lighting of sodium. But in supply chains, even minor differences in perceived color can be problematic.
Color accuracy is a major concern for manufacturers who are asked to provide products with subtle shades. Color control does not work in natural light due to lack of normal natural light. It varies according to the time of day, season, location, climate, weather and weather conditions.
As a result, colors can look that look good when they work poorly when delivered. If disputes arise, how will they be resolved?(It should be noted that recognition of color differs from one person to another and that everyone can recognize several million colors, and as expected, it may be difficult to get even two people to agree that a particular tone is “right” or “wrong”.)
The solution is a range of products based on:
- Standard industrial light sources.
- Special bulbs that imitate daylight according to international standards D65 or other standards set by major retailers.
If everyone in the supply chain uses the same agreed light source, the differences in natural light become irrelevant. Color can be seen and measured in the same lighting conditions at each stage of product design and development.
Standard synthetic lighting sources evaluate colors quickly, accurately, equitably, economically, and globally when supply chain partners use the same light source to share data.
In industry, color assessment plays an increasingly important role in quality assurance. For reliable results that everyone can agree upon, there are three basic requirements:
- High quality light source.
- Standard supply conditions
- A way to capture objective data.
Let us look at each one in more detail:
1) Light sources
Finding the appropriate light source for a particular application depends on these three factors:
a. Color temperature
Color temperature is not related to heat. Describe the appearance of light from the lamp. The lower the color temperature, the “warmer” it is (red). The higher the temperature, the “colder” (bluer) is light.
b. Color rendering index (CRI)
The index measures from 0 to 100 the accuracy with which the lamp generates colors compared to the reference light source. Low values indicate a poor chromatic representation, while the value is 100.
c. Spectral power distribution (SPD)
Different light sources emphasize different parts of the chromatic spectrum, affecting the way the eye perceives the color. The SPD rating classifies each light source.
2) Standardized viewing conditions
All supply chain members must ensure that supply equipment and environment comply with internationally agreed standards. The color evaluation cabinets shall contain interior designs in gray, matte, neutral, flawless, high-quality lamp reflector and non-deformation.
3) Capturing objective data
Color evaluation has traditionally depended on human vision. One weakness of this practice is that, even in standard viewing conditions and so far, when residents have considerable experience, different individuals can see the same color differently.
It is also impossible to record what the human eye sees objectively. Some provisions must necessarily be subjective, making communicating with reliable color data problematic.
5. Usage of Grayscale Card to Measure the Color
Grayscale is used to evaluate color shading between products and a sample of customer approval or between parts of production. Gray scaling contains 1-5 grades and increases in the first row (1, 1 1/2, 2, 2 1/2, and so on). Five are the top. In general, most overseas customers can accept a grade higher than 4, while some can take 3-4 grade.
Another gray scale is for color coloring. It is mainly used to evaluate stains on wet cotton and dry white rags, in a professional laboratory. The worker is usually bound with white cotton to the sample. After that, they will put them together in the washing machine and watch the result. The inspector generally cannot do this on the site because equipment and time are limited. Alternatively, the inspector can conduct a rub test to color coloration. To do this, the inspector must prepare two pieces of white cotton cloth: one wet and the other dry. The inspector will inspect the production sample 10 times with both 9N (1 kg).
- Expected result:
There should be no worse grade 4 color transfer on a grayscale (between the original white cloth and color) after the dry test.
Do not transfer the worst color of 3-4 to the grayscale (between the original white cloth and colored cloth) after moisture test.
To make the most of your results, the inspector must ensure that the method and outcome are explained and clearly explained to the manufacturer. The factory must be able to help, for example, by providing a 100% cotton white cloth with excellent quality and providing good lighting and conditions for the room. In a textile check, the inspector’s experience is important when testing, so be sure to use an approved quality control provider!
6. Usage of the Computer to Measure the Color
The work procedure for the computer color matching system used in the dyeing plant is compatible with the tone of the products. In general, the buyer gives the product a sample of tissue or a pantone number for a specific shade. The product delivers the tissue sample to the Laboratory Immersion Development Section to match the fabric color. After you obtain the sample, analyze the sample color manually. On the other hand, they can get help from the computer color matching system.
Initially, you must adjust the sample to a lab that analyzes the depth of the shadow and displays the results from the color depth. At the same time, you must select the color combination you want to dye the cloth out. Then you will generate a recipe for almost identical dyeing. Here you must determine the amount of chemicals you want to use during dyeing.
After forming the dyeing recipe, it is necessary to dye the sample with the mother solution. I think you are also familiar with the stock dissolution. The sample should then be dyed according to dyeing procedures. After dyeing the sample, the sample stained with the buyer sample should be compared. For this reason, the stained sample is introduced into the spectrometer to analyze the sample with a sample from the buyer.
CCMS then yields pass-fail results. If the sample matches the buyer’s sample color, CCMS gives the pass-through results. After that, the stained samples are sent to the client or buyer. After obtaining the buyer’s approval, the product goes into bulk production.
If the color match sample does not show the buyer, CCMS analyzes the color difference and corrects the recipe, then perform the other dye sample to match the pitch of the sample.
Advantages of Computer Color Matching System (CCMS) :
- System CCMS has many great advantages in the textile industry. See some examples below:
- Customers get the exact tone required with their knowledge of the extent of the extension.
- Often customers mostly choose from 10 to 20 combination match color. By taking into account the cost, availability of dyes and auxiliaries, one can choose the best sample.
- 3 to 300 times faster than manual color combination.
- Limited set of stock color required.
If we take a bird’s eye view or want to get the gist of all this discussion, it will reveal on us that although it’s a complicated process to get precisely matched the desired color, but, by understanding the problem, usage of proper tools to determine the quality and good monitoring system, we can achieve it.