認識色牢度 | What is Color Fastness?

色牢度 （Color fastness）又稱染色牢度、染色堅牢度。是指紡織品的顏色對在加工和使用過程中各種作用的抵抗力。根據試樣的變色和未染色貼襯織物的沾色來評定牢度等級。紡織品色牢度測試是紡織品內在質量測試中一項常規檢測項目。

紡織品在其使用過程中會受到光照、洗滌、熨燙、汗漬、摩擦和化學藥劑等各種外界的作用，有些印染紡織品還經過特殊的整理加工，如樹脂整理、阻燃整理、砂洗、磨毛等，這就要求印染紡織品的色澤相對保持一定牢度。

色牢度好與差，直接涉及人體的健康安全，色牢度差的產品在穿著過程中，碰到雨水、汗水就會造成面料上的顏料脫落褪色，則其中染料的分子和重金屬離子等都有可能通過皮膚被人體吸收而危害人體皮膚的健康，另一方面還會影響穿在身上的其它服裝被沾色，或者與其他衣物洗滌時染臟其他衣物。

(相關閱讀: 衣物髒汙清洗技巧 | How to deal with Clothing Stains?)

染色牢度

所謂染色牢度（簡稱色牢度），是指染色織物在使用或加工過程中，經受外部因素（擠壓、摩擦、水洗、雨淋、曝晒、光照、海水浸漬、唾液浸漬、水漬、汗漬等等）作用下的退色程度，是織物的一項重要指標。因織物在加工和使用過程中所受的條件差別很大，要求各不相同，故現行的試驗方法大部分都是按作用的環境及條件進行模擬試驗或綜合試驗，所以染色牢度的試驗方法內容相當廣泛。

但縱觀國際標準組織（ISO）、美國染色家和化學家協會（AATCC）、日本（JIS）、英國（BS）等諸多標準，最常用的還是耐洗、耐光、耐摩擦及耐汗漬、耐熨燙、耐氣候等項。而在實際工作中，主要是根據產品的最終用途及產品標準來確定檢測項目，如毛紡織產品標準中規定必須檢測耐日晒色牢度，針織內衣當然要測耐汗漬牢度，而戶外用紡織品（如遮陽傘、燈箱布、蓬蓋材料）則當然要檢測其耐氣候色牢度。

染色牢度的概念

染色牢度是對染色、印花織物的品質要求。因為染過色的織物在穿著和保管中會因光、汗、摩擦、洗滌、熨燙等原因發生裉色或變色現象，從而影響織物或服裝的外觀美感。染色狀態變異的性質或程度可用染色牢度來表示。織物的染色牢度與纖維種類、紗線結構、織物組織、印染方法、染料種類及外界作用力大小有關。

可分為日曬牢度、水洗或皂洗牢度、摩擦牢度、汗漬牢度、熨燙牢度和昇華牢度等。

1． 日曬牢度

日曬牢度是指有顏色的織物受日光作用變色的程度。其測試方法既可採用日光照曬也可採用日光機照曬，將照曬後的試樣褪色程度與標準色樣進行對比，分為8級，8級最好，1級最差。日曬牢度差的織物切忌陽光下長時間曝曬，宜於放在通風處陰乾。

2． 洗滌牢度

水洗或皂洗牢度是指染色織物經過洗滌液洗滌後色澤變化的程度。通常採用灰色分級樣卡作為評定標準，即依靠原樣和試樣褪色後的色差來進行評判。洗滌牢度分為5個等級，5級最好，1級最差。洗滌牢度差的織物宜乾洗，如若進行濕洗，則需加倍注意洗滌條件，如洗滌溫度不能過高、時間不能過長等。

3． 摩擦牢度

摩擦牢度是指染色織物經過摩擦後的掉色程度，可分為幹態摩擦和濕態摩擦。摩擦牢度以白布沾色程度作為評價原則，共分5級（1~5），數值越大，表示摩擦牢度越好。摩擦牢度差的織物使用壽命受到限制。

4． 汗漬牢度

汗漬牢度是指染色織物沾浸汗液後的掉色程度。汗漬牢度由於人工配製的汗液成份不盡相同，因而一般除單獨測定外，還與其他色牢度結合起來考核。汗漬牢度分為1~5級，數值越大越好。

5． 熨燙牢度

熨燙牢度是指染色織物在熨燙時出現的變色或褪色程度。這種變色、褪色程度是以熨斗同時對其他織物的沾色來評定的。熨燙牢度分為1~5級，5級最好，1級最差。測試不同織物的熨燙牢度時，應選擇好試驗用熨斗溫度。

6． 昇華牢度

昇華牢度是指染色織物在存放中發生的昇華現象的程度。昇華牢度用灰色分級樣卡評定織物經幹熱壓燙處理後的變色、褪色和白布沾色程度，共分5級，1級最差，5級最好。
正常織物的染色牢度，一般要求達到3級以上才能符合穿著需要。

日晒牢度測試儀

洗滌牢度測試儀

摩擦牢度測試儀

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Colour fastness is a term used in the dyeing of textile materials, meaning resistance of the material's colour to fading or running. The term is usually used in the context of clothes. The first known use of the word colorfast was in 1916. In general, clothing should be tested for colourfastness before using bleach or other cleaning products.

Color Fastness:

Color fastness is one of the important factors in case of buyers demand. The outstandingly important property of a dyed material is the fastness of the shade of color. Color fastness refers to the resistance of color to fade or bleed of a dyed or printed textile materials to various types of influences e.g. water, light, rubbing, washing, perspiration etc. to which they are normally exposed in textile manufacturing and in daily use. We have written a lot of articles on color fastness.

General Principle:

A specimen of the textile to be tested, with the adjacent fabric attached is subjected to washing under specifiend conditions. Te extent of any change in color and that of the staining of the adjacent fabric are assessed and the rating is expressed in fastness numbers.

There are two types of adjacent fabrics; (1) single fibre fabric and multiple fibre fabric. In the case of multifiber fabric only one specimen is required and in the of single fiber fabric two adjacent faabric are required.

Standards of Color Fastness: 

1. AATCC (American Association of Textile Chemists and Colorists) technical manual:
Describes 66 numbers of different color fastness tests.

2. SDC (Society of Dyers and Colorists):
In 1927, SDC (Europe) made fastness test committee.

3. ISO(International Organization for Standardization):
In 1947, ISO made color sub committee. ISO also grades the fastness:
For light fastness: 1~8
For other fastness: 1~5

Factors Affecting the Color Fastness Properties: 

1. The chemical nature of the fiber. For example, cellulosic fibers dyed with reactive or vat dyes will show good fastness properties. Protein fibers dyed with acid mordant and reactive dyes will achieve good fastness properties and so on. That is to say compatibility of dye with the fiber is very important.
2. The molecular structure (e.g.) of a dye molecule: If the dye molecule is larger in size, it will be tightly entrapped inside the inter-polymer chain space of a fiber. Thus the fastness will be better.
3. The manner in which the dye is bonded to the fiber or the physical form present.
4. The amount of dye present in the fiber i.e. depth of shade. A deep shade will be less fast than a pale or light shade.
5. The presence of other chemicals in the material.
6. The actual conditions prevailing during exposure.

If the color removes itself from the garment onto the cloth, you should not use the cleaning product on the clothing. Important color fastness tests are given below:

1. Color Fastness to Washing
2. Color Fastness to light
3. Color Fastness to perspiration
4. Color Fastness to Water
5. Color Fastness to Rubbing
6. Color Fastness to Crocking

Color Fastness to Washing

In the test, change in color of the textile and also staining of color on the adjacent fabric are assessed. A 10 x 4 cm swatch of the coloured fabric is taken and is sandwitched between two adjacent fabric and stitched, The sample and the adjacent fabric are washed together. FIve different types of washing are specified as different washing mthods.

Fastness to Wash
Sr.No	Method	Washing severity	Soap+Soda in grams/liter	Time in minutes	Temperature	Steel balls
1	IS:687:79	Very mild like hand wash	5	30	40+/- 2	Nil
2	IS:3361:79	5 times severe than method 1	5	45	50+/- 2	Nil
3	IS:764:79	Mild washing	5 + 2	30	60+/-2	Nil
4	IS:765:79	Severe washing	5 + 2	30	95+/-2	10
5	IS:3417:79	Severe washing	5 + 2	4 hrs	95+/-2	10

The solution for washing should be prepared to the required temperature of washing. The liquor material ratio is 50:1 . After soaping treatment, remove the speciment, rinse twice in cold water and then in running cold water under a tap. Squeeze it and air dry at a temperture not exceeding 60°C. The change in color and staining is evaluated with the help of grey scales.

Color Fastness to light

The purpose of Color fastness to light test is to determine how much the color will fade when exposed to a known light source. It is an off line quality assurance system. Generally man wears the fabric and goes outside of the home for doing their job. In day; sun light fall on the fabric surface. So it needs to know how much protection ability have a fabric to sun light. It is determined by an experiment called color fastness to light. To measure the color fastness a blue scale is used. After completing the test, sample is compared with the blue scale.

Principle of Color Fastness to Light: 

This test measures the resistance to fading of dyed textile when exposed to day light. The test sample is exposed to light for a certain time which is about 24 hours to 72 hours or by customer/buyer demand and compare the change with original unexposed sample the changes are assessed by Blue Scales.

Light Fastness Grades:

Grade	Degree of Fading	Light Fastness Type
8	No fading	Outstanding
7	Very slight fading	Excellent
6	Slight fading	Very good
5	Moderate fading	Good
4	Appreciable fading	Moderate
3	Significant fading	Fair
2	Extensive fading	Poor
1	Very extensive fading	Very poor

Color Fastness to Perspiration:

The garments a\which come into contact with the body where perspiration is heavy may suffer serious local discoloration. This test is intended to determine the resistance of color of dyed textile to the action of acidic and alkaline perspiration. Before knowing about the Color Fastness to perspiration you must have to know about Color Fastness to Wash and Color Fastness to Rubbing.

Color Fastness to Water

Color fastness to water is designed to measure the resistance to water of dyed, printed, or otherwise colored textile yarns and fabrics.The test method by which this test is carried out is AATCC 107-1991 or ISO 105 E01. This method is to assess the degree of cross staining which may occur when garments are left in contact when damp. The test measures the resistance to water of any colored textiles.

Color Fastness to Rubbing

This test is designed to determine the degree of color which may be transferred from the surface of a colored fabric to a specify test cloth for rubbing (which could be dry and Wet).

There are two test methods for rubbing fastness.

1.ISO-105-X12
2.AATCC-08

In ISO-105-X12 the wet pickup of the rubbing cloth is 100% .While in AATCC-08 the wet Pickup of the rubbing cloth is 65%.We check rubbing by Dry and Wet methods. In wet rubbing we wet the rubbing cloth according to test method and give rating by comparing the Staining with the gray scale.

Similarly for dry rubbing we check the rubbing with dry rubbing cloth and compare the staining With gray scale for ratings.Color Fastness to rubbing is a main test which is always required for every colored fabric either it is Printed or dyed.

If the color fastness to rubbing is good then its other properties like Washing fastness and durability etc improves automatically because the rubbing is a method to check the fixation of the color on the fabric. So if the fixation is good its washing properties will be good.

Rubbing Fastness depends on: 

Nature of the Color
Depth of the Shade
Construction of the FabricNature of the color Each color either it is pigment ,Reactive ,Disperse or direct has its own fastness properties to rubbing. There are some colors like black, Red ,Burgundy ,Navy blue which have poor Color fastness properties because of their chemical structure.

Like Black color is a carbon base color and the particle size of carbon is large than the other colors that's why its rubbing properties are poor. Similarly red and blue are in the same case. So to improve the color fastness we add more binder to improve the fastness properties of these colors. It doesn't mean that we can not achieve the best results with these colors. The required results can achieve but production cost will be increase. On the other hand the construction of the fabric also effects the fastness properties.

If the rubbing fastness on 100.80/40.40 is 3 on the gray scale it will be 2-3 on 52.52/22.22 with the same printing parameters. So always keep in mind these effects during finalize the required parameters with your customer.

Color Fastness for Crocking

Crocking is simply the transfer of color from a fabric onto another white test fabric. The more color is transferred, the more the fabric "crocks". Crocking determines the amount of color transferred from the surface of colored textile material to other surfaces by rubbing.

編排整理 Edited by: ACOTEX Fabric Talks 布料知識庫