Colour Fastness
By: Everything Cj
Tags: Tutorial, Colour, Guides And Tutorials, Colors, Details

Colour Fastness

Colour Fastness

1. Definition of colour fastness: What is colour fastness?

Another name for colour fastness is dye fast. It refers to the resistance of fabric colors to influences such as changing or changing colors during processing and use. The accuracy grade, i.e., the degree of color fastness of the fabric, is evaluated according to the color of the sample and the staining of the unbroken lining fabric.

Fabrics are generally exposed to external factors such as light, washing, ironing, perspiration, abrasion and chemical agents. Some printed and dyed fabrics are also subjected to finishing processes, such as resin finishing, fire extinguishing, sand washing and grinding. This requires that the color of the printed and dyed fabrics be maintained at a certain speed, i.e. good color fastness.

2. Damage to the weak color velocity of the fabric

The danger of rapid discoloration of the fabric is somewhat noticeable. When fabrics with poor color speed are exposed to water, sweat, sunlight, or physical exposure, the dye may eventually fall off or fade. Thus, the appearance of the fabric product is negatively affected. During use, mud dye molecules or heavy metal ions are absorbed by the human body through the skin, which can endanger the health of the user. In short, weak colors are unacceptable fast.

3. Classification of color fastness, what are the different categories of color fastness?

In fact, the ultimate use of a product and product standards is to determine the test components or conditions used. For example, according to the wool fabric production standard, manufacturers must test the color of the wool in the sun. Of course, the sweat color of knitted underwear should be tested for color fastness, and outdoor fabrics (such as parasol, lightweight box fabric, canopy material) should be subjected to a color fast test for weather resistance.

There are six common color fast classifications:

3.1. Rub the colors faster

Acceleration of rubbing is the amount of color fading of the dyed fabric after rubbing. This can be dry rubbing or wet rubbing. The rubbing speed is determined by the size of the white cloth and is graded by 5 levels. The larger the value, the higher the rubbing speed.

3.2. Lightness

Lightness is the degree to which colored fabrics fade when exposed to sunlight. The color acceleration light test performs a standard color sample divided into eight grades by comparing the fade size of the sample after simulating sunlight; 8 indicates its best value as a result value and 1 indicates its worst value. In summary, in order for fabrics to remain optimal, they should not be exposed to the sun for long periods of time and should always be dried in the shade.

3.3. The speed of coloring

This is the amount of pigmented dyed fabric stored. Grades 3–4 of this category are usually required to accelerate the dyeing of normal fabrics.

3.4. Washing clothes fast

Washing or soaping is the amount of discoloration of the dyed fabric after washing with a washing liquid. Usually a gray rated sample card is used as the evaluation standard; That is, the color difference between the original sample and the faded sample is used for judgment.

The washing speed is graded to five levels; Grade 5 is the best and Grade 1 is the worst level of fast washing.

Weak laundry should be dried and cleaned quickly with a damp cloth. But if they need to be wet-washed, you may want to take a closer look at rubbing other laundry conditions. For example, the washing temperature should not be relatively high and the washing time should be kept short.

3.5. That fast for sweat

The faster the color of the sweat, the greater the amount of color fading on a dyed fabric after a small sweat.

3.6. That the iron color is fast

This refers to the extent to which the dyed fabric can be dissolved or ironed.

4. How to judge different types of color fastness and how to prepare for a color fast test?

Color speed is a relatively broad topic and is based on professional knowledge, and it is important to know a few basic concepts and tools that will help you understand when you read.

4.1 Color Speed ​​Testing Terms

The color is different

When printing and dyeing fabrics under specific environmental factors, the chromosome, color, and brightness of certain textures and reactions in the fabric may change. This effect is called color. Fabrics include some of these events; When part of the dye separates from the fibers or when the bright group of dyes is destroyed or a new bright group is generated.

Staining

Staining is the process of separating a portion of the dye from a piece of fabric from the originally attached fibers and transferring it to other lining fabrics when exposed to various environmental factors, thereby staining the lining fabric.

For garments consisting of different colored parts, the dye sometimes transitions from one area of ​​the fabric to another, during storage and usually from dark to light parts. This phenomenon differs from fluctuation in that it occurs at temperatures lower than room temperature, and is caused by dyes that are not exposed to sunlight. We can see this in the transition of dyes in polyester and other chemical fibers as well as in other raw materials.

Color transfer occurs for two main reasons: the first is the change of dyes, especially floating color dispersion and reactive dyes. These dyes can be transmitted and released from the fibers by dyeing the surface of another sample. This is usually done in dark colors, which are light colored dyes and the other samples have a granular and embossed surface. The second is that the fibers fall under the friction process and move from one sample to another.

4.2 Common grading tools for color acceleration

The color acceleration of the fabric is graded by the coloring and staining of the gray cards. Currently used gray cards include AATCC gray cards, ISO gray cards, JIS gray cards and national standard GB gray cards. These gray cards are slightly different from gray.

Color fast grading gray card is a card characterized by an increase or decrease in a specific grade. A color-changing gray card consists of a standard set of gray levels and a set of color-changing gray levels. The initial gray levels remain unchanged throughout the experiment, while the second group of color-changing grays gradually decreases and the color changes between the two.

Gray card that changes color

This opposite card has one standard gray scale and a decrease in the gray chromosome.

The grading of grays for color change is determined by the Grade 5 and Grade 1 grades, which represent the best Grade 5 and Grade 5 speeds. The middle level can be assessed as semi-grade: grade 4–5, grade 4 and grade 3–4.

Stained gray card

It consists of a standard white scale with a corresponding group of gray chromosomes. There are five grades and nine grades; Grade 5 indicates that there are no stains. Grade 1 therefore indicates the worst color fastest and can be rated as mid-grade 4–5, grade 4 and grade 3–4.

From the above data it can be seen that the so-called grade reduction method appears in the form 1: 2: 4: 8: 16. The gray card looks at the grade level of the color change, so you should monitor the grade level of this change when grading. Then there will be no such thing as a gray and black assessment, but no other colors.

4.3 How to use color fast gray card correctly

The cover card (as shown in the image above) is used for grading. Each hole is used for multi-fiber fabric stain evaluation, rapid stain evaluation, and general stain evaluation (self stain color evaluation, single fiber stain evaluation).

The use of mask cards is more conducive to focusing on the samples required for grading while other colors are covered and do not affect the other color vision.

When grading, the cover card should be connected with the sample to be graded, keeping the smallest gap in the back panel to prevent color exposure and affecting the display. Be sure to use the cover card to cover the original sample and the sample to be graded and keep the graded gray card level.

4.4 Environmental requirements for color fast grading

Light sources and equipment

The most preferred standard light source is the D65 light source. Its service life is 2,000 hours. Customers can also specify other light sources, such as F light source, 84-P light source, and ultraviolet light source.

Environment: Dark room

The grading process should be carried out in a dark room with constant humidity and constant room temperature. The color of the wall in the dark room and the objects on the wall should also be painted in neutral gray, which is similar to the grading gray card between level 1 and level 2 (roughly Monsel color card N5). As shown in the picture above, the left side is a neutral gray wall when the lights are on and the picture on the right is when the lights are turned off. It is essential that there are no other light sources in the dark room other than the light source in the rating light box. Also, make sure that no other sunlight is shown on the rating platform.

Serial angle

To use the gray card for grading samples, you must use the correct grading angle. The generally used standard is that the sample and horizontal plane should be at 45 and the light source and sample for grading should be 45 at. The grade should be 90 at to the eye sample and the distance between the eye and the sample should be 50–70 cm.

Personnel Needs

The grade should not be color blind. They can be tested using a color-blindness detector or a Farnsworth-Manzel 100 color test kit.

Clothing Requirements: Gray clothes are best. Avoid brightly colored clothing, brightly colored nail polish, and any items that may reflect light sources.

Do not wear stained glass.

Do not underestimate when you are tired or sick. Grading is a subjective activity and the mood influences the mental, subjective judgment of colors; For the same sample, when one is happy, it is one result. It’s another thing when they go down.

Observers should adhere to standard lighting conditions for at least 2 minutes before starting observation. This allows the eyes to adapt to current light sources.

Assessors require rigorous training and must pass a pre-determined assessment.

Different groups are required to perform eye calibration on the same sample from time to time and ensure that the error between groups is minimized. Occasional eye calibration between laboratories is also required.

The grading function shows the results of the color acceleration test and is the final step in the color acceleration test function. No matter how accurate and standardized the previous processes are, there will be errors in the ranking, and all previous attempts may be in vain. With regard to the current color fast testing, the ranking is always a difficult task to manage. On a small scale, it is necessary to ensure the conformity of the eyes of all persons in the laboratory. On a large scale, there is a need to ensure eye compatibility among testing institutions. As each brand collaborates with many labs, eye-to-eye compatibility between labs is especially important.

5. Detailed explanation of different color fast tests

5.1 Acceleration of color brushing test

Speed ​​dyeing is a type of fabric and speed testing is one of the most commonly used tests in the textile trade. It refers to the ability of a fabric to resist vibration, both dry and wet.

5.1.1 Rubbing color acceleration test model

This model was typically used to test the color fastness of a fabric to fit a specified size fabric sample on a diagnostic test platform with a clamping device. Then wipe with a dry wipe cloth and a wet wipe cloth respectively. Finally, the white fabric staining level is used as the basis for evaluation, and it is graded against a standard color fast set for gray scales staining.

The gray sample card used to determine the fast rating is divided into five grades; Rub as fast as the grade increases. A fabric with a low spinning speed can wipe the dye off basically anything and is unsuitable for end users.

5.1.2 Dry diagnosis test

Standard atmosphere (temperature 50 ± ± 50 ℃, humidity 20% 2%), humidity control for more than 65 hours (4 × 4) mm. Make sure that the direction of the friction cloth corresponds to the direction of motion of the friction head. Adjust the rotation speed of the rubbing head to ten times one inverse dialectical cycle per second, which is a total of 10 detection cycles. The detection angle or inverse motion of the sample is measured in mm. Should be (104 ± 3) and the direction of application is vertically downwards. This downward force should be (9 ± 0.2) n. At the end of the full ten cycles, remove the diaphragm, adjust the humidity (more than 4 hours), and remove any excess fibers on the diaphragm that may affect the grading. As shown:

5.1.3 Wet Diagnosis Test

Dip one foot into warm paraffin 3 times, pausing between layers to allow them to dry, then reassemble the fabric and ensure that the moisture content of the fabric reaches 95% -100%. Then use the same operating system as in the dry vision test.

5.1.4 Textile Rubber Resistance Testing Rating

After performing the above test procedure, we should take the damp vision cloth to the grading room and place it in the standard light source box, then use the gray sample card to assess the stain grade of the detection fabric.

Place three layers of fabric on the back as shown in the figure)

5.1.5 General standards for fabrics Accelerate color comparison

The most commonly used standards for color acceleration are GB / T 3920–2008, AATCC 8–2007, AATCC 116–2010 and JIS L 0849–2004. We can analyze the similarities and differences between these four standards through the table below.

This table shows that different test standards have different requirements depending on the size of the sample fabric. When the customer prepares the sample fabric, if the sample tested is fabric or carpet: 50 × 140 mm. Make two sets of samples of no less size and group each set into two parts. (When sampling, one piece of fabric is parallel to the warp yarn and the other piece is parallel to the weave yarn.) Another sampling method involves sampling at a specific angle from the sample length to the type and valve. Fabrics.

If it is easy to distinguish between piles of fabric and piles, the direction of the piles should correspond to the length of the fabric when the sample is cut. Under normal circumstances, the national standard and the European standard follow the pattern of taking one piece in each latitude and longitude direction. In contrast, the American standard follows the sampling method with an inclination of up to 45 degrees.

If the fabric yarn tested: It should be woven into fabrics with a sample of not less than 50 mm and not less than 140 mm. Alternatively, the threads can be wound parallel to the cardboard of the same size as the sample and along the length of the cardboard.

5.1.6 Analysis of factors affecting color acceleration by rubbing

Influence of fabric surface morphology

Under dry conditions, it is very easy to rub dry on a rough surface or to sand and upholstery such as hemp, denim and pigment printing fabrics. This is because mismatched dyes are a major cause of poor color scratches. This is because dye, paint, or other colored material that has accumulated on the fabric surface has fallen to the floor. Some colored fibers are even broken and color particles are formed, which accelerates the color by rubbing dry. For sandy or raised fabrics, the surface of the fabric and the surface of the fabric are located at a certain angle that is not parallel, which increases the resistance of the head to the vision during recycling, and this type of fabric is resistant to drying. So rubbing reduces color acceleration.

Effect of fabric structure

The surface of a light and thin fabric (usually synthetic fibers or silk) slides with the movement of the specimen head during dry dictation, during sample speculation, and under dictation activation. Slipping partially increases the resistance of the test and also increases the efficiency of the test. But in wet vision with these chemical fibers, the reaction is different from the reaction with cellulose fibers.

Due to the high moisture absorption of the fibers or the presence of water as a significant spraying effect and lubricant, it is better to dye such light and thin fabrics faster than wet rubbing their color fast.

Therefore, it is not uncommon for some fabrics to have a better color speed than wet coatings. In these cases, the selected dyes, dye activation, dyeing, finishing process conditions, etc. also affect the rapid application of the pigment. But their effect does not seem to be so significant when compared to the influence of physical factors such as the texture and surface morphology of the fabric.

However, studies have shown that this effect generally applies to darker colored products such as black, red and navy blue. In fact, under wet conditions, due to the dyeing, printing and dyeing processes of Koduroi, Twill and other pigment printing fabrics, the wet rubber grade generally has a level 2 or lower color fastness, which is not superior to their fast drying.

Effect of reactive dye chemical structure

When cellulose fibers dyed with reactive dyes are subjected to a rapid test of wet rubbing, two main factors can cause color transfer: the water-soluble dye is transferred to the rubbing cloth while rubbing the dye, thereby erasing the original color. Wash clothes. Second, when dyeing, some of the dyed fiber breaks down to form smaller colored fiber particles, which are then transferred to the rubbing fabric.

Factors affecting the color of wet dirt in reactive dyes include the structure and properties of reactive dyes, the properties of the fabric, the effect of the pre-treatment, the surface damage of the fabric, and the surface finish. Furthermore, the dyeing process and the effect of soap after dyeing, the effect of the treatment fixation and the dyeing effect of the dye all contribute to the color fastness of the reactive dyes.

Studies have shown that the covalent bond strength, bond stability, and adhesive formed by the reactive dyes of various chemical structures on cellulose fibers vary. On the other hand, there is no significant difference in the effect of color acceleration on wetting the dyed fabric. When the dyed fabric is wet, the cohesive bond between the dye and the fiber will not be broken; Therefore does not produce floating colors. Transferred dyes are usually ultrasonic dyes that do not covalently bond with fibers and rely solely on van der Waals forces to produce adsorption, which is the so-called floating color.

Effect of degree of reactive dyeing

Reactive dyes accelerate the dyeing of dyed fabrics, which is closely related to the dyeing depth, as the amount of color transfer and the dyeing depth are in good linear relationship when wet rubbing. Excess dye cannot be fully integrated with the fibers. They are added to the fabric surface to create floating colors, which seriously affects the fabric’s ability to accelerate.

Cotton fibers without special treatment and under wet conditions swell, increase vision and reduce fiber strength. These create favorable conditions for breakage, shedding and color transfer of color fibers. Therefore, pre-treating cellulose fibers before dyeing can improve the surface finish of the fabric and the hair effect. Among these pre-treatment procedures; mercerizing, singeing, cellulase finishing, scouring, bleaching, washing and drying. This reduces the resistance to vibration and reduces the floating color, thereby improving the color fastness for wetting fabrics.

Softener effect

With a soft finish we can improve the color fastness of the reactive dye printing. It has a softening lubricating effect when applied to fabrics and can reduce the coefficient of dyeing to prevent the dye from falling off. Cationic softeners can form lakes with anonic dyes and the dyes do not fall off easily. At the same time, the formation of color lakes ultimately reduces the viscosity of the dyes and increases the wet rubbing speed. However, softeners with hydrophilic groups often improve color fastness. In the manufacturing process, the water-soluble group of dyes can be blocked using a fixing agent. With this, the pH of the finished color fabric surface can be controlled, the floating color can be removed, the smoothness of the fabric can be improved, and the wet rubbing speed of the fabric can also be improved. Proper baking in the front stage can prevent the “transition” of the dye.

In pre-treatment, factors and properties that need to be considered are the amount of alkali, the vapor time, the washing method, the amount of soap, and so on. The first two are closely related to the level of hydrolysis of the dye and the second is directly related. The dye is related to the floating color.

Adequate washing, soap, and other processes should be performed to remove dyed fabrics, especially long car pads, floating paint and non-reactive and hydrolyzed dyes on the fiber surface. This will prevent adverse effects on the color speed of the fabric, but it will also weaken the color speed, making the shade darker when not getting the attention it deserves.

Among the factors mentioned above, laundry is fast and the principle of their activation and the magnitude of the effect are quite different. The problem of color fastness seems simple, but the factors involved are somewhat complex. Over the years, people have invested a great deal of manpower and material resources in solving the problem of color fastness in textile products, whether in dye research and production, dyeing and finishing. Thanks, great progress has been made. Although dyes, new processes, and new additives continue to emerge, there are still many problems that need to be solved.

5.2 Fabric light food test

The lightness of the fabric has gradually attracted more and more attention locally and internationally. Today, the production standards of the Chinese textile industry (especially new standards approved in recent years, except for the underwear standards) are all used as one of the standards of lightness assessment. For example, China’s previously published silk production standards have not been mandated to assess lightness. However, the published standards have now taken the lightness of elastic silks as an assessment indicator. Lightness with chemical fibers such as silk fabrics and cotton product standards is considered an important evaluation indicator, while some product standards are considered an evaluation indicator for lightness.

5.2.1 Comparison of common test methods and standards for lightness

There are many test methods for lightness. The table below lists some of the most commonly used standard methods.

5.2.2 China’s current effective ease testing test standard

Light coloring: This is done by exposure to the sun under certain conditions, not by exposure to rain. The light color velocity of the suspicious sample is then evaluated according to the blue wool standard.

- Acceleration to artificial light: Xenon arc testing is the exposure of a sample to an artificial light source similar to sunlight under certain conditions. The light color speed of the sample is evaluated relative to the blue wool standard.

- Acceleration of the weather: This means exposing the sample to the outside without any protection and under certain conditions. The sample is then compared with the blue wool standard to assess its color fastness.

Man-made weather-accelerating colors: This refers to the use of xenon arcs to spray exposure in a xenon lamp tester under specific conditions. The exposed sample is compared with the blue wool standard to assess color fastness.

Composite Color Acceleration for Light and Sweat: Expose the device’s sweat treated sample, then assess its color fastness to light, and apply sweat to determine its sensitivity. Among them, the xenon arc, which has the color speed of artificial light, is the most commonly used standard. Many fabrics in China are tested according to this standard method when assessing the color fastness of light.

5.2.3 Relevant standards of the American snack tester

Color acceleration is ideal for indoor fabrics. The weather resistance of the fabric (via xenon arc) is suitable for outdoor fabrics. Among them, lightness is the most commonly used fabric light resistance and stability standard.

Its main measurement range is:

Dye Lightness Testing: Dye lightness testing is measured under light (wavelength 380nm ～ 750nm) and under certain temperature and humidity conditions.

Weather acceleration test of dyes: The weather speed of dyes accelerates under the combined influence of light (wavelength 380nm ～ 750nm) and a certain temperature, humidity and precipitation.

Weather velocity testing of fabrics: The weathering of fabrics is accelerated under the combined action of light (wavelength: visible light = 380nm ～ 750nm; ultraviolet = 300nm ～ 380nm) and climatic conditions.

5.2.4 The best way to test lightness

The reaction of the fabric to light is one of the most important test components of all color fast tests. Of course, for manufacturers, laundry, dry cleaning, scrubbing, sweat absorption, and exposure to various solutions are crucial information. However, accurate and reliable testing is very important because fabrics are sensitive to light and it is difficult to predict their reaction to light.

For many manufacturers, lightness testing is an important part of research and development and quality control. However, it is the most difficult test to master. This is because most materials take months or years to respond to sunlight. Testing fabrics under natural light in a real application environment is impossible. Moreover, we cannot say that most research and development departments are willing to wait patiently.

Many manufacturers choose laboratories for testing. They mimic natural light to speed up the testing process. The most successful technique used is the xenon long arc radiation method. This unitary reliable method of mimicking and reproducing the natural light spectrum uses different filters to reproduce specific visual conditions.

Light food testing is not as simple as placing a fabric under a specific light source to monitor its reaction. Both temperature and humidity must be taken into account. This is because both temperature and humidity greatly affect the fabric’s response to light. Therefore, the lightness tester must control these environmental factors, i.e., create appropriate environmental conditions for each test and maintain them consistently throughout the process.

Also, if certain fabrics are used outdoors, mimicking weather factors, especially rain, is another factor to consider. Therefore, the equipment should include a sprinkler system that mimics rainy days and climatic conditions in different parts of the world.

5.2.5 How to improve the lightness of the fabric? Three reliable methods

The mechanism of light dissolution of dyes is very complex. Simply put, it is caused by a series of photochemical reactions that cause the dye to excite after the photon is absorbed and destroy the basic dye structure. It eventually causes discoloration and fading. The lightness of a fabric depends primarily on the chemical structure of the dye and its cumulative state, composition, and color matching. Therefore it is very important to choose the dye logically.

Choose dyes according to fiber properties and fabric applications . For cellulose fiber fabrics, it is advisable to choose dyes with good oxidation resistance; For protein fibers, it is best to choose dyes that have good reducing resistance or weak oxidizing additives. For other fibers, dyes should be selected based on the fading effect. The dye synthesis process can enhance the photocopying resistance of the Aso group within the dye molecular structure. Some powerful electron removal groups are usually introduced at the orthogonal location of the azo group, which reduces the electron cloud ity of the azo nitrogen atom. Also, hydroxyl groups can be introduced at the two orthopedic sites of the Aso group, and its coordinate capability can be used to form complex structures with heavy metals, thereby reducing the electron cloud ity of the hydrogen atoms of the Aso group.

. For cellulose fiber fabrics, it is advisable to choose dyes with good oxidation resistance; For protein fibers, it is best to choose dyes that have good reducing resistance or weak oxidizing additives. For other fibers, dyes should be selected based on the fading effect. The dye synthesis process can enhance the photocopying resistance of the Aso group within the dye molecular structure. Some powerful electron removal groups are usually introduced at the orthogonal location of the azo group, which reduces the electron cloud ity of the azo nitrogen atom. Also, hydroxyl groups can be introduced at the two orthopedic sites of the Aso group, and its coordinate capability can be used to form complex structures with heavy metals, thereby reducing the electron cloud ity of the hydrogen atoms of the Aso group. Dyes should be selected according to color depth. Many experiments have shown that the lightness of reactive dyes on cellulose fibers is directly proportional to the depth of brightness of the dye, i.e., darker, lighter. This is because the higher the dye concentration on the fibers, the greater the accumulation of dye molecules and the smaller the surface area.When in contact with air, moisture and light, the amount of dye is the same and ultimately the dye is less likely to be oxidized by light. In contrast, when the colors are lighter, the dye often dissolves excessively on the fibers. Increases the likelihood of exposure to light, which in turn reduces color speed to light. Therefore, lighter dyes should be used to dye lighter colors. In addition, many finishing agents, such as emollients and anti-corrosion finishing agents, have been added to the fabric, reducing the lightness of the product. Therefore, dyes that are not sensitive to these finishing agents should be selected.

Many experiments have shown that the lightness of reactive dyes on cellulose fibers is directly proportional to the depth of brightness of the dye, i.e., darker, lighter. This is because the higher the dye concentration on the fibers, the greater the accumulation of dye molecules and the smaller the surface area.When in contact with air, moisture and light, the amount of dye is the same and ultimately the dye is less likely to be oxidized by light. In contrast, when the colors are lighter, the dye often dissolves excessively on the fibers. Increases the likelihood of exposure to light, which in turn reduces color speed to light. Therefore, lighter dyes should be used to dye lighter colors. In addition, many finishing agents, such as emollients and anti-corrosion finishing agents, have been added to the fabric, reducing the lightness of the product. Therefore, dyes that are not sensitive to these finishing agents should be selected. Dyes with good light resistance, stability and consistency should be used for color matching. The fading properties and light fading mechanisms of different dyes vary. Sometimes, having one dye makes you feel like another dye is fading. When color matching, dyes should be used that are not sensitive to each other and can improve the stability of the light resistance. This is especially important when painting darker varieties, such as black. One of the three primary colors fades quickly, causing the dyed fibers or fabric to change color quickly. Faded dye impurities will also affect the light stability of the other two dyes that do not fade. For greater lightness, the dyeing process should be reasonably controlled, dyes and fibers should be fully integrated, and hydrolyzed dyes and unmixed dyes should be kept on the fibers as much as possible.

5.2.6 Frequently Asked Questions about the Light Food Test

The lightness of the fabric test equipment is relatively traditional, but it is one of the most important color fast test items.

The lightness testing project is not difficult to implement, but various problems are often encountered in the actual operation process. Here, we analyze common issues in the national standard, ISO and AATCC snack test standards for your reference.

Q1. What is the difference between blue wool 1–8 and L2-L9? Can they replace each other?

Blue Wool Standard Samples 1–8 and L2-L9 in GB / T 8427 and ISO 105 B02 are described in detail. They are all wool and have eight blue label levels, each with a higher number of blue label targets or references that are lighter than the previous number. But different dyes and manufacturing processes are used.

The blue labels are dyed with eight dyes in 1–8 different light foods, making them suitable for the European exposure conditions specified in GB / T8427 and ISO105 B02. For L2-L9, the two fibers are dyed, and then the two dyed fibers are labeled L2-L9 in different proportions. This complies with the US exposure conditions specified in GB / T8427 and ISO 105 B02. It is suitable for AATCCTM 16. However, the blue labels 1–8 and L2-L9 cannot be mixed and the test results cannot be exchanged.

Q2. The lightness tester has the relative humidity of the cabinet. Why do we need to calibrate it with humidity control standards?

Many light testers today can show the relative humidity of the cabinet. However, GB / T 8427 and ISO 105 B02 state that the cabinet humidity must be calibrated daily with standardized humidity control samples. The reason is that the standard sample calibration of moisture control fabrics is not the “relative humidity” of the cabinet but the “effective humidity”. R Applied humidity is also known as absolute humidity. It is defined by the combination of air temperature, sample surface temperature, and relative air humidity, which determine the moisture on the sample surface when exposed. “Effective humidity” Humidity directly affects the test results of the lightness of sensitive samples. It therefore sets the GB and ISO standards for daily cabinet humidity testing.

The humidity control standard is cotton fabric dyed with red azo dye. The method used is as follows:

Place a piece of moisture control cloth (not less than 45 × 10 mm) on a hard cardboard with a standard sample of blue wool in the center of the sample holder as much as possible.

Simultaneously expose the partially covered Humidity Control Standard Sample and the Blue Wool Standard Sample until the color difference between the exposed and undetected parts of the Humidity Control Standard Sample reaches level 4 of the sample card.

In this case, the blue wool standard sample is used to assess the color change of the moisture control fabric and the blue wool standard sample is compliant. The color difference should be similar to grade 5 blue wool. If it does not match, the controller must be reset to maintain the temperature and humidity of the specified blackboard.

Q3. What is the role of xenon reference fabric in AATCCTM 16?

Xenon reference fabric is a purple polyester fabric. Its function is to determine whether the temperature of the box is correct. The method used is to place a xenon probe cloth on the sample holder for continuous exposure for 20 ± 2 hours. If the color difference of the xenon reference fabrics corresponds to the standard sample or if the color measurement with the color difference instrument is CIELAB units 20 ± 1.7, the body temperature of the proof box is normal.

Q4. In some production standards, the 3rd method is required for some light food requirements, and the quality requirement is the intermediate level of 3–4. How should we test it?

Some product standards have such a requirement, and some experts say that this formulation is completely wrong because researchers cannot choose the blue wool standard. However, since some current production standards are specified in this way, it is recommended that operators use method 3 for testing, then refer to method 1 for evaluation. For example, if the standard requirement is 3–4, we choose the 3rd and 3rd blue wool standard to use the requirements specified in Method 4. When grading, 4 and 3 are blue so you can switch to one grading system. Wool standard samples. Theoretically, we can judge whether the test results of the sample reach levels 3–4.

Q5. What is the AFU unit of American AATCC standard? What is the relationship with hours?

AFU is a unit of energy, abbreviated to “AATCC Decaying Unit”. Up to level 1 of the color-changing gray card, the L20 blue wool standard is defined as 4/4 of the exposure energy required to fade. This means that 4 AFU power is required to clear the L4 blue wool standard for color change at level 20. The AFU and radiant energy values ​​for L2-L9 blue wool grade 4 color change are shown in the table below.

When the xenon arc lamp is operated under 1.10W / m2 • nm conditions, the correlation between AFU and hour can be calculated assuming that the energy required to change the L4 level 4 color is 85 kJ / m2.

85 kJ / m2 = 1.10 W / m2 x 3.6 x (hours)

Hours = (85 kJ / m2) / (1.10W / m2x3.6) = 21.5

This shows that as the radiant energy of the xenon lamp changes, so does the number of hours from day to specific AFU. At 1.10 W / m2 • nm the AFU power of 21.5 can be reached in 20 hours only when the lamp is operating.

5.3 Fastness for washing

Laundry is one of the most common cleaning and maintenance methods for clothes. Acceleration of washing colors determines the color stability of fabrics in different detergents and different washing environments. There are many ways to test the speed of color for washing. The general principle is to imitate domestic or commercial washing conditions. Under specific time and temperature conditions, after stirring, washing and drying, compare the original sample using a gray sample card or instrument to assess the color change of the sample and the stains on the lining fabric. Different methods may have some variations in temperature, test solution, washing procedure, drying procedure and whether or not to add steel balls.

5.3.1 Common Fabric Color Comparison Speed ​​Standards:

Chinese Standard: GB / T 3921–2008; GB / T12490–2007

International Standards: ISO 105C10: 2006; ISO105C06: 2010

EU standards: EN ISO 105C10: 2007; ENISO 105C06: 2010

British Standard: BS EN ISO 105C10: 2007; BSEN ISO 105C06: 2010

American Standard: AATCC 61–2010

Australian Standard: AS 2001.4.15–2006

German standard: DIN EN ISO 105C10: 2007; Dinan ISO 105C06: 2010

Japanese Standard: JIS L 0844: 2011

To introduce you to GB / T 3921–2008, for example, “Check the fastness of the fabric color and the fastness of the color soap”.

5.3.2 Color Acceleration Test Process for Soap and Wash:

(1) Model: 100 mm × 40 mm. 100 100 40 mm from the front of the sample. Connect with multi-fiber lining fabric and create a combined pattern along the short side. Or 100 40 mm. Take a sample and measure it 100 40 mm. Sandwich between two single-strand fabrics and sew on the short side to form a combined pattern.

(2) Preparation of the test solution: 5 g of soap per liter of tertiary water is used for A and B tests and 5 g of soap and 2 g of sodium carbonate per liter of tertiary water are used for C, D and E tests respectively.

(3) Test: Place the combined sample and the specified number of steel balls in the container according to standard test conditions. Inject the required soap solution heated before the test temperature ± 2 to, then the bath ratio is 50: 1. Close the container, adjust the temperature and time to the standard and start the machine. Remember to start the time when the container is closed.

(4) Washing and drying: For all tests, after washing, remove the combined samples, rinse twice with tertiary water, and then rinse with water until they are clean. Squeeze excess water from the combined sample by hand, flatten the sample between two unused filter paper to remove excess water, and then hang it to air dry at a temperature not exceeding 60 C. The sample is related only to the location of the reference.

(5) Grading: Use a gray sample card or instrument to compare the original sample and assess the color of the sample and the stains on the lining fabric.

(6) Preliminary report

5.3.3 Analyze the reasons for improperly checking color fastness for laundry

The texture of the fabric, the composition of the fibers and the corresponding dye processing conditions are the main factors influencing the rapid washing of the fabric. In general, the color of single-component fabrics is better than blended fabrics. All polyester, cotton, nylon and all wool fabrics have a lower risk of color problems. Dyes are selected to match the fabric components. They can usually be obtained in grades 3–4 or more after processing at the dyeing factory. Level 4 is easily accessible as the color cleansing and healing and other processes are properly controlled.

For blended fabrics, the post-dye wash color speed is generally lower than that of the corresponding single-component fabrics, especially when the dyeing process is improperly controlled. For example, when dyeing polyester-spandex composite fabrics in dark colors such as black and red, the wash color fastness often fails.

The use of dissolved dyes (a type of non-polar, non-ionic dye that relies on dispersing agents to spread the color of synthetic fabrics) to dye polyester fibers usually stains the spandex severely. When choosing a dispersion dye, it is important to consider whether they have good dye properties and, at the same time, to ensure that the stain removal of Spandex is relatively easy.

Some dye factories in Xiaozhou, in a one-sided production, often use high temperatures to quickly shape the finished product. But when the temperature is high, the dye molecules can easily escape from the polyester molecular structure. The various surface act species on the fiber surface accelerate this process and as a result, the surface of the finished product appears floating in color. For dissolved dyes such as polyester, nylon, acetate, and spandex dyes, the heat transfer phenomenon is an important factor in accelerating the unsatisfactory color of these fabrics and excessive staining of the acetate lining and nylon lining. The heat transfer of the dispersed dye penetrates into the fiber surface and penetrates into the fiber surface. The deeper the dyeing depth and the more pronounced the above phenomenon as the post-processing temperature increases. After dyeing, It is important to reduce the cleaning treatment to remove the floating paint on the surface of the dye and polyester contaminated by the Spandex component. Currently, polyester-spandex blended laundry detergent can be increased to level 4 by reducing the acid with thyroxine dioxide or by cleaning with sodium hydroxide and soda ash, thereby meeting the high-end brand clothing requirements.

Nylon, silk, and wool blends often experience poor washing speed in real manufacturing and life processes. Similar to protein fibers such as nylon silk and wool. Acid dyes are commonly used for dyeing because they contain some amino and carboxyle groups in their molecular structure. As a water-soluble dye, acid dyes have a small molecular weight, resulting in acid dyes being used as a result of a wet treatment acceleration test on poorly dyed fibers, especially for faster washing. Dye dissolution is relative to the water solubility of the dye molecule. The sulfonic acid group in dyes binds to fibers by hydrogen bonding. When the dyed fabric is immersed in water, the hydrogen bond is cut off, and part of the swollen dye is removed from the fibers and dissolved in water. When the dyed material is mixed in the washing machine, Upon mixing, the insoluble dye pigment will fall off the fibers. The higher the washing temperature, the larger the bathing rate, and the longer the stirring, the greater the dyeing. In addition, the presence of the surface material during the washing process greatly increases the dissolution of the dye from the fibers. The main reason for dye removal is the lipophilicity of the pigment molecules, which can disperse with the hydrophobic base of the surface actin, thereby pulling the dye away from the fibers. To increase the washing speed of acid dyes, we must first select dyes with large dye molecules and several water solubility groups to limit the mechanical movement of the dye in the fibers and increase the bond between the dye matrix and the fiber strength. Also, the tannin method and the artificial fixing method can be used, and the fabric is fixed after dyeing.

The use of different test methods, washing the same connections in different test modes and operating modes also has an important effect on the color acceleration test results. At present, standards have been approved and implemented to speed up the color of local and foreign laundry. These standards have been revised and improved many times, including the European standard ISO 105 C10: 2006, the national standard GB / T 3921–2008 and the American standard AATCC 61: 2013. However, the test methodology is basically the same as the test principle, but the test conditions are different. The general washing quality parameters are given in Table 1.

Table 1 shows that the test conditions of the European standard and the national standard are the same. In contrast, the American standard differs greatly from the European standard and the national standard in that the addition of steel balls, the detergent used and the washing time all eventually lead to different test results. In the early stages of the experiment, two samples of dark coffee and dark wine red knit fabrics were used, as well as two samples of blue denim and white and black striped fabrics. Furthermore, the European standard, the national standard and the American standard were used, respectively. The same line conditions were tested, and then the test sample was determined to be color fast for washing. The test results show that there is a slight difference between the test results in the national standard and the European standard, but there is a big difference between the two and the American standard. In terms of color change, the color difference between the national standard and the European standard is lighter, and both generally have a grade of 0.5 higher than the American standard. In terms of staining, the national standard and standard European colors are heavier and their staining grades are generally 0.5 times lower than the standard American level.

Color rapid testing for laboratory washing involves a variety of procedures: sampling, lining, washing test, drying, grading. Although it is the same test method and the same test parameters, different testers are subject to their own habits, subjective judgments, and other human factors. The effect of the test results will also lead to some changes in the test results, so each link must be functional in accordance with standard and integrated specifications. Otherwise, it will affect the color acceleration results to some extent.

Effect of sampling on test result results for color acceleration for washing : According to GB / T 3921–2008, when the sample is fabricated, the sample size is 40mm × 100mm. However, most of the laboratory daily test samples are divided into simple, yarn dyed, printed and dyed fabrics. Accurate extraction of agent samples will have a greater impact on test results within a specified quantity. Dye samples in dark and light patterns have a natural transition from multiple colors and gradually the colors change from dark to light or from light to dark. When sampling, avoid the place where the color is present and cut two test samples in light and dark places evenly dyed. If the color of the sample site is not uniform, it will easily affect the test results and is not representative. Effect of multi-fiber standard lining fabric selection on test acceleration test results:In the GB / T 3921–2008 standard, the choice of lining fabric can be two or more fiber lining fabrics, but the final test is more convenient. Multi-fiber interwoven fabrics include DW type (multi-fiber interwoven fabric containing wool and acetate) and TV type (multi-fiber interwoven fabric without wool and acetate). In the selection of multi-fiber lining fabrics, the national standard GB / T 7568.7–2008 “Speed ​​Testing Standard for Fabric Color Fabrics Part 7: Multi-Fiber” General Requirements: Wool and acetate may not be used for rapid testing of certain colors. Also, when using fiber, the TV type should be used instead of the DW type. However, the expression of “certain color fast tests” is somewhat ambiguous. The national standard GB / T 3921–2008 does not specify test conditions, which may result in the use of different multi-fiber standard fabrics and vary in the results obtained. Choose from 23 randomly woven fabrics and samples of different fiber components. According to the C (2008) method of the national standard GB / T 3–3921, cut two samples from them and compare them with DW type and TV type multi-fiber. Sticking a standard sample to a combined sample for testing, the test results show that most samples use DW-type multi-fiber standard line fabric rather than a TV type test. The results are lower and the staining grade of acrylic single fiber strips and polyester, nylon and cotton is 0.5 to 1 lower than DW type TVs. Choose from 23 randomly woven fabrics and samples of different fiber components. According to the C (2008) method of the national standard GB / T 3–3921, cut two samples from them and compare them with DW type and TV type multi-fiber. Sticking a standard sample to a combined sample for testing, the test results show that most samples use DW-type multi-fiber standard line fabric rather than a TV type test. The results are lower and the staining grade of acrylic single fiber strips and polyester, nylon and cotton is 0.5 to 1 lower than DW type TVs. Choose from 23 randomly woven fabrics and samples of different fiber components. According to the C (2008) method of the national standard GB / T 3–3921, cut two samples from them and compare them with DW type and TV type multi-fiber. Sticking a standard sample to a combined sample for testing, the test results show that most samples use DW-type multi-fiber standard line fabric rather than a TV type test. The results are lower and the staining grade of acrylic single fiber strips and polyester, nylon and cotton is 0.5 to 1 lower than DW type TVs. Test results show that most samples use DW-type multi-fiber standard line fabric rather than TV type test. The results are lower and the staining grade of acrylic single fiber strips and polyester, nylon and cotton is 0.5 to 1 lower than DW type TVs. Test results show that most samples use DW type multi-fiber standard line fabric rather than TV type test. The results are lower and the staining grade of acrylic single fiber strips and polyester, nylon and cotton is 0.5 to 1 lower than DW type TVs. Effect of different grading methods on test result results for color acceleration for washing: Color speed can be graded by eye or device. Neutral gray background is required for optical grading, sunlight and daylight (9: 00–15: 00) or similar light sources with 600lx and above. The incident light should form an angle of about 45˚ with the fabric surface. The optimal observation direction is perpendicular to the fabric surface. Further, the color of the cover plate covering the original sample and the sample after the test should be the same size and shape. The grader should wear neutral gray clothing and avoid environmental color effects during the grading process. At the same time, have a clear understanding of the standards relevant to the grade, be familiar with the standard requirements and relevant regulations of the enterprise, and accurately assess the grade of the combined sample. However, due to differences in perspective between different assessors, Rating results will be significantly affected. Therefore, it is necessary to compare the differences in view over time. This is how some human error can cause enterprises and customers unnecessary losses.

Under normal conditions, weakly colored fabrics can be washed, rinsed, and unpainted to prevent staining. In general, the speed of color greatly affects the washing of fibrous pores and floating paint remaining on the surface. A good washing process and the corresponding cleaning agents can completely remove unmixed dyes. For fabrics that have been dyed with direct, reactive, and acid dyes, the color fastness of the fabric can be improved after the fabric has been cleaned, with the corresponding reactive fixing and acid fixing processes. The dye mass absorbed in the fabric or yarn is divided by the original dye mass in the water bath.

5.3.4 Summary of sampling methods for color acceleration for washing:

Large-scale testing institutes generally follow a process-based approach to color sampling tests, which are generally divided into sampling positions, test positions, and grading positions. Therefore, although it is the same test method, different testers are influenced by the practice and subjective judgment of the sampling methods and make some differences in the test results.

Fast sampling of colors for laundry should be considered first. GB / T 3921–2008 For example, this standard specifies that the choice of lining fabric can be a multi-fiber lining fabric or two single fiber lining fabrics.

Multi-fiber lining fabrics include:

(1) Multi-fiber lining fabric containing wool and cellulose acetate (used for 40 ° C and 50 ° C tests and in some cases at 60 ° C but should be mentioned in the test report).

(2) Wool and acetate-free multi-fiber lining fabric (used for 60 ° C tests and all 95 ° C tests). Cotton, wool, viscose, polyamide (nylon), polyester (polyester), polyacrylonitrile (acrylic), rum, silk and acetate are among the single fiber fabrics.

Taking the multi-fiber lining fabric test as an example, the sample methods of the different types of samples in the washing acceleration test are analyzed in detail.

Laboratory daily test samples are roughly divided into simple samples, yarn dye samples, print samples, dark and light grade dye samples, embroidery and car pattern samples, sequins, hot diamond samples, thread and loose fibers, hollow fabrics, and more. For GB / T 3921–2008 the sample should be fabric, sample size is 40mm 100mm.

Simple color samples

Depending on the standard requirements for the sample size, the sample is randomly cut along the type or fabric direction in front of the fabric. But the sample should be taken from a large sample of evenly dyed, wrinkle-free and group dyes. The distance from the edge of the fabric should not be less than 10 cm so that stable results can be obtained under the entire working surface during the test.

Thread dye samples

According to the standard for sample size, the sample should contain all the colors of the sample. Suppose a sample does not contain all the colors in the sample. In such a case the sample size can be determined in proportion to each color in the sample and the darker part is more appropriate, or the number of samples obtained can be increased but usually not more than three sample sets.

Printing of samples

Rich colors characterize this type of product. Printed samples include small prints, large prints, and intercolor lines. The basic principle of sampling is to follow the excavation method to take all the colors and focus on keeping the same color parts around the sample as the original sample for grading. Comparison at excavation. If a sample does not contain all the colors, you can increase the number of copies or prioritize the darker color test by determining the sample size in proportion to each color. The following is a detailed analysis of the various samples.

Single circle small print

When sampling a single cycle on a small print, try to ensure that the sample has a complete print sample. Sometimes, the same pattern printing also causes some color change due to the effect of the color paste prescription, printing process and fabric structure. The sample should be taken from the excavation. When excavating, keep the same color around the sample as the original sample for grading comparison after the test.

Circ circulates on the ground and there are no irregular small prints

This type of sample has rich colors. Before sampling, you must first observe the sample and select a representative agent with a uniform dye to select the sample. Often, one sample may not contain all the colors, so the number of samples should be increased.

Large print without circulating circulation

Among the samples submitted by customers for testing, such as quilts and quilts, these samples are characterized by relatively large margins and relatively large prints. In this type of sample, the color of each flower varies. In general, a sample cannot cover all colors. In this case, it is necessary to select the sample in a relatively dark place. Moreover, it is necessary to consider the ratio of the dark and light samples of each color to a specific ratio. The dark location alone is not available as dark and light color transitions may occur during the test. Therefore, not only the staining of the sample but also the color of the sample should be considered when sampling.

Circ Large round print

This type of sample is usually rich in color but is cyclical. Take a sample of one of the loop patterns. Also, if there are no other colors, consider increasing the number of samples.

⑤ Inter-color strip printing sample

The color of all the columns should be included in the sample within the specified sample size. Color Acceleration Soaping is a rolling test and there is no specific pressure requirement as the color fastness varies from sweat to static test. When sampling, it is not necessary to sample in the direction of the column until all the colors have been added. Suppose a sample cannot contain all colors. In such a case, you can increase the number of copies or determine the sample size in proportion to each color, and take precedence over the relatively dark part for testing.

5.4 Testing of heat dissipation (dry heat) of fabrics

5.4.1 Comparison of major test methods for thermal pressure and color acceleration for fabric ironing:

The operating procedure of the three standard test modes is approximately the same. The preparation tools are as follows:

5.4.2 Take, for example, the AATCC color fast test method:

This test method is a test method for determining the color resistance of various fabric materials and fabrics and the ability to process heat resistant rollers.

The fabric can be subjected to hot media tests in dry, wet and damp conditions.

Testing process:

Sample Size:

AATCC 133–2009: 40 * 120mm (Sample size for other test methods: 40 * 100mm)

Heating device:

It consists of a pair of smooth parallel plates with a precise control electric heating system. Sample pressure is 4 ± 1kpa. The heat should only be transferred from the upper parallel plate to the sample. The bottom parallel plate should always be covered with asbestos sheet, whether heated or not. The M2 double-layer synthesis contains about 3 mm of wool flannel, unbroken and bleached cotton fabric without suppressing the reaction.

Testing procedure

Dry Compression: The dry sample is pressed in a heating device at a specific temperature and pressure for 15 seconds.

Tidal Pressure: After the dry sample is covered with a damp cotton cloth, it is pressed for a specified period of 15 seconds in a heated device at a certain temperature and pressure.

Wet compression: After the wet sample is covered with a damp cotton cloth, it is pressed for 15 seconds in a heated device under a certain temperature and pressure.

Hot pressure temperature

110 ± 2

150 ± 2

200 ± 2

If necessary, different test temperatures can be used but they should be noted in the report. The critical temperature is determined by the type of fiber and the fabric structure. If it is a blended product, it is recommended to adapt it to more heat resistant fibers.

Credit rating

Immediately after the test, use gray to assess the color change in the sample and the stains on the lining fabric. Perform another assessment 4 hours after controlling the standard atmospheric humidity.

5.4.3 Iron Tips for Everyday Life:

Before ironing clothes, pay attention to the fabric characteristics of the clothes, because some fabrics are not resistant to high temperatures and others are not. For example, natural fibers such as silk and wool are not suitable for high-temperature irons, and fabrics such as cotton and linen. For some special fabrics, it is advisable to iron directly on the fabric surface and the fabric will be shiny and white. In this case, all you need is an iron covering the surface of the fabric with a piece of cloth or cloth with the same texture. It does not show in this case. Before placing the iron, it is best to spray the mist evenly with water from a sprayer and put the clothes in a plastic bag so that the moisture can spread evenly. Iron clothes can be hung in a ventilated place and the clothes can be kept flat and powdered to allow water vapor to evaporate for a while.

5.5 Color acceleration for sweat

As we all know, the composition of human sweat is complex and its main component is salt, the amount of which varies from person to person. Sweat is acidic and alkaline. The short-term contact between the fabric and the sweat will not have as much effect on its color fastness, but the long-term contact with the skin and sweat will have a greater effect on certain dyes. Inappropriately colored clothing can lead to the transition of sweat from dyed fabrics to human skin through fasting. The human body can absorb dye molecules and heavy metal ions through the skin, which can be dangerous to health.

5.5.1 Comparison of test methods for color acceleration with perspiration

5.5.2 Examples of test methods for fabric sweat resistance

Use synthetic sweat to mimic the sweating condition to test the fabric.

First, cut 4mmX10mm test samples to a specific millimeter according to project requirements, then sew the line according to the sample type, then place them on a plate as shown in the figure below:

Then add freshly prepared sweat stain solution (Fig. 3, Fig. 4) and soak for 30 minutes (Fig. 5) (human sweat has a complex composition, sweat is acidic and alkaline and some of the dyes in the fabric are not acid-resistant and some are not. Not alkali-resistant. Under the same conditions, artificial perspiration with different acid and alkali levels should be tested separately).

Once the soaking is complete, take it out and remove the excess sweat and sandwich between the two sample plates. Use the same procedure to combine the samples and stack them together. After stacking them, place them between the sweat rack and the spring pressure plate, place a load on the spring pressure plate (as shown in Figure 6), remove it, pour in excess sweat and form a joint test body.

Place the combined test body in a constant temperature oven for some time (Figure 7).

Once it is removed, use a dull / stained gray card to assess the color of the sample and the staining of the lining fabric (Figure 8).

5.5.3 How to improve color speed up to sweat? Examples of techniques for color enhancement Nylon fabric accelerates to sweat

Weak acid dyes are widely used for nylon printing and dyeing. It is important to note that dyes and fibers are mainly combined with van der Waals forces and hydrogen bonds, resulting in weak color fastness. Although commercially available acid dye fixing agents can improve color fastness with soap and scrub, it is still not an effective sweat accelerator. Although adequate soaps, dye selection, optimization of the fixing process, and new fixing agents or accelerators can improve the color fastness for acidic sweat, the color fastness for alkaline sweat is still poor.

Improving the color fastness of acid dyes is still primarily a polyamide fixing agent, which is a square ammonium salt. The polyamine compound and the disandiamide polycondensation reaction are often used to form the formaldehyde-free polyamide mounting agent. Although the square ammonium salt type polyamide fixing agent can significantly improve the fastness of acid dyes, it reduces the fastness of the fabric.

The purpose of this research is not to reduce the color acceleration by rubbing, but to accelerate the color up to the corresponding square ammonium salt polyamide fixing agent sweat. The test first measured the color-fixing effect of the sweat-accelerating agent SF-30A and then the accelerating agent SF-30A and the wet acoustic magnifier HS-222, the adhesive SD-20B and the acrylate monomer detailed treatment for nylon enhanced colors. Investigated the impact. Faster to rub and faster to color for printed fabric sweat.

Experimental part

1.1 Materials

Fabric 380T nylon spun printed fabric, 20D / 20D, overall dens quality 35g / m2.

Sweat accelerators SF-30A (square ammonium salt polyamide, 30% content, self-made), adhesive SD-20B (copolymer of butyl acrylate and acrylic acid monomers, content 24%, homemade), wet HS-Industrial grade, chemical agents FMEE, ammonium persulfate and other additives.

1.2 Test method

1.2.1 Completion Process

(1) Process flow

Nylon Fabric → Impregnated Liquid → Centrifugal Dehydration → Drying → High Temperature Baking → Finished Product

(2) Liquid prescription termination /% (omf)

Sweat accelerating agent SF-30A x

Wet vision enhancer HS-222 y

Glue SD-20B z

(3) Classification conditions

pH 4.5 ~ 5.5 (prepared by acetic acid), bath ratio 1:20, immersion for 20 minutes at room temperature and bake at 160 C for 3 minutes.

1.2.2 Padding Finishing Process

(1) Process flow

Nylon fabric → Padding finishing liquid ‍ Drying → High temperature steam උෂ්ණත්ව Drying → Finished product

(2) Monomer emulsion

Mix 3% acrylate monomer, 0.75% emulsifier FMEE and 0.15% ammonium persulfate for high shear emulsion. Emulsion time for preparation of monomer emulsion is 30 minutes.

(3) The composition of the finishing fluid

Add 4% sweat accelerating agent SF-30A to the above monomer emulsion, and set the pH to 4.5–5.5 with acetic acid.

(4) Classification conditions

Room temperature, double immersion and two rolling, rolling speed 90%; High temperature steam, humidity 40%, temperature 160 ℃, time 5 minutes.

1.3 Test method

(1) Accelerate color by rubbing

Check according to GB / T3920–2008 “Fabric color fastness testing by color fastening” and according to GB / T251–2008 “Fabric color fast test gray for staining evaluation”.

(2) Acceleration of perspiration

According to GB / T3922–2013, GB / T251–2008 “Fabric color fastness testing staining gray” According to the ratings, “Fabric color fastness testing is color fast.”

Results and discussion

2.1 Effect of perspiration accelerator on the color fastness of nylon

Nylon printing fabrics follow the embedding finishing procedure of Section 1.2.1. The mass fraction of sweat accelerating agents SF-30A for color acceleration is given in Table 1.

Table 1 Effect of mass fraction of sweat accelerating agent SF-30A on color fastness.

Table 1 shows that nylon print fabrics are excellent for excellent dry and wet rubbing and wool staining, but the acceleration to nylon alkaline perspiration is weak; Grade 2 to 3 only. After finishing with the sweat accelerating agent SF-30A, dry rubbing accelerates and has no effect on alkaline perspiration. The color of the fur is fast and it is still 4 ~ 5. However, it has a clear improvement over alkaline sweat rapid nylon staining and increases with increasing mass fraction of SF-30A. The maximum value can be increased from 1.5 to 4, but it causes a decrease in the wet rubbing speed in the weave and weave directions, and a decrease in the wet rubbing speed with the SF-30A finishing agent is related to the SF size. -30 a. When the mass fraction of the SF-30A is 4%, the wet rubber velocity will drop by a maximum of two levels. This is because the SF-30A finishing agent is a cation polyamide square ammonium salt that has good contact with nylon and anionic acid dyes and can form a film on the fiber surface. It also has a good color speed for alkaline perspiration. Therefore, nylon staining can improve sweat acceleration, while dry rubbing does not affect speed and alkaline sweat does not affect the speed of wool. Electrostatic interactions between cationic polyamide and acid dyes can reduce the acid dye resolution on fabrics in an alkaline medium. Still, when it gets wet, the acid dye causes the fibers to migrate to the surface, i.e., it improves the speed of the acid dye for perspiration and slows down the wet rubbing. The acid dyes used for textile printing have excellent alkaline perspiration.

2.2 Effect of antiperspirant and moisturizer

The finishing process of Section 1.2.1 is followed to improve the fastness of nylon printed fabrics treated with Sweat Acceleration Agent SF-30A. The total mass fraction of the fixed finishing agent is 8%. The sweat accelerating agent is SF-30A. Amplifiers HS-222 were mixed at different mass ratios, and the effect of the two mass ratios on the color acceleration of the fabric on corrosion and perspiration was investigated (Table 2).

Table 2 Effect of mass ratio of sweat accelerating agent SF-30A and wet grinding enhancer HS-222 to accelerate the color of fabrics

Table 222 shows that the sweep accelerators SF-2A and the wet-enhancement agent HS-30 used for the same bath affect the wool staining and dry rubbing speed of nylon printed fabrics; It accelerates alkaline perspiration and increases the level of nylon staining to 2 levels; But the wet rubber speed is still down to 1.5 levels. A comparison of Tables 1 and 2 shows that when the amount of sweat accelerating agent SF-30A is the same, the addition of a moisturizing enhancer HS-222 may be useful to improve the alkaline perspiration rate, but not to improve the wet detection speed . This may be due to the fact that HS-222, which has cross-linking membrane-forming properties, can enhance the interaction between polyamide cation square ammonium salts and fibers, enhancing the fastness of the fixing agent to alkaline perspiration. However,

2.3 Effect of perspiration accelerator and adhesives

Sweat Acceleration Agent SF-30A and nylon fibers follow the finishing process of Section 1.2.1 to improve the acceleration speed and the total mass fraction of the static finishing agent is 8%. Sweat accelerating agent SF-30A and adhesive SD-20B were mixed at different fast mass ratios to detect color acceleration and color acceleration up to sweat on color acceleration. See Table 3.

Table 3 Effect of mass ratio of fast perspiration agents SF-30A and adhesive SD-20B on fabrics Color acceleration

Table 20 shows that the use of SF-3A and adhesive SD-30B, the sweat accelerating agents in the same bath, does not affect the alkaline perspiration of wool stains and the dry rubbing speed of nylon printed fabrics; It does not affect the speed of nylon staining for alkaline sweat. Color acceleration can be improved by 1.5 grades and the effect on wet rubbing speed is small. When the mass fraction of adhesive SD-20B reaches 6%, the wet rubbing speed does not decrease. This is due to the electrostatic effect of the anionic SD-20B and cationic SF-30A, which bind rapidly to the fibers of the finishing agent, preventing the transition of the acid dye to the surface in the wet state, and ultimately enhancing the resistance of the finishing agent. Alkali and sweat. However, it is relatively easy to assemble and create a permanent stain during use. For this reason, Although the use of non-ionic surfactants for the addition of O emulsification is useful to prevent accumulation, it is not good for alkaline perspiration to improve the color fastness of nylon. Therefore, this method is worth discussing further.

2.4 Effect of micro polymerization on acrylic monomers

Acrylic adhesives are effective in accelerating perspiration and slowing down the wet rubbing of nylon printed fabrics. Therefore, an emulsion of 18 acrylic monomers was selected for finishing in the same bath with sweat accelerating agent SF-30A (Section Padding Finishing Process) in the same bath. And the fastness of the fabric. The results are shown in Table 4.

Table 4 Effect of acrylate monomer polymerization on color acceleration of fabrics

Table 1 shows the polymerization of acrylic monomers, (30) the speed of dry rubbing and the speed of alkaline sweat wool staining, compared to the unfinished or single-sweat accelerating agent SF-4A. -MA, TMPTMA, PEG200DMA, PEG400DMA, TMP3EOTA, DEGDMA, TEGDMA) decreases by 0.5 and the color speed of other monomers remains unchanged;

(2) the staining speed of alkaline sweat nylon improves by 1.5 to 2.0 grades over unfinished fabrics and by 1.0 to 30 grades over SF-0.5A finish;

(3) Wet rubbing speed is 0.5 ~ 2.0 lower than unfinished fabric. With the exception of some monomers (PHEMA, PEG400DMA and Di-TMPTA), the reduction is smaller than the SF-30A finish;

. Wet rubbing speed decreases slightly and reaches 4th grade.

Acrylic monomers can self-polymerize under the action of beginners to form a film on the fiber surface. Still, the nature of the film or the interaction with the sweat accelerating agent SF-30A and the fiber affects the color speed. Because:

1) When the finishing agent SF-30A stands alone, its mounting mechanism depends on the ionic binding and film-producing properties. When the fiber surface finishing agent SF-30A film is formed, it has better alkali resistance and can prevent the dye from becoming an alkaline medium. Analysis, reducing fiber re-staining (staining), improving the speed for alkaline perspiration and improving the speed of dry rubbing. However, when the film made by the finishing agent has good swelling properties, it accelerates the dye resolution by wet rubbing and reduces the speed of wet rubbing.

2) The structure of acrylate monomers contains vinyl groups and the polymerization reaction takes place under the initiation of ammonium persulfate. Acrylates can be polymerized into individual polymers and can interact with fibers, finishing agents SF-30A, etc. Therefore, the graft copolymerization of acrylic monomers on fibers acts as a cross-linking agent.

3) Due to the copolymerization of the acrylate graft, the properties of the finishing agent SF-30A and the fastness to the fibers change. This is related to the properties of acrylate monomers such as the D-TMPTA monomer with four vinyl groups and the BPA2 EODMA monomer with the bisphenol-A structure. They can be increased by increasing the reactivity of the monomer or by introducing the structure of the benzene ring. It improves the speed of alkaline perspiration and can be maintained with excellent dry and wet rubbing.

Effect of monomers and color fast additives on the fastness of nylon fabrics for perspiration:

(1) Cationic sweat accelerating agent SF-30A can improve the speed of acid dyes but also reduce the speed of dyes. When the SF-30A and HI-222 HS-222, which accelerate sweating in the same bath, are finished, the detection speed of nylon printed fabrics can be reduced.

(2) The cationic sweat accelerating agent SF-30A and the anionic binder SD-20B are treated in the same bath, which not only improves the speed of the acid dyes but also reduces the speed of the nylon printed fabric. There is a tendency to add inadequately.

(3) Polymerization of acrylate monomers is useful for enhancing the acceleration rate but it is related to the self-polymer properties of the monomer. When selected with a D-TMPA monomer or bisphenol-A structure and sweat accelerating agent SF-2A with four groups of vinyl in the same bath, nylon printed fabric has the perfect color fastness and alkaline perspiration. The color fast degree is 30 4, and the rubbing speed is up to 5.

Part 3

Poor colors in the text get faster

6. How to speed up the color of fabrics (general rules)

The dyeing speed of fabrics is related to the fiber, yarn structure, fabric structure, printing and dyeing method, dye type, and external force.

The following are general principles for improving the color fastness of fabrics. With regard to single color fastness, there are targeted enhancement methods.

Start with the following three sections:

6.1 Selection of dyes

How fast a product is made depends heavily on the choice of dye. If the choice of dye material is inappropriate, there is no way to quickly dye high quality colors, no matter how good the auxiliary agent and the best dyeing process. Only by choosing the right dye can we talk about the next step.

(1) Select the dye according to the fiber characteristics. Different types of dyes and fibers have different types of bonds and the strength of the bonds also varies. Once you have determined the type of dye, choose a dye with a high degree of dye. For example, when dyeing wool fabrics, they are strong acid dyes. Locally produced strong acid dyes are not as good as imported strong acid dyes. Not only are the earlier ones not as good in color, but their binding strength is not as good as the second. Different dyes have different bonding speeds to the wool and dye the variegation. For example, wool yarns dyed from weak acid dyes are faster in color than strong acid dyes. In the case of pure cotton or renewable cellulose fiber fabrics, direct dyes (a type of dye applied directly to cellulosic fabrics) or reactive dyes (a dye group are considered the most permanent dyes because of their adhesive nature. Can be used for fabric fibers and to form covalent bonds). In addition to acid dyes and some reactive dyes, individual direct dyes can also be used.

(2) Select the dye according to the color depth. After determining the type of dye, it is necessary to further determine which dye should be used depending on the color scheme and depth of the dye. Try to choose shades that are close to the desired color. If there is a deviation, use other dyes to color. Second, look at the color speed index of the selected dyes. If the color fastness of the dye is poor, the process can increase the color fastness by half. Finally, see if the saturation of the dyes can reach the desired color depth. Although the desired high depth color is temporarily available after processing, choose a dye with a very low dye ratio. The dye combination is not permanent and will break down when reused.

(3) Select the dye according to its color fastest grade. With the introduction of each dye, the color rapid range of the dyes is also introduced. When choosing a dye type, you should choose the dye according to the color fastness range required for the product, and the dye speed of the matching color dye should be the same. For example, the color fastness of dyes can only reach 2 ~ 3 or 1 ~ 2, no matter how good the auxiliary and dyeing process is, a product with 4 ~ 5 color fastness cannot be dyed. The color fastness of dyes depends mainly on the bonding strength between the dye and the fiber, and if the bond between the two is not strong enough, they cannot be permanently bonded to an external force even if the color is enhanced. They also do not tolerate damage from external factors such as washing and decontamination.

(4) Speed ​​of dye extraction in fibers. Different dyes show different dye obtaining rates and the rate of obtaining the same dye dye also varies under different dye dye conditions. Therefore, the dyeing ratio should be considered when choosing a dye. Otherwise there will be competition between the dyes. One type of dye captures the dyeing area in advance, while the other dye can be applied to the fiber surface and not evenly. It forms a strong bond with the fiber, which is destroyed first in the subsequent process or in daily use. This is why some colors fade and show a completely different color system than the original color. Therefore, when selecting dyes, dyes with the same dyeing speed should be selected under the same conditions, which is also very useful for the next step in the processing process.

(5) There should be good consistency between the dyes. Different dyes in the same fabric have different consistency — the greater the compatibility value, the better the color matching ability of the dyes. There should be good consistency between the dyes to match the colors. For colors that are not easy to fight, it is best to use the three primary colors. The three primary colors have the best match between each type of dye and are the three dyes with the most complete and most positive color matching. Therefore, it is best to use the three primary colors to match some of the more difficult, weird colors and try not to use other dyes to fight. It tends to compete with flower dyeing and dyeing. 2.1.6 To minimize the number of dyes required, first select dyes that are similar in color to the desired dye, then use one or two dyes to eliminate the shadows of the main dyes. For dyes of the same color range, The color dyed in this way should be clean, smooth, elegant and full. Try not to use four or five dyes for coloring, it is not easy to color and great dyes are not easy to handle. Furthermore, even if the color and brightness match, the dyed shade is not bright and complete and cannot be fully integrated with the dye fibers, and its contrast color is a weak color fastener.

6.2 Selection and use of additives

(1) Select the appropriate additives. After determining the type of dye, the choice of additives is also very important. In general, try to choose an auxiliary agent that is compatible with the dye; If it is a commonly used dye, the amount of auxiliary agent should be determined and the method of use should be emphasized. For darker colors, the dye is not easy to get tired of. The auxiliary agent can be added in groups to increase the wear rate and improve the speed of dye absorption to play a role in color fixing.

(2) Minimize the amount of regression. The amount of regenerating agent that plays the role of dye dye should be minimized. Otherwise, it has an unwanted effect of removal. On the one hand, it will reduce the dye intake, and on the other hand, it will weaken the dye binding force and fibers, thereby worsening the color fastness. For colors that are easy to dye, the leveling effect can be achieved by applying the dye and warming up.

(3) Selection of mounting agent. Using a fixing agent will usually improve the color fastness of the paint at least 0.5 ~ 1 level, but the choice of fixing agent should also be based on the speed of the paint over the individual items. For example, after treatment with reactive dye cations with low molecular weight or polymerization type fixing agents, the washing speed is 4 ~ 5 but the lightness is lower. Also, during mounting, the size, temperature, and mounting time of the mounting agent should be strictly controlled.

(4) Soap and wash. When washing with soap, you should wash thoroughly and pay attention to the washing temperature and time. Otherwise the floating color on the fabric surface will fade with use.

(5) Use of emollients. A softener needs to be added to make the product smooth and soft. The softener classifications are cationic, anionic, nonionic and silicon. The final process after the dyeing process is softening. The dye and softener further react, while the acid dye with an organic silicone softener reduces the color fastness. Some dyes are removed during the softening process. To lighten the color a bit. Therefore, the amount of emollient used for emollient treatment must be accurate; Otherwise, it feels sticky and affects the dyeing.

6.3 Next Improve the dyeing and finishing process

Completely reduce the stalk portion of the fibrous macromolecular structure and increase the stiffness of the non-crystalline region. The stiffness of the different regions in the fiber is consistent. This is so that the combination of fibers is more uniform once it enters the dye fibers.

This can not only improve the level of dyeing, but also improve the speed of exposure to sunlight. If the stiffness of the different parts in the fibers is not sufficiently balanced, most dyes will remain in the region with a relatively loose structure. After the extreme conditions of the exterior, the dye will more easily separate from the inner area of ​​the fibers and absorb into the fabric surface, thereby reducing the fastness of the fabric.

Dissolving and blending cotton fabrics and pre-shrinking and resizing polyester fabrics is a processing process that balances the stiffness of the fibers. After washing and tasting cotton fabrics and pre-shrunk and pre-shaped polyester fabrics, the depth and color speed of the dye can be significantly improved.

Strengthening the post-treatment and washing and removing floating dyes on the surface can also significantly improve the speed of the fabric. Appropriate lowering of the specified temperature during the processing can significantly improve the speed of the fabric. Reduced fabric stability due to cooling can be compensated by properly reducing the processing speed. When choosing finishing agents, attention should also be paid to the effect of additives on color fastness. For example, after the use of cationic softeners to soften the polyester fabric, the rapid acceleration test of the dissolved dyes may fail due to the heat transfer of the dissolved dyes. From the temperature point of view of dispersed dyes, they have a much faster velocity than high temperature dispersing dyes.

to sum up:

Many factors affect the speed of dyeing fabrics. For internal factors, all manufacturing processes are operational to ensure that the product can have excellent color fast indicators to meet daily use and reprocessing requirements; For external factors, we should pay attention to the washing temperature, detergent and laundry detergent, determination strength, exposure time and other factors that can reduce the color fastness of the product, then the product can be used better.

Section 4

Knowledge of textile color fastness

7. Common questionnaire to test color fastness

Q1. When the spinning product standard does not specify the requirements for the test sample, is the horizontal rating evaluated?

(1). If the product standard only specifies that it is direct, it must be executed according to the standard;

. Sample requirements are not specified in the product standard and both vertical and horizontal measurements are taken

Try to check every color as much as possible, noting the ones that can’t be checked horizontally.

Q2. How fast is the woven laundry wash color when specified in the standard for knitted products evaluated only in the vertical direction?

Woven fabrics are evaluated in type and weave directions.

Q3. GB / T 14576–1993 In “Fabric Color Fast Test, Lightness and Sweat Composite Color Speed”, how should the rating be determined when the sample is unevenly dispersed after testing?

According to the most severe color classification.

Q4. SN / T 0309–1994 Ultraviolet Fluorescence Testing Method for “Imported and Exported Fabric Fluorescence” has a strong fluorescence (non-removable impurity) somewhat similar to that of fabrics. Can this situation be defined? Does it contain fluorescent material?

It is defined as containing fluorescent material.

Q5. For multi-component fiber fabrics, choose textile fabrics. Can the same group of fibers belong to the same group? For example, fabric fiber content: 45% cotton, 25% polyester, 15% wool, 15% rabbit hair. Wool and rabbit hair can be classified as wool and should cotton and wool be used for single fiber coats?

When selecting lining fabrics, the fibers of the same group can be classified into one category, and the lining fabric can be selected according to the corresponding standards.

Hemp: Rami, flax, jute, kenaf, etc. Viscose, Model, Liocel, Kupra etc .; Wool: wool, rabbit hair, mohair, etc .; Silk: Mulberry Silk, Tusa Silk stay.

Q6. Since the test temperature for washing clothes is chosen according to the composition, can the surface and line be tested only according to the fabric composition when testing the garment?

According to standard requirements, the washable temperature of fabrics and linings is selected according to their components.

Q7. Color striped fabrics, printed fabrics and yarn dyed fabrics change color after rapid testing (water resistance, sweat resistance, soap resistance) after testing. How to grade and judge?

When preparing samples, apply as much dark color as possible on the dark and light parts. For multi-colored fabrics, wide and narrow striped fabrics, multi-composite samples can be cut and graded according to the most intense color.

Q8. GB 12982–2004 How can the end of the exposure be determined if the “national flag” cannot supply the consumer with radiant energy?

Refer to GB / T 7.2.3–3 at 8427 (Method 1998) for “Fabric Color Speed ​​Testing Color Artificial Light Speed: Xenon-Arc.”

Q9. GB / T 6.2.3–8427 1998 No Section “Testing Fabric Color Faster Artificial Light Faster: Xenon-Arc” Standard. GB 12982–2004 Does the light food test method comply with 7.2.3?

Lightness testing of GB 12982–2004 shall be carried out in accordance with GB / T 7.2.3–8427 1998.

Q 10. During rapid color testing of wool fabrics, there are spots and stains. How to rate it?

According to the deepest spots.

Q 11. During the color acceleration test for perspiration and water fastness, water stain marks appear on the samples after the test and the water stain marks disappear by hand rubbing. How to rate?

Grade it after removing the watermark.

Q 12. How to choose a line for color fast testing of silk and acetate fiber blended fabrics?

Individual fiber coats are used in accordance with the following standards: GB / T 7568.8–2014 “Fabric Color Fabric Testing Standard Part 8: Diositic Fibers” and GB / T 7568.6–2002 “Fabric Color Fast Test Wire Standard Sticker Lining Fabric Specification.

8. Reasons for poor color The fastness of silk fabrics and their care

The main component of silk fabrics is natural protein fibers. This feature makes it more breathable and soft than other fabrics. But because of this feature, mulberry silk fabrics have an unbearable shortcoming. That is, there is no high level of color fastness.

Proteins do not work well at high temperatures, so high temperature processing is not acceptable for mulberry silk. In the dyeing process, high-temperature dyeing and high-temperature fixing cannot be performed. This is a major reason why its color fastness does not increase.

Furthermore, acid dyes are commonly used for dyeing because proteins are easily damaged in an alkaline environment. Fabrics dyed with acid dyes are brighter and fuller, but the colors are not as fast.

A large portion of silk fabric dyes are bound to fade. These include light shades of light yellow, silver-gray, pink, light green, light blue, etc. Silk dresses in these colors are not resistant to sunlight. Many bright colors are easy to erase among the medium colored silk fabrics like gold, orange, light green, bright blue, bright pink, ground red and the like. The worst colors are gray and some darker shades of grass, various grays, browns, yellows, and the like. Most dark silk dresses are easy to erase, especially red, purple, bright blue, educated green, and so on. They are almost bound to disappear.

Detergent Selection: Chemical detergents are generally not suitable for silk fabrics. If it contains underwear or dirty stains, it is recommended to use a neutral bath lotion for washing.

Water temperature control: High water temperature is the second largest source of silk fabric. When washing, do not use hot water soak, be sure to use cold water at room temperature, and avoid soaking for long periods of time. Otherwise, it turns silky yellow. If you use hot water and soak for a long time, it will stain the whole pot of water!

Scratching method: Silk fabrics are different from pure cotton and chemical fiber fabrics. Silk fabrics cannot be machine washed. When washing at home, you should use hand washing and do not rub too hard. It is advisable to use “wash” or “wash”. Wherever you can, use a soft towel soaked in detergent to wipe gently.

Final drying: Silk has poor light resistance and prolonged absorption of ultraviolet light can cause yellowing and eningue. Therefore, when drying, you should avoid direct sunlight and keep the back side of clothes in a cool place. When they are 80 to 90% dry, remove them and iron them with a medium-sized iron to keep them shiny and durable. Also, avoid spraying water when ironing, be sure not to iron the front to prevent water stains.

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