How Many Kinds of Color Fastness Tests and Color Fastness Testers?

 

The colorfastness property of textiles is a very important parameter from a selling point of view. Numerous factors can affect the fabric’s original shade, so quality assurance regarding colorfastness is essential.

In this article, we will discuss the most important testing methods for the colorfastness of textiles. Let’s see which parameters have the most impact on clothing color yield.

Colorfastness

“Color fastness is the property of a dye that enables it to retain its color in original depth and tone throughout the wear life of the product to which it has been applied.”

Colorfastness

The dye should not fade out whenever you buy the fabric or garment after frequent laundering or other uses. It should stick to the fabric and not bleed to other metals or fabric.

The pigment or dye should retain its original hue, especially without fading, running, or changing when wetted, washed, cleaned, or stored under normal conditions and exposed to light, heat, or other influences.

It is not the limit just for laundering. The dye should not fade even in light, heat, rubbing, and sweating exposure. That is the ultimate purpose of the color fastness test.

Colorfastness of Dyed Textiles

There are so many factors that affect colorfastness of textiles. The main four parameters are below.

Colorfastness of Dyed Textiles

Every garment is washed after use, so color fastness to washing is crucial.

All the garments we wear will be rubbed in metal parts while sitting on chairs or tables or when we are moving, so to evaluate the color’s fastness to rubbing, the fabric is rubbed with white cotton to determine the staining and fading.

In the daytime, textiles are exposed to sunlight, some other tube light, or any light source. Because of that light, there might be changes in color variations, which are measured by colorfastness to light.

Colorfastness to perspiration is because of sweat in the body or because of liquid that will generate so many resources, affecting the bleeding or shade difference in the fabric.

 

 

Color Fastness to Washing

Color Fastness to Washing

This test measures the ability of the fabric to withstand the effect of laundering. Normally, fabric washing is done in homes for 30 – 60 minutes.

During that time, we have to check how the color of the fabric, whether a shade difference will happen, or if it will bleed or something like that.

For measuring this industry, a wash color fastness tester which is called WashTrue washing fastness tester used to evaluate the colorfastness with the help of grayscale.

WashTrue Color Fastness to Washing Tester (1cylinder & 2 cylinders)

The washing of fabric results in the removal of dye. Therefore, staining can occur. See, anyway, after washing, dye will come out of the fabric. Because of this, the dye will be stuck to the other fabric.

To determine the staining, a white multi-fiber strip is attached to the specimen tested for ISO CO3 washing. That is known as washing color fastness.

The CF to washing summary is;

• The ability of the fabric to withstand the effect of laundering.
• A launder-o-meter is used to evaluate the colorfastness of washing with the help of grey scales.
• The washing of the fabric results in the removal of dye, therefore staining can occur.
• To determine the staining a white multifiber strip is attached to the specimen being tested for CF to washing.

Test Preparation

The test procedure is prescribed by AATCC. The test specimen is cut into 2 x 6 inches for a multifiber stripe.

In the multi-fiber strip, many fabrics, such as viscose wool, cotton, and nylon, will be attached to that fiber, so more than six strips will be there. The dimensions will be 2 x 6 inches.

In the WashTrue Color Fastness Tester, there is a water bath. Place the sample in a water bath, the specimen will be rotated.

                                                                                                                      Specimen Rotated in Water Bath

The water going to be heated by the heating element will raise the temperature based on the required parameters. The temperature may be raised from 40 degrees to 100 degrees centigrade.

The water bath will be rotated where the actual laundering takes place in the home, and the simulation of the laundering takes place in the home so that the color will be bleeding or stained on the adjacent fabric.

The AATCC describes the five washing tests. We can do the test method in two forms. One, we can attach the multi-fiber fabric with the fabric we will test, or we can attach the cotton fabric to the fabric we will test.

Five Washing Tests

If you attach the cotton fabric, these are the five tests prescribed by the AATCC. For the first three, we will choose wool fabric, and for the fourth and fifth, we will choose viscose fabric.

The percentage of detergent, temperature, and time of rotating that water bath have been mentioned.

Sometimes, we will add steel balls to give abrasion in the fabric so that we will give for heavy fabric. The material required ratio we must follow is 1:50, so we can choose any method based on the garment’s end use.

Evaluation of Colorfastness to Washing

The evolution of the CF to washing is the assessment of the color portion carried out by assigning ratings for the two aspects.

• Change in Colour of the test specimen
• Staining of adjacent fabric

                                                                                                                        Evaluation of Colorfastness to Washing

Two things can happen when we wash the garment. The change of shade in fabric takes place and the second thing the adjacent cloth can get staining from the garment.

The staining effect on each fiber in the cotton or multi-fiber test fabric should be rated using a grayscale. It is checked after the effect of bleeding or color migration. For the washing test, AATCC 124 standard detergent is used.

Here are the key points for the evaluation of colorfastness to washing.

• The staining effect on each cotton or multifiber test fabric fiber should be rated using the grey scale or evaluating staining.
• It is checked afterward for the effect of bleeding or color migration.
• AATCC standard detergent 124 is used.

Gray Scale

Grayscale is used to give a rating for CF. The arrangement of grayscale is from light to dark. So, nine pairs of non-glossary neutral gray color chips illustrate and perceive color differences.

The rating corresponds to the color percentage rating of 5, 4 to 5, 4, 3 to 4, 3, 2 to 3, 2, 1 to 2 and 1.

Gray Scale for Colorfastness

 

How to use a Gray Scale?

                                                                                                                           How to use a Gray Scale?

The Grayscale of CF uses a class of 5 4 3 2 1 rating system. The specimen is compared with the Grayscale after finishing the laundry-o-meter process and drying.

If it matches 5, it means it is good. If matching 1, it means it is worse.

A half rating should be given between 3 to 4, 4 to 5, and 4 to 5. Sometimes, half a rating should also be given between 3 to 4, 4 to 5, and 4 to 5. This equates the difference in lightness with the color difference.

Methodology of Testing

A control fabric is usually white or undyed and assessed for staining from contact with the test material. Suppose the color meets that, affecting the adjacent white fabric result assessed by grading against ratings 04 and 05.

Grade 5 is no change in color, or it is not stained. Grade 1 means there is a drastic difference in the color. Results are assessed by grading against standard A04/A05 grayscales. Usually, one fabric specimen is used if the material is dyed or printed uniformly throughout the fabric.

                                                                                                                                   A04/A05 grayscale

The specimen chosen should represent the entire lot, which is very important. While doing sampling, you should not cut the material at the selvages. It should be in the center of the fabric and in a random way.

The multi-color printed fabric sometimes has six to eight colors. In that case, we cannot cut the fabric in all its colors. We have to cut that particular shade, and you have to attach it to the white fabric, and have to perform the test.

                                                                                                                       Gray Scale for Multi Colour Printed Fabric

Gray Scale for Staining

Grey scale for staining is also the same method you are following, but here, we will use multi-fiber, which contains acetate, cotton, acrylic, polymer, polyester, and wool.

                                                                                                                               Gray Scale for Staining

Sometimes, when we wash, we do not wash only cotton fabric in that bunch of clothes. All types of fiber are mixed.

So, in that case, we have to assess the building for all different types of fabrics so only you get a clear picture of how the color is bleeding from the base fabric.

Various constraining pairs of strips are given as listed 5 to 1. A rating of 5 means good, and 1 means poor.  This is an example of a fabric strip. Different fabric strips like acetate, cotton, nylon, polyester, acrylic, and wool can be seen.

This fabric strip is attached to the specimen we will test, and four sides are stitched. The washing test is done in a launder-odometer, with frequent washing at a certain temperature and time. We will take out the sample, dry it, and then assess it using grayscale.

 

Color Fastness to Rubbing

The other important parameter is colorfastness to rubbing. It is also called CF to crock. This testing method ensures the quality of fabric related to color fading due to contact of clothes with metallic and wooden parts, like sitting on chairs and tables.

“The rubbing of colors is called crocking.”

                                                                                                                                         Color Fastness to Rubbing

The color is stripped from the fabric because of the rubbing action. Fabric with a large number of surface dyes, like dark-color cotton fabric, tends to have a poor color portion due to cracking.

So whenever you go for a depth shade like navy blue or black, there will be a lot of dyestuff in the fabric that obviously will come out because of rubbing.

Due to poor washing, dyes are sometimes not washed off to increase the depth of the color surface. We have to wash three or four times to remove the unfixed color.

Sometimes, people do not wash, so the color will be stripped from the fabric because of rubbing.

                                                                                                                   Poor Washing Cause More Rubbing

Various components are in the crock meter platform top, and there is a clamp below the clamp. We can fix the fabric, which we are going to test, and in the basic platform below, we can fix the white un-dyed strip of fabric, and we are going to move off.

Top arm left and right about 8 times. After that, we removed the fabric and checked with the help of a grey scale. We check the color shade difference and staining on the white fabric. So, as stated earlier, we do both things in the color fashion for washing.

Test Procedure

1. Cut two specimens on bias 8 × 8 and place the test specimen on the crock meter so it will be rubbed in the bias direction.
2. Mount a dry, white crock test cloth over the finger selection of the crock meter to be rubbed in the bias direction.
3. Lower the covered finger, causing the crock test cloth to slide over the colored specimen for 10 complete cycles.
4. Remove the specimen and white test cloth.
5. Check the color variations, shade variations, and color bleeding or staining with the help of grayscale.
6. Perform a wet crocking test using the same procedure.
7. Rate the crock test clothes using the colorfastness chart.

 

Why Color Bleeds on Rubbing?

Dye gives staining in rubbing due to the following reasons.

• Fabrics with a large number of surface dyes, like dark color and cotton fabric, tend to have poor colorfastness to crocking, pigment-dyed or printed fabrics also face the same problem.
• Sometimes, dyes are not washed off to increase the depth of color and surface, which results in crocking.

 Color Fastness to Light

It is very important to color fastness to light because the garment will be exposed to sunlight all day. This is an important factor because light will influence the color variations depending on the intensity of sunlight and the kind of season.

“The ability of the fabric to withstand the sunlight is called light fastness.

                                                                                                                                           Colorfastness to Light

There will be summer, winter, autumn, and four or five seasons. This will influence the color variation in the garment. The light intensity also affects color yield.

Sometimes, the weather will be very hot or cool, influencing the attitude and internal properties of the fabric. Sunlight influences the dye’s properties, breaking down the dye bonding and leading to garment color fading.

Factors Affecting Resistance to Sunlight

The CF to sunlight depends upon the following factors.

1. Season
2. Intensity of Light
3. Inherent properties of the fabric
4. Altitude
5. Distance from the equator

 

Testing Method

The standard method of CF to light is called the sunlight method. Sunlight method samples are placed in a glass cabinet and exported sunlight from 9 am to 3 pm.

It is a time-consuming process because the sample must be placed for a long time, and the result will be after one day.

                                                                                                                 Colorfastness to Sunlight

So, as it is a time-consuming process, nowadays people are going for weather-Ometer and fade-Ometer, the most widely used instruments.

1. Weather – O Meter
2. Fade – O Meter

Weather – OMeter & Fade – OMeter

Both instruments have different light sources, and temperature and humidity are controlled within the machine. Specimen placed around the light source remains there until the end of the test.

The evaluation is done by a change of color resulting from radiation. Weather-o-meter is a newer and more versatile machine. If desired, it enables the specimen to be sprayed with water during the test.

Weatherometer

                                                                                                                                   Weatherometer

Sometimes, in rain, sunlight and rain are both exposed to the fabric. In that case, we can use a weather-o meter to get an accurate picture of color variations in the fabric.

It can also alternate light and dark periods if continuous light exposure is not desired. The conditions are used in the weather-o meter to test the fabric for outdoor finishes, tents, and rainwear.

• It enables the specimen to be sprayed with water if needed.
• It also manipulates the light and dark period if continuous exposure is not needed.
• These make it most suitable for testing fabrics for end use like outdoor, furniture, tenting, or rainwater.

So, it is clearly stated by name, in weather-o-meter, we can expose the fabric to light in real atmospheric conditions where rainfall and weather can change. Everything can be incorporated into this test.

Instruments and Fastness

1. Both machines have a carbon-arc lamp or xenon-arc lamp as the light source.
2. The degree of fastness required depends on the end-user.
3. For example, a coat material should be more colorfast than a dress shirt.
4. Similarly, clothes are not intended to be worn outside and should also have a certain colorfastness to enable drying in sunlight.

 

Weatherometer Testing Methods

There are two types of testing methods used for weather-o meters.

1. Time method
2. Standard fading method

                                              Weather-o meter Testing Methods

Here, we will discuss the Time method. Let’s have a look at it.

Time Method

1. The specimen is exposed to light for a particular amount of time.
2. After the termination of time, the specimen is taken out and evaluated.
3. The only disadvantage is that the specimen is not exposed to the same amount of light each time the test is performed.

Test Procedure

1. Cut the specimen 2.5 × 8’’ with longer dimensions lengthwise.
2. Mount the specimen in a cardholder and remove the perforated stripes so half of the specimen area will be uncovered.
3. Insert the cardboard holder into the meal holder and place it into the machine.
4. Expose the specimen for 20 hours.
5. At the end of the desired exposure period, remove the specimen and allow it to relax in the dark at room temperature for at least 02 hours to regain moisture from the air.
6. Using the grey color scale to evaluate color change determines the colorfastness rating for the test fabric.

Disadvantage

The specimen is not exposed to the same amount of light each time the test is performed.

AATCC Test Method 16 – 2004

1. Samples of the textile material to be tested and agreed upon comparison standard(s) are exposed simultaneously to a light source under specified conditions.
2. The colorfastness to light of the specimen is evaluated by comparison of the color change of the exposed portion to the masked control portion of the test specimen or unexposed original material, using the AATCC gray scale for color change or by color instrumental color measurement.
3. Light fastness classification is accomplished by evaluation versus a simultaneously exposed series of AATCC blue wool lightfastness standards.

4)  Colorfastness to Perspiration

• Perspiration can cause a fabric to change color and result in the staining of adjacent material.
• The test is attempted to simulate the actual condition. The specimen is heated for 06 hours at 38 C
• A multifiber test fabric is placed against the specimen.
• The tests were carried out and later evaluated for bleeding or color migration.
• After the test, the specimen is evaluated using the grayscale, and the average rating is reported.

Procedure

1. Cut the specimen 2(1/4)’’ × 2(1/4)’’
2. Cut the multifiber fabric 2 × 2 inches.
3. Immerse the test sample and the specimen in the acid solution for 15 min.
4. Withdraw the fabric and remove any excess liquor.
5. Place the specimen in the perspiration tester.
6. Load the tester with 10-pound pressure.
7. Place the loaded tester in an oven and heat it to 100 F for 06 hours.
8. Remove the tester from the oven and allow the fabric to dry at room temperature.
9. Remove the specimen and test cloth and compare CF to perspirationwith the grayscale.

AATCC Method 61 – 2010

• A specimen of colored textile in contact with the other fiber materials (for color transfer)
• It is a wet-out and simulated acid perspiration solution.
• Subjected to a fixed mechanical pressure and allowed to dry slowly at a slightly elevated temperature.
• After conditioning, the specimen is evaluated for color change, and the other fiber materials are evaluated for color transfer.

 

Conclusion

Colorfastness is the property of a dye that enables it to retain its color in its original depth and tone throughout the wear life of the product to which it has been applied. Various factors influence dye properties.

The major colorfastness parameters are CF to washing, rubbing, light, and perspiration. For these parameters, the launder-o meter, crock meter, weather-o meter, and perspiration testers are used, respectively.

 

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