colour fastness

COLOUR FASTNESS

1.1. COLOUR FASTNESS

It is a fundamental requirement that the colored textiles should withstand the conditions

encountered during processing following coloration and during their subsequent useful life.

Consideration of the subject of color fastness here is deliberately directed to an examination of the

factors which determine the behavior of textile materials, when subjected to the conditions encountered

during processing and use, and the principles upon which color-fastness testing must, in consequence, be

used

When a colored textile is subjected to particular conditions, e.g. light, washing, milling, and

bleaching, one or more of several things may happen. As far as the color of the material itself is

concerned there may be an alteration in depth, or in hue, or in brightness. In certain cases there may be

alteration in all three. Thus a red material may become paler, yellower and duller. Further, under certain

conditions, e.g. during washing, adjacent white material may become colored and colored material may

acquire new color due to the transfer of dye from the original dyed material. This is generally described

as 'staining’ or 'marking-off ’.

The ‘color fastness’ of a textile is therefore defined as its resistance to these changes when

subjected to a particular set of conditions. It follows that color fastness must be specified in terms of

these changes and expressed in terms of magnitude.1

1.2. HISTORICAL DEVELOPMENT

Systematic color-fastness testing began with the efforts of individuals within particular firms.

Thus when in 1902 James (later sir James) Morton discovered how fugitive were the dyeing of many of

the synthetic dyes, he set out to produce a range of tapestries and furnishing fabrics which would stand

with repeated washing and prolonged exposure to light.

The first serious attempt to establish standard methods of color-fastness testing was made by

the German Society of Chemist, who in 1911, set up a Fastness Committee. The Society of dyers and

Colorists, who in 1927, set up a fastness committee, which presented its first report in 1934, under took

the pioneer work. In 1947 the International Organization for Standardization (ISO) was set up.

1.3. FACTORS AFFECTING CHANGE IN COLOUR AND STAINING

1

When a coloured material is subjected to particular conditions e.g. light, washing, milling and

bleaching, the Colour may change in depth, hue or brightness. In some cases there may be alteration in

all three. Thus a blue dyed fabric may become paler, yellower and duller. The resistance of a coloured

material to any such change in colour is termed as its colourfastness. Also, during wet treatments such as

washing and dry-cleaning, adjacent undyed material may take up colour due to transfer of dye from the

original dyed material. This is known as staining. The substrate to which dye has been applied also

affects the fastness properties. It is thus essential that while reporting colorfastness grades, the substrate,

as well as the change in hue, value and chroma must be specified.2

The color changes which occur when dyed or printed textiles are subjected to a particular agency

during processing are due to one, or both, of the following main causes. The first is breakdown of the

colorant itself inside the fiber whereby it is converted in to colorless or differently colored compounds

--- a very complex matter indeed. The second is detachment of the colorant, as such, from the fiber.

Staining of surrounding areas in the same material occurs if the detached colorant is substantive towards

either the original substrate or any other fibrous material with which it comes in contact during exposure

to the agency. Staining is particularly likely to occur during exposure to conditions similar to those

encountered when the material was being dyed or printed, i.e. during contact with water, wash-liquor

etc. The possible effect on color fastness of a change in the color of the fibrous substrate itself is a result

of exposure to the particular conditions must not be overlooked.

1. The chemical structure of the colorant: -

The resistance of a dye or pigment to chemical or photochemical attack is directly related to its

chemical structure. Thus the relatively high fastness to light of dyeing of anthraquinone acid dyes on

wool and the poor light fastness of triarylmethane acid dyes on the substrate are directly attributable to

the stability of the one and the instability of the other to photochemical attack. Similarly, the good

fastness to oxidizing/ bleaching agents of anthraquinonoid vat dyes on cellulosic fibre is related to the

high stability of such compounds to oxidation.

Where two or more dyes are present in the fibre, one may catalyze the breakdown of another. A

well known example of this, but certainly not the only one, is the ‘catalytic fading’ of dyeing of mixtures

of vat dyes on exposure to light, particularly greens produced using mixtures containing certain yellow

dyes. The progressive yellowing which occurs on exposure to light arises from acceleration in the rate of

breakdown of the blue component due to the presence of the ‘active’ yellow dye. Incidentally, when

such active dyes are present alone or in presence of dyes, which are not so affected, photochemical

attack on the fibrous substrate, it self may be promoted with consequent serious tendering of the fibre

and the weakening of the material.

2

The resistance of a dye or pigment to chemical or photochemical attack is an inherent property of

the dye chromophore but the auxochromes may also substantially alter the fastness either way. Thus the

good lightfastness of anthraquinone base natural dyes on wool and silk and the very poor fastness of

curcumin and annatto dye on the same substrate are directly attributable to the stability of the one and

the instability of the other chromophore to photochemical attack. The light fastness of hydroxyl

anthraquinones and concluded that the fastness decreases as the number of hydroxyl groups increases.

The decrease of light fastness depending on position of substituent. In anthraquinone nucleus, –SH, -

NH, -NHR or aquinoline nucleus decreases the light fatness, while –NO2 has a favorable effect.2

When two or more natural dyes are present on the fibre, there might be a complete change in

tone of colour with time because of dissimilarities in the fading behaviour. This effect is readily

observed in old tapestries. In these historic textiles, green colours produced by over dyeing indigo with a

natural yellow dye, inevitably to a bluer hue of the higher light fastness of the indigo (blue) component.3

2. The state of the colorant in the fibre: -

The state of the colorant in the fibre is obviously important. The superiority of the reactive dyes

over the direct dyes in respect of fastness to wet treatments on cellulosic fibres is the direct result of the

covalent attachment of the reactive dye to the fibre compared with the attachment of the direct dye

through reversible forces, such as hydrogen bonds and other secondary attractive forces. In a dyeing or

print of a reactive dye the colorant molecule and the fibre molecule become one-entity. In the case of

dyeing of direct dyes on cellulosic fibres reversal of the dyeing process is fairly easily initiated since dye

absorption and retention is due to weak forces of attraction which are easily over come.

The very high fastness to wet treatments of dyeing and prints of, e.g., vat dyes, azoic

combinations, and the small collection of dyes classified as Ingrain dyes in the Color Index, is due

primarily to the fact that the dye inside the fibre is in the form of relatively large particles of insoluble

colorant which, resistant to removal during wet treatments e.g. washing. At the same time the presence

of the colorant in the fibre in this form also results in an improvement in its stability to chemical attack

owing, presumably, to the in accessibility of the bulk of it to the attacking chemical. The overall high

fastness of the anthraquinonoid vat dyes on cellulosic materials, which has led to their setting the

standard of performance, is the net results of their high chemical stability and their presence in the fibre

as particles which are insoluble in water and in aqueous solutions of the majority of chemicals used in

textile processing, with the notable exception of alkaline solution of reducing agents.

3. The amount of colorant present on the fibre

3

The colour fastness of a deep dyeing or print of a particular dye often differs markedly from that

of a pale dyeing or print of the same dye on the same material. Where the principal effect of exposure to

the particular conditions is to produce a change in the colour of the material, e.g. as is the case with

exposure to light, it is generally found that the deeper the dyeing or print (i.e. the greater the amount of

dye present on the fibre) the higher is its fastness in respect of change in colour on exposure. In certain

cases the fastness to light of a deep dyeing may be two or more points higher (on the 1-8 scale) than that

of a pale dyeing of the same dye. This is explained in part by the fact that the deeper the dyeing the

greater the amount of dye, which must be destroyed before a visible change in the colour of the material,

becomes apparent. In certain cases the situation is complicated by the fact that the colorant is present in

the fibre in the form of large particles of pigment. In this case even a pale dyeing or print contains a

relatively large amount of colorant in a state in which it is least susceptible to photochemical attack and

thus the effect of depth of colour on light fastness is much less pronounced, or even absent. The high

fastness to light of pale dyeing and prints of pigments resin-bonded to the fibre is a very good example

of this. In the case of conditions such as washing, water, dry heat (disperse dyes) etc., the fastness of a

dyeing or print in respect of staining of adjacent materials decreases as the depth of dyeing increases.

This is easily understood, since the greater the amount of dye present the more likely is it that during

exposure sufficient to cause staining will be detached from the material.

The light fastness of a dyed fibre usually increases with increasing dye concentration. If a dyed

sample is exposed to light, the number of molecules, which will be modified during a specified period,

will be the same; irrespective of the percentage of dye on the fabric.4 Net fading is therefore greater in

pale shades. In certain cases, however, improvement in fastness of deeper shades could be caused by

aggregation of dye molecules within the fibre.5 It is because of this reason that it has become customary

to state the fastness of a dye on a given fabric in three strengths of shade (e.g. 0.25, 1 and 2.5%).

4. The fibre: -

The Colourfastness of coloured textiles is related to the chemical structure and physical

characteristics of the fibre itself. The wet fastnesses of disperse dyes on polyester fibre is much higher

than on secondary cellulose acetate materials. This is because polyester fibres are much more compact in

structure and, consequently, diffusion of dyes within them proceeds much more slowly under given

conditions. The fastness of a coloured textile to light is influenced by effective humidity during

exposure.

Effective humidity is defined as the combination of air and surface-temperature in the relative

humidity governing the moisture content of the surface of fibre. The ability of a fibre to absorb the water

from the atmosphere, i.e. its moisture regain characteristics, is thus obviously important in this

4

connection. Finally, the physical dimensions of the fibres or filaments may be determining factor. The

higher fastness to light of certain direct dyes on high filament denier viscous staple fibre for carpets is

attributed to the lower surface area: volume ratio compared with that of the low filament denier yarns

used for other textile purposes.

5. Foreign substances: -

Substances other than the colorant may be present in the fibre. These include moisture,

delustrants, e.g. titanium dioxide, residual dyeing assistants, examples carriers used when dyeing

polyester fibre, after treating agents, finishing agents, e.g. synthetic resins deposited in the fibre to

confer crease-shedding properties, and agents deliberately applied to improve colour fastness to a

particular agency. Titanium dioxide can catalyze photochemical attack and thus the light fastness of a

dye on titanium dioxide delustured fibres may be lower than on the bright material. It has been known

that the presence of no more than traces of certain carrier, e.g. o-phenyl phenol, in dyed and printed

polyester materials can reduce light fastness by as much as two points on the 1-8 scale. The reduction in

light fastness of many dyes on cellulosic fibres that can result from resin finishing must be taken into

account when selecting dyes for use in these circumstances. Cationic compounds applied to dyeing of

direct dyes on cellulosic fibres to improve fastness to wet treatments can also exert adverse influence on

light fastness. Fluorescent brighteners can affect the color fastness of textiles in two ways. Firstly,

because of the relatively low stability to light of fluorescent brighteners on some substrates, materials

treated with them may yellow on exposure. Secondly, absorption of these brighteners by coloured

materials during washing can bring about a considerable change in appearance when the materials are

subsequently viewed under illuminants containing a significant amount of ultraviolet radiation. Pale

yellows, creams and fawns are particularly affected.

Antioxidants such as gallic acid, cathechol, and tannins exhibit limited protective action on some

dyes. After treatment of dyes with tannic acid and treatment of cotton with myrobolans before and after

dyeing improves the fastness properties of most natural dyes. On the other hand, presence of substances

such as TRO, starch and gums etc. might accelerate the fading process.2

6. Temperature and humidity: -

Under normal conditions of exposure to light, both temperature and humidity affect the rate of

fading of dyed textile materials.6 The role of relative humidity and temperature of fading of museum

textiles dyed with natural dyes have been investigated. It was found that a drop in relative humidity from

65 to 45% had very little effect but a further decrease to 25% relative humidity caused a significant

reduction in fading. For fugitive dyes, a rise in temperature from 25 to 35˚C resulted in an increase in

fading rate by a factor of 1.5.5

7. Atmospheric contaminants: -

Atmospheric contaminants, such as SO2 and oxides of nitrogen and ozone are known to react

with dyes even in absence of light. It has shown that fading of some, but not all natural dyes is reduced

in an inert gas atmosphere such as nitrogen or argon, but there is also evidence to show that madder and

alkanet dyes in watercolors fade more in an inert atmosphere. Several researchers have reported that an

NO2 gas is one of the prominent causes of dye fading.7 Sulphur dioxide and ozone are also responsible

for colour changes.

8. Effect of mordant: -

Most natural dyes are mordant dyes. The fastness of a mordant dye depends on the mordant and

mordanting method, because different metal dye complexes are formed, which may differ in their

stability to light and also because the metal may have a positive or negative catalytic photochemical

degradation of the dye. A recent study on 18 yellow natural dyes concluded that the mordant was more

important than the dye itself in determining the light fastness of coloured textile. Studies have also been

conducted employing natural mordant such as tannins, paddy clay, bentonite and lanthanite to improve

fastness of dyeing to light and washing.2

9. Nature of incident light: -

Not all absorbed wavelength in the visible and ultraviolet are equally effective in initiating a

fading process. It has shown that fugitive dyes are faded mainly by UV radiation.8 Use of a UV filter has

been shown to afford some protection to natural dyes. Cotton dyed with brazilwood on alum mordant

had its colour preserved fairly well when UV filters were employed. Dyes, which fade only in UV light,

are those that absorb strongly in the region 200-320 nm, while dyes, which are fast to both types of light,

are transparent throughout the UV region.

The ultraviolet content is particularly important because U.V. radiation is high-energy radiation

and hence highly destructive. Infrared radiation is important because it is absorbed by textile fibres with

consequent rise in the temperature of the material and reduction in its moisture content, which affect

fading.

2. BASIC PRINCIPLES

In order to determine the fastness of a coloured textile to a particular agency, e.g. light, washing,

it is necessary to submit a sample of it to conditions which represent that agency, and to estimate the

6

magnitude of any consequent change in the color of the sample under test, and, where relevant, the

extent to which adjacent undyed materials, exposed with the sample, become coloured (stained).

The validity of any particular fastness test and hence the value of the results depends upon a

number of conditions being satisfied.

(1) Generally the test must simulate as closely as possible the conditions encountered when the

material is exposed to the particular agency during processing and use. The establishment of

such conditions can, in many cases, be a very difficult matter, as is revealed by published

accounts of the development of certain test methods, e.g. fastness to perspiration. In these

instance very considerable investigations was necessary in order to produce ‘artificial’

perspiration the behavior of which resembled that of the natural product.

(2) The test must be readily reproducible.

(3) The method of assessing change in color of the sample and staining of adjacent white materials

must be as objective as possible; otherwise the results value will be only to the person carrying

out the test and of only limited and temporary value even to him.

(4) When the purpose of the test is to determine the fastness characteristics of a particular dye on a

given substrate the results obtained must be related to the depth of dyeing or print.

(5) The time required to carry out the test and to asses the result must be as short as possible,

consistent with reproducibility and accuracy, since further progress in the manufacturer and

marketing of the textile often has to await the results of the test.2

3. TYPES OF COLOUR FASTNESS 9,10,11

The colour fastness test methods is divided into groups according to property

GROUP A – GENERAL PRINCIPLES

ISO 105-A01: 1994 – General principles of testing

ISO 105-A02: 1993 – Grey Scale for assessing change in colour.

ISO 105-A03: 1993 – Grey Scale for assessing staining.

ISO 105-A04: 1989 – Methods for the instrumental assessment of the degree of

staining of the fabrics.12

ISO 105-A05: 1996 – Instrumental assessment of change in colour for determination of

Grey Scale rating.13

ISO 105-A06: 1995 – Instrumental determination of 1/1 standard depth of colour.

7

ISO 105-A08: 2001 – Vocabulary used in colour measurement

GROUP B – COLOUR FASTNESS TO LIGHT AND WEATHERING

ISO 105-B01: 1994 – Colour fastness to light (day light).

ISO 105-B02: 1994 – Colour fastness to artificial light (Xenon arc fading lamp).

ISO 105-B03: 1994 – Colour fastness to weathering (outdoor exposure).

ISO 105-B04: 1994 – Colour fastness to artificial weathering (Xenon arc fading lamp

test).

ISO 105-B05: 1993 – Detection and assessment of photochromism

ISO 105-B06: 1998 – Artificial light at high temperatures (Xenon arc fading lamp test).

ISO 105-B08: 1995 – Quality control of blue wool reference

materials 1 to 7.

GROUP C – COLOUR FASTNESS TO WASHING AND LAUNDERING14

ISO 105-C01: 1989 – Colour fastness to washing (test 1)





ISO 105-C06: 1994 – Colour fastness to domestic and commercial laundering.

ISO 105-C07: 1999 – Colour fastness to wet scrubbing of pigment printed textiles.

ISO 105-C08: 2001 – Colour to domestic and commercial laundering using a non

phosphate reference detergent incorporating a low temperature

bleach activator.15,16

ISO 105-C09: 2001 – oxidative bleach response using a non-phosphate reference

detergent incorporating a low temperature bleach activator.17,18

ISO 105-C12: 2004 – Colour fastness to industrial laundering

GROUP D –COLOUR FASTNESS TO DRY CLEANING

ISO 105-D01: 1993 – Colour fastness to dry cleaning.

ISO 105-D02: 2001 – Colour fastness to rubbing (organic solvent)

8

GROUP E – COLOUR FASTNESS TO AQUEOUS AGENCIES

ISO 105-E01: 1994 – Colour fastness to water.

ISO 105-E02: 1994 – Colour fastness to seawater.

ISO 105-E03: 1994 – Colour fastness to chlorinated water.

ISO 105-E04: 1994 – Colour fastness to perspiration.

ISO 105-E05: 1989 – Colour fastness to spotting (acid).

ISO 105-E06: 1989 – Colour fastness to spotting (alkali).

ISO 105-E07: 1989 – Colour fastness to spotting (water).

ISO 105-E08: 1994 – Colour fastness to hot water.

ISO 105-E09: 1989 – Colour fastness to potting.

ISO 105-E10: 1994 – Colour fastness to decatizing.

ISO 105-E11: 1994 – Colour fastness to steaming.

ISO 105-E12: 1989 – Colour fastness to milling (alkaline).

ISO 105-E13: 1994 – Colour fastness to acid felting (severe).

ISO 105-E14: 1994 – Colour fastness to acid felting (mild).

GROUP F – STANDARD ADJACENT FABRIC

There are ten parts in this group, each of which specifies different adjacent fabrics used in the other

groups of the standard. F01 to F08 are ‘specifications for standard adjacent fabric’; F01 – wool, F02 –

cotton & viscose, F03 – polyamide, F04 – polyester, F05 – acrylic, F06 – silk, F07 – secondary acetate

and F08 – triacetate. F09 – standard rubbing cloth and F10 – adjacent fabric (multifibre).

GROUP G – COLOUR FASTNESS TO ATMOSPHERIC CONTAMINANT

ISO 105-G01: 1993 – Colour fastness to nitrogen oxides.

ISO 105-G02: 1993 – Colour fastness to burnt-gas fumes.

ISO 105-G03: 1993 – Colour fastness to ozone in the atmosphere.

ISO 105-G04: 1989 – Colour fastness to oxides of nitrogen in the atmosphere at high

humidities.

GROUP H – COLOUR FASTNESS OF TEXTILE FLOOR COVERING

GROUP J – MEASUREMENT OF COLOUR AND COLOUR DIFFRENCES

9

ISO 105-J01: 1997 – Measurement of colour and colour difference.

ISO 105-J02: 1997 – Instrumental assessment of whiteness.

ISO 105-J03: 1995 – Calculation of colour differences.

GROUP N – COLOUR FASTNESS TO BLEACHING AGENCIES

ISO 105-N01: 1993 – Colour fastness to bleaching (Hypochlorite).

ISO 105-N02: 1993 – Colour fastness to bleaching (Peroxide).

ISO 105-N03: 1993 – Colour fastness to bleaching (Sodium chlorite; mild).

ISO 105-N04: 1993 – Colour fastness to bleaching (Sodium chlorite; severe).

ISO 105-N05: 1993 – Colour fastness to stoving.

GROUP P – COLOUR FASTNESS TO HEAT TREATMENT

ISO 105-P01: 1993 – Colour fastness to dry heat (excluding pressing)

ISO 105-P02: 2002 – Colour fastness to pleating (steam pleating).

GROUP S – COLOUR FASTNESS TO VULCANIZING

ISO 105-S01: 1993 – Colour fastness to vulcanization (hot air).

ISO 105-S02: 1993 – Colour fastness to vulcanization (sulfur monochloride)

ISO 105-S03: 1993 – Colour fastness to vulcanization (open steam)

GROUP X – COLOUR FASTNESS TO MISCELLANEOUS AGENCIES

ISO 105-X01: 1993 – Colour fastness to carbonizing (AlCl3).

ISO 105-X02: 1993 – Colour fastness to carbonizing (H2SO4).

ISO 105-X04: 1994 – Colour fastness to mercerization.

ISO 105-X05: 1994 – Colour fastness to organic solvents.

ISO 105-X06: 1994 – Colour fastness to soda boiling.

ISO 105-X07: 1994 – Colour fastness to cross dyeing (wool).

ISO 105-X08: 1994 – Colour fastness to degumming.

ISO 105-X09: 1993 – Colour fastness to formaldehyde.

ISO 105-X10: 1993 – Assessment of migration of textile colours into polyvinyl

chloride coating.

ISO 105-X11: 1994 – Colour fastness to hot pressing.

ISO 105-X12: 2001 – Colour fastness to rubbing.

10

ISO 105-X13: 1994 – Colour fastness of wool dyes to processes using chemical means

for creasing, pleating and setting .

ISO 105-X14: 1994 – Colour fastness to acid chlorination of wool (sodium

dichloroisocyanurate).

ISO 105-X16: 2001 – Colour fastness to rubbing (small areas).

GROUP Z – COLORANT CHARACTERISTICS

ISO 105-Z01: 1993 – Colour fastness to metals in the dye bath (chromium salts).

ISO 105-Z02: 1993 – Colour fastness to metals in the dye bath (iron and copper).

ISO 105-Z03: 1996 – Intercompatibility of basic dyes for acrylic.

ISO 105-Z04: 1995 – Dispersibility of disperse dye.

ISO 105-Z05: 1996 –Determination of dusting behavior of dyes.

ISO 105-Z06: 1998 –Evaluation of dye and pigment migration.

ISO 105-Z07: 1995 –Determination of application solubility and solution stability of

water soluble dyes.

ISO 105-Z08: 1995 –Determination of the electrolyte stability of reactive dyes.

ISO 105-Z09: 1995 –Determination of cold water solubility of water-soluble dyes.

ISO 105-Z10: 1997 –Determination of relative colour strength in solution.

ISO 105-Z11: 1998 –Evaluation of speckiness of disperse colorant

4. TEST PROCEDURES

Normally determination of Colourfastness is based on subjecting a test sample to specified

conditions for a specified time and assessing the magnitude of the changes thereby produced using the

Grey Scales as the absolute standard of reference.

4.1. General Test Procedures: -

(1) Specimen of the coloured textile, with undyed materials attached if staining is also to be

determined, is subjected to the particular agency using the specified procedure.

(2) The extent and nature of any change in the Colour of the textile and the extent of staining of the

adjacent undyed materials are assessed and recorded.

4.2. Specification of colourfastness: -

11

Colourfastness is specified on the basis of a numerical, supplemented as necessary by verbal

description of Colour changes, which have occurred.

The scales are:

(a) A 1-8 (L1-L9-US practice) scale for specifying light fastness.

(b) A 1-5 scale for specifying fastness to all other agencies. Where verbal description is also

considered desirable, the terms used are:

Redder, bluer, greener, yellower.

Weaker, stronger.

Duller, brighter.

4.3. Assessment of change in Colour: -

This includes alteration in depth, hue, or brightness, or any combination of these. Regardless of

the character of the change, the assessment is based on the magnitude of the visual contrast between the

original material and the sample.

This could be determined quantitatively by instrumental measurement of the reflectance

characteristics of the sample. Such a procedure would require expansive apparatus, would be time

consuming and the data obtained would be unnecessarily complicated to handle.

On the other hand if the color contrast is assessed by visual examination without reference to any

standard contrasts, the result will be imprecise and very liable to subjective human error. The current

mandatory method for assessment of color contrast in fastness testing is visual examination of the

original and tested materials alongside a series of quantitatively specified contrast as reference

standards. The series of standard contrast is known as the Grey Scale for Assessing Change in Colour,

and consists of five pairs of the pieces of grey card numbered 1-5. The contrast between pair no.5 is zero

that between pair no. 1 is 13.6 CIE Lab units. The series of contrast forms a geometrical progression.

The original and tested samples are placed side-by-side and viewed under a suitable illuminant. Each of

the pairs of grey is placed along side in turn and the number of the pair showing a contrast nearest to that

shown by the samples is noted. The fastness rating of the sample under test is the number of the grey

scale contrast, which is closest to the contrast between the original, and the treated specimen. If that

contrast lies between two contrasts on the scale an intermediate rating, e.g. 3-4 is given.

When the color change includes a change in hue and/or in brightness and it is desired to record

the character of the change, adding the appropriate qualitative description using the following

terminology does this.

12

(1) Redder(R) Yellower(Y) Bluer(B) Greener(G)

Weaker (W) Stronger(Str)

Duller(D) Brighter(Br)

Figure

The use of the scale and the significance of the ratings obtained are summarized and illustrated

by the following examples.

(2)

RATING MEANING

3 Contrast-Grade 3 of the Grey Scale

Only loss in depth of colour has occurred.

3 redder Contrast-Grade 3 of the Grey Scale

No significant loss in depth has occurred, but colour hasbecome redder, i.e. there has been a change in hue

3 Weaker, yellower Contrast-Grade 3 of the Grey Scale

Both loss in depth and a change in hue have occurred

3 Weaker, bluer, duller Contrast-Grade 3 of the Grey Scale

A loss in depth, change in hue, and change in brightness has occurred.

4.4. Assessment of staining: -

This also is determined visually. The contrast between the face of the undyed cloth in contact

with the test sample during the test and a sample of the original undyed material is assessed using the

Grey Scale for Assessing Staining (BS 1006: A03: 1978). This scale consists of nine pairs of pieces of

card, numbered 5, 5-4, 4, ………1-2, 1, where 5 is a pair of whites and the others consists of a white and

a grey, giving a series of contrasts increasing in geometric progression, no.1 showing the highest

contrast, 36.2 CIELAB units of color difference.

The degree of staining of the undyed materials subjected to the test as part of the composite test

specimen is determined using the grey scale for assessing staining in the same manner as the grey scale

for assessing change in colour as follows: 1 (maximum contrast = lowest fastness) to 5(minimum

contrast = maximum fastness), intermediate ratings (1-2, 2-3, etc.) being recorded.

13

The great importance of the Grey Scale lies in the fact that they provide a direct, objective basis

for color-fastness assessment which has been found to be sufficiently precise, and accurate and reliable

in use, to be accepted internationally.

The only exception to the use of the Grey Scale as the ultimate reference point in fastness

assessment is in the determination of color fastness to light. In this case fastness assessment is based on

comparison of the exposed specimens with a series of eight standard, dyed wool cloths, which have been

exposed together with and under the same conditions as the material under test. The Grey Scale for

assessing change in Colour is, however, used to specify the extent to which the exposed samples are

required to fade before exposure is terminated.2

Table (1) Relation between CIELAB colour differences for fading and staining and the Grey Scale

fastness grade

CIELAB Colour differencefor fading

Colour fastness grade

CIELAB Colour difference for staining

<0.40 5 <1.100.40 – 1.25 4-5 1.10 – 3.251.25 – (1.7) – 2.10 4 3.25 – (4.3) – 5.15 2.10 – 2.95 3-4 5.15 – 7.252.95 – (3.4) – 4.10 3 7.25 – (8.5) – 10.254.10 – 5.80 2-3 10.25 – 14.455.80 – (6.8) – 8.20 2 14.45 – (16.9) – 20.458.20 – 11.60 1-2 20.45 – 29.05> 11.60 1 >29.05

Table (2) Description of the normal fastness grades

Fastness Grade Shade change oftested sample

Fastness Staining of adjacentwhite sample

Grade 5 No change Excellent No stainingGrade 4 Slight loss in depth Good Very slight stainingGrade 3 Appreciable loss Fair Moderate stainingGrade 2 Significant loss Poor Significant stainingGrade 1 Great loss in depth very poor deep staining

Table (3) Description of the light fastness grades

Fastness Grade Degree of Fading Light FastnessGrade 8 None OutstandingGrade 7 Very, very slight ExcellentGrade 6 Slight Very goodGrade 5 Moderate GoodGrade 4 Appreciable ModerateGrade 3 Significant FairGrade 2 Extensive PoorGrade 1 Very extensive very poor

14

COLOUR-FASTNESS TESTS

Colour can also play a part in colourfastness. When considering colour, blues and reds are

affected by wider bands of light (UV and infra red). These colours tend to fade quicker than central

spectral colours such as green, yellow or orange. While this isn't a fail-safe rule, the fibre and dyes used

in the fabric composition is still the most important part.19

The principles and practice of Colourfastness testing are illustrated by the following examples.

Fastness to washing and to light is very important to the producers and consumers of all kinds of

coloured textiles. Since fastness to burnt gas fumes (nitrogen oxides) is relevant, particularly to dyed

secondary acetate and triacetate, and fastness to various heat treatments is important in relation to dyed

and printed materials made from cellulose acetates and synthetic-polymer fibres.

When a coloured material is subjected to particular conditions e.g. light, washing, milling and

bleaching, the Colour may change in depth, hue or brightness. In some cases there may be alteration in

all three. Thus a blue dyed fabric may become paler, yellower and duller. The resistance of a coloured

material to any such change in colour is termed as its colourfastness. Also, during wet treatments such as

washing and dry-cleaning, adjacent undyed material may take up colour due to transfer of dye from the

original dyed material. This is known as staining. The substrate to which dye has been applied also

affects the fastness properties. It is thus essential that while reporting colourfastness grades, the

substrate, as well as the change in hue, value and chroma must be specified.2

The fastness requirements, however, are largely determined by the end-use of dyed fabrics, e.g.

perspiration fastness is not required in case of upholstery materials.

Some examples of special parameters for different end uses of fabrics4:

15

Item Special requirement

Garment for Australia Improved light fastness, UV protection

Swimwear / Beachwear Chlorinated water / Seawater Fastness, colour

fastness to light.

Towel and Napkins Absorbency

Surgical Gowns / Apparel Anti bacteria properties, colour fastness to

autoclaving, absorbency

Woolen Merchandise Moth proofing

Fire fighter apparel Fire proofing

Defense textiles (tents / canvas etc.) Protective textiles

Parachute cloth Air permeability

Soil resistant products Soil releasing fluorocarbon treatment

Oil industry applications Oil repellant finishes

Household curtains and drapability Tensile strength, colourfastness to light,

Anti flammability

Bathmats / table mats Colourfastness: migration into PVC

Upholstery Abrasion resistance

Industrial uniforms Strength, oil / soil repellency, flammability

Sportswear Abrasion resistant, seam strength and

colourfastness to perspiration

Baby wear / children wear Colourfastness to saliva

Nightwear Flammability

Rainwear Water repellency, breathability

Garment for artic condition Ability to withstand extreme cold: flexing /

strength at low temperature

Following are the test methods for evaluation of the fastness characteristics of the dyed goods:

Colour Fastness to Light

What is lightfastness?

Lightfastness is the degree to which a dye resists fading due to light exposure. Different dyes

have different degrees of resistance to fading by light. All dyes have some susceptibility to light damage,

16

simply because their strong colors are indications that they absorb the wavelengths that they don't reflect

back. Light is energy, and the energy that is absorbed by pigmented compounds may serve to degrade

them or nearby molecules.

Fastness to light is one of the most important properties in order to fulfill its utilization purpose

over a period of time. Fastness to natural daylight is the only light-fastness characteristic of colored

textile materials, which required to be known. Artificial light, as normally employed for domestic and

industrial illumination, does not cause serious fading. It can be used as an alternative to daylight for

obtaining useful information on the possible behaviour of the coloured textile on exposure to daylight

provided precautions are taken to ensure that the specified condition of exposure are complied with.20

The appropriateness of a particular lightfastness standard can be judged on the basis of three

criteria: uniformity, linearity of fading with respect to time, and sensitivity.21

Why does ultraviolet light cause color to fade?

Because of photodegradation.

It is all about the chemical makeup of an object. The technical term for color fading is

photodegradation. There are light absorbing color bodies called chromophores that are present in dyes.

The color(s) we see are based upon these chemical bonds and the amount of light that is absorbed in a

particular wavelength.

Ultraviolet rays can break down the chemical bonds and thus fade the color(s) in an object - it is

a bleaching effect. Some objects may be more prone to fading, such as dyed textiles and watercolors.

Other objects may reflect the light more, which makes them less prone to fade.22

There is a growing demand for sun protective textiles, as unfiltered ultraviolet (UV) rays mixed

with the sunlight that hit human skin cause skin tumors and ageing. UV radiation is comprised of UVA

rays of wavelength 320-400 nm, UVB rays of 280-320 nm, and UVC rays of 100-280 nm. The term sun 17

protection factor (SPF) is used for sunscreens, and ultraviolet protection factor (UPF) for textiles, to

differentiate clothing and other textiles from sunscreens. Using a spectro radiometer or

spectrophotometer, UPF is determined using the VITRO method, in which subjects are irradiated with

monochromatic light. The sun protection properties of a fabric are determined by the extent to which a

fabric transmits, reflects, or absorbs UV radiations. A fabric, which has the capacity to absorb or reflect

maximum incident light and allows little time to transmit, is more beneficial to the skin.21

Mechanism of fading

The absorption of one quantum of light of 4000ºA (the blue end of the visible spectrum)

represents an increase in the energy of dye molecule of about 71 kcal; and when this is compared with

bond energies (C-C 58.6; C-N 48.6; C-O 70.0; C=C 100; C=O 142-152; N=N 80 kcal per mole), it is

clear that light energy (particularly the energy of ultraviolet radiation) is adequate for the rupture of

bonds in organic molecules, assuming that all the absorbed light energy is available for this process. It is

thus remarkable that despite this, so many dyes exhibit such good stability to light. By the absorption of

light, a molecule rises from its ground state of lowest energy to an excited state of higher energy in

which one of the electrons is at a higher level. The life of an excited molecule is exceeding by small,

about 10-7 to 10-8 sec, for a permitted transition. The activated molecule expends the energy of excitation

in one of the several ways. It may emit radiation in the form of fluorescence or phosphorescence; or lose

its energy as heat by collision with other molecules; or dissociate to take part in chemical reaction. Even

with simple organic molecules, photochemical reactions of varied character are encountered and the

fading of dyes might involve three photochemical reactions oxidation, reduction and decomposition or

photolysis. Photosensitization may also occur. Fading of dyes by the action of light and air is usually an

oxidative process.

Lighter shades usually will fade more quickly than darker shades because they contain less dye.

Most dyes are composed of two or more color components. If one color is affected more than the other,

the fading may appear as a color change rather than a lightening of the color. For example, many

greenish hues are made from yellow and blue dyes. If the yellow dye is affected and the blue is not, the

green textile may seem to be turning blue. These green colors now appear very blue because the yellow

dye has faded.23 It is realized that dyes may be extremely complex, may contain impurities or exist in

various states of aggregation, or contain certain substituents that are photoactive in their own right.18

No direct relation between fluorescence and fading of dyes has been established, but they are

related phenomenon. Many dyes that have poor fastness to light are fluorescent in solution or on the

fibre. Fluorescent dyes are usually more photosensitive and fade more rapidly because the active life

period of their molecule is longer and the chances of collision with oxygen of the air, therefore greater.24

18

All kinds of textile fibers (native and man-made) are liable to a destructive influence of the

sunlight. Degradation reactions by light mostly occur when air oxygen and environment influence is

present and therefore all range of oxygen products arise together. UV-radiation the most harmful part of

the sunlight and also damp influences are affecting on the textile fibers. Photo degradation happens even

in vacuum or in inert atmosphere. The photo degradation is also caused by artificial sources of UV-light

the speed of photo degradation depends on the specific surface [m2/g].25

What exactly causes fading?

The sun's energy or more importantly the portion called ultraviolet radiation. Surprisingly,

ultraviolet radiation only makes up for only 2% of the sun's energy, but accounts for an estimated 60%

of the fading damage.

The quality of dyes used on fabric plays a huge part in Colour fastness. Problems often occur in

textile usage when a consumer decides to use a fabric, which had not been produced to meet certain end

uses.

Polyester and acrylic fibres are the most sunlight resistant fibres in common use. They outlast all

other commonly used textile fibres when exposed to the weather. Thus their use for curtaining is ideal.

Should the Colour fade, this is attributable to the dyestuff.19

There are three basic ways that fading occurs with dyes and lakes: -

1. Breaking of a double bond and rearrangement of the molecules shape. Double bonds can receive

enough energy to not only jump to a higher orbital, but they can break and leave the molecule, leaving a

single bond or leaving the molecule without the electrons to jump to higher orbital. A change in bonds

changes the shape of the molecule.

2. The bonds can receive enough energy to break altogether, breaking the molecule into two or more

pieces. The breaking apart of the molecule into different, smaller molecules will cause a color change,

hence the fading.

3. A small amount of the dyes that are water-soluble lose their grip on the fabric in the washing process.

These molecules are torn off of the fabric and are then rinsed away. This is a slow fading process, but

steady.26

Four general classes of color change27

1. Fading due to the destruction of the chromophore in the principal dye of the pigment.

2. Color shifts which the observer sees as a change of hue more than fading (although fading

occurs). 19

3. Metameric fading, which goes undetected under some light sources.

4. Metameric color shifts which can be caused by the oxidation of a component in the tube color.

Factors Affecting fastness to light

Lightfastness of dyed textiles is related to the chemical structure and physical characteristics of

the fibre itself. The colourfastness properties of several natural anthraquinonoid dyes on cotton and silk

have been investigated .It was found that the extent of colour fading on cellulosic fibres was directly

related to the oxidation index of each dye whereas the different systems are operated for protein fibres. 30

The fading on cellulose is an oxidative process, whereas on protein fibres, it is reductive in nature. In

another study, indigo dyeing was found to be much more light resistant on wool than on cotton while the

reverse was true of madder. The moisture regains characteristics of a fibre and its area: volume ratio is

also important determining factors.

In consequence, determination of light fastness is based on the fading behavior of standard dyed

materials exposed alongside the samples under test and under the same conditions. The ISO Standards

are eight blue dyeing on wool cloth, each produced with a different dye and forming a series ranging

from No. 1 (very low light fastness) to No. 8 (very high light fastness). The dyes used in the current ISO

blue wool scale fall into two categories; those used for light fastness standards 1 to 6 are all acid dyes,

whereas for light fastness standards 7 and 8, solubilised vat dyes are used.17

In a dyed material the physical state of the absorbed dye, i.e. the size and location of its

associated particles, as well as the structure, chemical nature, temperature and moisture of the substrate

itself, all influence the light fastness of the dyes and lead to complex kinetic effects.31

Key factors influencing photostability18

The key factors influencing the photostability of textile dyes are:

The wavelength distribution of incident radiation.

The degree of dye aggregation

The presence of moisture

20

The presence of metal ions, either inextricably bound in dyes or bound in impurities.

The chemical and physical structure of the textile substrate.

The particular dye structure.

● Colour fastness to light: daylight BS 1006

SECTION: A01, A02, B05

Scope:

This method is intended for determining the resistance of the colour of textiles of all kinds and in

all forms, and of leather, to the action of daylight.

If there is a possibility o a sample being photochromic, the test of photochromism shall be applied

additionally.

Principle:

A specimen of textile or leather is exposed to daylight under prescribed conditions, including

protection from rain, along with eight dyed wool standards. The fastness is assessed by comparing the

change in colour of the specimen with that of the standards.

1. Fabric size: 1 x 6 cm

2. Fastness rating: 1 to 8

Blue wool cloth ranging from 1 to 8

i. C.I. Acid Blue 104

ii. C.I. Acid Blue 109

iii. C.I. Acid Blue 83

iv. C.I. Acid Blue 121

v. C.I. Acid Blue 47

vi. C.I. Acid Blue 23

vii. C.I. Solubilised Vat Blue 5

viii. C.I. Solubilised Vat Blue 8

Pattern dyed with 3 dyes should be deceived after dyeing. The patterns of light fastness from 1-8 may be

obtained from ISI.

The BS 1006:1978 test of day light exposure specifies that sample should be tested together with

standard dyed wool patterns of light fastness. 1-8 respectively cover with opaque sheet of card board or

aluminum leaving the other half exposed.

21

When daylight is used fading is slow and quicker answer is often necessary under commercial

purpose. Hence, xenon arc lamp is used. The SED of this lamp bears a close resemblance to a natural

light.

Test reports:

Report the numerical rating for light fastness. It is represented by the figure alone (in

the case of using the standards denominated 1-8).

If this rating is equal to or higher than 4 and the preliminary assessment is equal to or lower than 3,

report the later figure in brackets. If the specimen is photochromic, the light fastness shall be followed

by bracketed P along with the grey scale rating20.

● Light fastness: daylight ISO 105/B01

Brief description:

Expose the test sample and light fastness scales 1-8 until a contrast on the test sample corresponding to

stage 4 and then to stage 3 on the “Grey scale Change of shade” becomes visible but no longer than

when the blue standard 7 shows a contrast corresponding to stage 4.The lightness rating corresponds to

the number of the blue standard on the blue standard on the light fastness scale which shows a similar

contrast to the test sample.

Software used for the measurement of light fastness:

Megasol light and weather-fastness apparatus to set test conditions fully automatically and to

continuously log all test parameters via a touch sensitive interactive control panel and its own design

software.

At first sight, light fastness testing seem to be a very straightforward process. Simply expose

samples of the material in question to an artificial light source, and note the elapsed time by which the

sample has faded to match a reference standard.

The Megasol light fastness/weathering test system recently introduced by Heals automatically

sets and controls the chamber conditions for up to 50 different standards including various international

standards

One of the computer control displays is a ‘test’ menu. This shows a plan view of the test chamber, with

the current status of all relevant components. The ‘Sample’ menu display shows the current exposure

duration for the A and B sides of each of 10 sample holders, highlighting the samples with longest

22

exposure time. Megasol’s computer control also provides comprehensive information on the life and the

expiry dates for the burner and each operational filter, automatically logging all changes, events and

service history in a series of screen displays within the ‘Service’ menu. When a burner or filter require

replacement, an appropriate from is displayed prior to starting a test21.

COLOUR FASTNESS TO WASHING

Fastness to washing was one of the three fastness properties investigated by the first fastness

committee set up by the SDC in 1927. Fastness to washing is one of the properties of a dyeing of

importance to the consumer.

Wash fastness properties of dyes: -

A dye must be able to withstand treatments in manufacturing processes and normal usage when

present in fibre. Thus, it should be fast to wet treatments such as washing, shampooing and

manufacturing process such as milling. Wet fastness of dyes is influenced by the rate of diffusion of

dyes and the state of dye inside the fibre.

The rate is a function of the geometry of the dye molecule i.e. it depends on the size of the molecule and

its molecular weight. Affinity of dye for fibre also tends to reduce the rate of transport of dye into or out

of the fibre. The dye-fibre attractive forces tend to cause the dye molecules to remain attached to fibre

molecules rather than to diffuse along the force of the fibre.

During the limited period of a normal washing treatment, equilibrium between the dye inside and

outside the fibre may not be reached. Thus the amount of dye removed in the case would depend largely

on its rate of desorption, so the wash fastness is expected to increase directly with the molecular weight

or volume of the dye.

State of dye inside the fibre: -

State of dye inside the fibre is very important. Direct natural dyes such as turmeric, annatto and

carthomone (from safflower) have poor wash fastness as the dye is attached to the fibre through

reversible forces such as hydrogen bonds and other weak forces of attraction, which are easily

overcome. The very high fastness to wet treatments exhibited by e.g. Indigo is due mainly to the fact

that the dye inside the fibre is in the form of relatively large particles of insoluble colorant which,

because of size and insolubility in water, are very resistant to removal during wet treatments. Similarly,

the superior wet fastness of metal complex dyes is due to the ability of dye molecules to aggregate into

large particles in fibre and not because of the adhesion forces of attraction between wool and metal ions.

23

Most washing test is carried out at relatively law temperatures for short times and the dye-fibre

system does not come to equilibrium. Desorption of the dye from the fibre is therefore influenced

mainly by kinetic factors.

There is a variety of testing procedure. To some extent, these have arisen because:

(1) Washing conditions vary from one country to another;

(2) The method depends upon the use of the material being washed;

(3) To evaluate repeated washing, accelerated test methods are used.

The situation becomes even more complicated when one considers that the degree of fading of a

dyeing on washing depends upon the following factors, all of which must be standardized:

(1) The temperature. This may range from 20˚C to as high as 95˚C;

(2) The type and amount of detergent that is added to the washing bath. This may or may not

include alkalis, phosphates, silicates, optical brightener, chlorine or peroxide bleach. In many

testing procedures, a standard detergent formulation is required;

(3) The extent of mechanical action. This can be varied by changing the agitation speed in a washing

machine or by adding steel ball bearing to the revolving test bath;

(4) The washing liquor to goods ratio and the hardness of the washing water;

(5) The rinsing, drying or pressing methods use to restore the sample after the test.

Most testing standards include several tests of increasing severity. These tests have successively

higher washing temperatures, increasing wash times, possibly decreasing liquor ratios and the more

severe tests may have higher levels of mechanical agitation as well as small amounts of chlorine bleach

in the wash.

A standard size sample of the fabric to be tested is visually stitched between two samples of white

fabric, one of the same and the other of a different type of fibre. To assess staining, it is now common

practice for one of the white fabrics is assessed with the appropriate Grey Scales or by colorimetric

measurements. The condition for ISO test for colour fastness to domestic washing and commercial

laundering are give in table 5. These tests are carried out using a wash wheel with a 5-gm/liter standard

soap solution at a liquor ratio of 50:1.

Table 4. Conditions of the ISO washing fastness tests

Test Temperature(˚C)

Time(Min.)

Steel balls

Chemicals

ISO 1 40 30 Soap24

0ISO 2 50 45 0 SoapISO 3 60 30 0 Soap + Soda ashISO 4 95 30 10 Soap + Soda ashISO 5 95 240 10 Soap + Soda ash

● Colour fastness to washing and laundering BS 1006

SECTION: A01, A02, A03

Colour fastness to washing: Test

Scope:

This is test number 1 of a five washing tests that have been established to investigate

the fastness to washing of coloured and which between them, cover the range of washing producers

from mild to severe.

NOTE: this method is designed to determine the effect of washing only on the colour fastness of

the textile. It is not intended to reflect the result of the comprehensive laundering procedure.

Principle:

A specimen of a textile in contact with specified adjacent fabrics is mechanically

agitated under specified conditions of time and temperature in a soap solution, rinsed and dried. The

change in colour of the specimen, and the staining of the adjacent fabrics, are assessed with the gray

scales.

Two adjacent fabrics, each measuring 10 x 4 cm, one piece made of the same kind of fibre as that of the

textile to be tested, or that pre-dominating in the case of blends, the second piece made of the fibre

indicated as follows or, in the case of blends, of the kind of fibre second in order of pre dominants, or as

otherwise specified.

If the first adjacent fabric is Second piece to be

Cotton Wool

Wool Cotton

Silk Cotton

Linen Cotton

Viscose Wool

Acetate Viscose

Polyamide Wool or viscose

Polyester Wool or cotton

25

Acrylic Wool or cotton

Table 1

Test specimen:

Fabric: 10 x 4 cm

Yarn: knit it in to fabric and then use as above

Loose fibre: comb and compress and make a sheet of 10 x 4 cm

Procedure:

Place the composite specimen in the container and add the necessary amount of soap solution,

previously heated to 40±20C, so as to give a liquor ratio of 50:1, test it at this condition for 30 minute.

Remove the composite specimen, rinse it twice in cold distilled water and then in cold running tap-water

for 10 minute and squeeze it. Dry it by hanging it in air at a temperature not exceeding 600C. Assess the

change in colour of the specimen and the staining of the adjacent fabrics with the grey scales.

The other tests major differ in temperature and time part.

Test 2: Treat the specimen at 50±20C, for 45minute

Test 3: Treat the specimen at 60±20C, for 30 minute

Test 4: Treat the specimen at 95±20C, for 30 minute (in the container add stainless steel balls)

Test 5: Treat the specimen at 95±20C, for 4 hour (in the container add stainless steel balls)

Test report:

Report the numerical ratings for the change in colour of the test specimen and for the staining of each

kind of adjacent fabric used.

● Colour fastness to washing AATCC method 61

Brief description:

Place test sample with adjacent fabric in a steel beaker (1250 ml volume) and treat with detergent

solution for minimum 45 minute under the conditions in table in the Launder-O-meter.

Table:

Test method

conditions

1A 2A 3A 4A 5A

Test samples 10 x 5 cm 15 x 5 cm 15 x 5 cm 15 x 5 cm 15 x 5 cm26

(adj. Fabric) (6 x 5 cm) (6 x 5 cm) (6 x 5 cm) (6 x 5 cm) (6 x 5 cm)

Temperature 400C 490C 710C 710C 490C

Detergent solution

WOB

5 g/l 2 g/l 2 g/l 2 g/l 2 g/l

Liquor 200 ml 150 ml 50 ml 50 ml 150 ml

Beaker volume 550 ml 1250 ml 1250 ml 1250 ml 1250 ml

Available chlorine - - - 150 mg/l 270 mg/l

Steel balls 10 50 100 100 50

COLOUR FASTNESS TO RUBBING (organic solvents)


all forms, except loose fibre, to the combined action of rubbing and of organic solvents used in spot-

cleaning, i.e. localized ‘spotting’ carried out by hand.

A specimen of the textile is rubbed with rubbing cotton cloth impregnated with solvent. The

change in colour of the specimen and the staining of the rubbing cotton cloth are assessed with the grey

scales.

● Colour fastness to rubbing BS 1006

SECTION: A01, A03

Scope:

This method is intended for determining the resistance of the colour of textiles of all

kinds, including textile floor coverings and other pile fabrics, to rubbing off and staining other materials.

The method is applicable to a laid textile floor covering or to a detached sample or yarns. Two tests are

made, one with a dry rubbing cloth and one with a wet rubbing cloth.

Principle:

Specimens of the textile are rubbed with a dry rubbing cloth and with wet rubbing

cloth. Two alternative sizes of rubbing fingure are specified, one for pile fabric and one for other

textiles. The staining of the rubbing cloth is assessed with the grey scale.

Test specimen:

Fabric: 5 cm x 14 cm


Loose fibre: comb and compress and make a sheet of 5 cm x 14 cm

Procedure:

27

Fasten each test specimen by means of clamps to the base board of the testing device so that the long

direction of the specimen follows the track of the device.

Dry rubbing: with the dry rubbing cloth flat in place over the end of finger of the testing device

rub it to and fro in a straight line along a track 10 cm long on the dry specimen, 10 times to and fro in 10

second, with a downward force on the finger of either 22 N or 9 N

Wet rubbing: repeat the test described with a fresh dry specimen and with a rubbing cloth that has been

wetted with water, by placing it on the grating and dropping evenly onto its own mass of water, or use

any method to ensure a take-up of about 100%. After rubbing, dry the cloth at room temperature.

Assess the staining of the rubbing cotton cloths with the grey scale.

Test report:

Report the numerical rating for dry staining and for wet staining for each direction of

manufacture.

COLOUR FASTNESS TO PERSPIRATION


all forms to the action of human perspiration.

Specimens of the textile in contact with specified adjacent fabrics are treated in two different

solutions containing histidine, drained, and placed between two plates under a specific pressure in a

testing device. The specimens and the adjacent fabrics are dried separately. The change in colour of each

specimen and the staining of the adjacent fabrics are assessed with the grey scale.

● Colour fastness to perspiration BS 1006


Scope:


kinds and in all forms to the action of human perspiration.

Principle:

A specimen of textile in contact with specified adjacent fabrics are treated in two

different solutions containing histidine, drained, and placed between two plates under a specific pressure

in a testing device. The specimen and the adjacent fabrics are dried separately. The change in colour of

each specimen and the staining of the adjacent fabrics are assessed with the gray scales.

Two adjacent fabrics, each measuring 4 x 10 cm, one piece made of the same kind of fibre as

that of the textile to be tested, or that pre-dominating in the case of blends, the second piece made of the

28

fibre indicated as follows or, in the case of blends, of the kind of fibre second in order of pre dominants,

or as otherwise specified.


Cotton Wool

Wool Cotton

Silk Cotton

Linen Wool

Viscose Wool

Acetate Viscose

Polyamide Wool or viscose



Test specimen:

Fabric: 4 x 10 cm



Procedure:

Thoroughly wet one composite specimen in each of the standard alkaline and acid solutions

prepared as suggested at a liquor ratio of 50:1 and allows them to remain in the solution at room

temperature for 30 minute. Press and then time to time to endure good and uniform penetration of the

liquor. Pour off the solutions and wipe it also from the specimen. Then place each composite specimen

between two glass or acrylic resin plates measuring about 6 x 11.5 cm under a pressure of 12.5 kPa. Use

separate apparatus for the alkaline and aid test.

Place both sets of apparatus containing a composite specimen in the oven for 4 hour at 37±2 0C.

Then take out and dry it by hanging it in air at a temperature not exceeding 600C, with the three parts in

contact only at the remaining of stitching. Assess the change in colour of each specimen and the staining

of the adjacent fabrics with the grey scales.

Test report:

For each of the solution specified, report the numerical rating for the change in colour of the test

specimen and for the staining of each kind of the fabric used in the test.

Standards for Breathable Fabrics

29

Water vapour permeability (WVP) or water vapour transmission (WVT) is the ability of fabric to

transport water vapour and is commonly referred to as ability of a fabric to “breathe”. This fabric

property is some important to clothing comfort. The human body continuously produces insensible

perspiration (in the form of water vapour) and /or sensible perspiration (liquid sweat) to balance the

body heat generated from daily activities of varying intensities. Ultimately its purpose is to maintain a

constant body temperature.

Standard testing methods

The following outlines the standard test methods used in different countries; UK, USA, Japan, Canada,

Australia and Germany.

British standards

BS 7209, British standard specification for water vapour permeable apparel fabrics

BS 3546 coated fabrics for use in the manufacture of water penetration resistant clothing, part 4.

specification for water vapour permeable coated fabrics

BS 3424 part: 34 methods 37, testing coated fabrics, method for determination of water vapour

permeability index (WVPI).

In these three methods a test specimen is mounted on the open mouth of an upright dish/cup that

contains water. The assembled dish or cup is weighed at pre-determined intervals. The loss in water

mass is used to determine the water vapour permeability of the sample.

A reference fabric is used in these methods as a control cloth, tested simultaneously with the specimens.

A ratio is calculated between the control and test cloth in the manner of calculating the percentage

effectiveness. In this way error due to temperature fluctuation in the testing conditions can be reduced or

eliminated.

The various test methods of international standard are briefly discussed in the paper including, US,

Japanese, Canadian, Australian and German22.

● Colour fastness to hot pressing: BS 1006

SECTION: A01, A02, A03,

BS 1051

Scope:


kinds, and in all forms to ironing and to processing on hot cylinders.

Principle:

30

Dry pressing: the dry specimen is pressed with a heating device of specified temperature and pressure

for a specified time.

Damp pressing: the dry specimen is covered with a wet cotton adjacent fabric and pressed with a heating

device of specified temperature and pressure for a specified time.

Wet pressing: the upper surface of the wet specimen is covered with a wet cotton adjacent fabric and

pressed with a heating device of specified temperature and pressure for a specified time

Test specimen:




Procedure:

The following temperatures are used:

110±20C

150±20C

200±20C

When necessary, other temperatures may be used, providing they are specially noted in the test report.

Specimens of material that have been subjected to any heat or drying treatment shall be allowed to

condition in the standard atmosphere for testing textiles i.e. 65±2% relative humidity and a temperature

of 20±20C, before they are tested.

For dry pressing, place the dry specimen on top of the cotton cloth covering the wool flannel pad. Lower

the top plate of the heating device and leave the specimen for 15 second at the specified pressing

temperature.

For damp pressing, place the dry specimen on top of the cotton cloth covering the wool flannel padding.

Soak a piece of cotton adjacent fabric measuring 10 cm x 4 cm in distilled water and squeezed or extract

it to contain its own mass of water. Place the wet fabric on top of the dry specimen. Lower the top plate

of the heating device and leave the specimen for 15 second at the specified pressing temperature.

For wet pressing: Soak the specimen and a piece of cotton adjacent fabric measuring 10 cm x 4 cm in

distilled water and squeezed or extract them to contain their own mass of water. Place the wet specimen

on top of the dry cotton cloth covering the wool flannel pad and place the wet adjacent fabric on the

specimen. Lower the top plate of the heating device and leave the specimen for 15 second at the

specified pressing temperature.

31

Asses the change in colour of the specimen of colour and the staining of the cotton adjacent fabric with

the appropriate grey scale.

Test report:

Report the test procedure and the temperature of the heating device. Report the numerical rating for

change in colour immediately after testing and after conditioning for 4 hour in the standard atmosphere

for testing textiles.

COLOUR FASTNESS TO AQUEOUS AGENCIES

(A) COLOUR FASTNESS TO WATER : -

The method is intended for determining the resistance of the colour of textiles of all kinds and in

all forms to immersion in water.

A specimen of the textile in contact with specified adjacent fabrics is immersed in water, drained

and placed between two plates under a specific pressure in a testing device. The change in colour of the

specimen and the staining of the adjacent fabrics are assessed with the grey scales.

(C) COLOUR FASTNESS TO CHLORINATED WATER

(Swimming-bath water): -


all forms to the action of active chlorine in concentrations such as is used to disinfect swimming-bath

water (break point chlorination).

A specimen of the textile is treated with a very weak chlorine solution and dried. The change in

colour of the specimen is assessed with the grey scale.

● Colour fastness to aqueous agency

● Colour fastness in water: BS 1006


Scope:


kinds and in all forms to immersion in water.

Principle:

A specimen in textile in contact with specified adjacent fabrics is immersed in water,

drained and placed between two plates under a specified pressure in a testing device, the specimen and

the adjacent fabrics are dried separately. The change in colour of the specimen and the staining of the

adjacent fabrics are assessed with the gray scales. 32

Two adjacent fabrics, each measuring 10 x 4 cm, one piece made of the same kind of fibre as that of the

textile to be tested, or that pre-dominating in the case of blends, the second piece made of the fibre

indicated as follows or, in the case of blends, of the kind of fibre second in order of pre dominants, or as

otherwise specified.


Cotton Wool

Wool Cotton

Silk Cotton

Linen Wool

Viscose Wool

Acetate or triacetate Viscose

Polyamide Wool or cotton



Table 1

Test specimen:

Fabric: 10 x 4 cm



Procedure:

Thoroughly wet the composite specimen in distilled water at room temperature. Pour off the

water and place the composite specimen between two glass or acrylic resin plates, measuring about 11.5

6 cm, under pressure of 12.5 kPa.

Place the apparatus containing the composite specimen in oven for 4 hour at 37 ± 20C.

Open out the composite specimen and dry it by hanging it in air at a temperature not exceeding

600C, with the three parts in contrast at the remaining line of stitching.

Assess the change in colour of the specimen and the staining of the undyed adjacent fabric with

the grey scales.

Test report:

Report the numerical rating for change in colour and the numerical rating for staining of each kind of

adjacent fabric used.

33

● Water fastness ISO E01

Brief description:

Wet out the test sample with adjacent fabrics completely with demineralized water at room

temperature, pour off excess water, place test sample between two glass or acrylic plastic plates loaded

with a pressure of 12.5 kPa (5 kP/40 cm2) and place in a drying oven for 4 hr at 37 0C. Hang to dry in

warm air at max. 60 0C.

(B) COLOUR FASTNESS TO SEA WATER : -

The method is intended for determining the resistance of the colour of textiles of all kinds and in

all forms to immersion in water.

A specimen of the textile in contact with specified adjacent fabrics is immersed in a solution

containing sodium chloride, drained placed between two plates under a specific pressure in a testing

device. The specimen and the adjacent fabrics are dried separately. The change in colour of the

specimen and the staining of the adjacent fabrics are assessed with the grey scales.

● Colour fastness to seawater BS 1006

SECTION: A01, A02, 03 Scope:


kinds and in all forms to immersion in seawater.

Principle:

A specimen in textile in contact with specified adjacent fabrics is immersed in a

solution containing sodium chloride, drained, and placed between two plates under a specific pressure in

a testing device. The specimen and the adjacent fabrics are dried separately. The change in colour of the

specimen and the staining of the adjacent fabrics are assessed with the gray scales.

The arrangement of the two adjusting fabric is as similar to given in table 1

Test specimen:

Fabric: 10 x 4 cm



Procedure:

34

Thoroughly wet the composite specimen in the solution at room temperature. Pour off the

solution and place the composite specimen between two glass or acrylic resin plates measuring 11.5 x

6.0 cm under a pressure of 12.5 kPa. Place the apparatus in the oven for 4 hour at 37 ± 20C

Open out the composite specimen and dry it by having it in air at a temperature not exceeding

600C, with the three parts in contact only at the remaining line of stitching. Assess the change in colour

of the specimen and the staining of the adjacent fabric with the grey scales.

Test report:

Report the numerical rating for change in colour and the numerical rating for staining of each

kind of adjacent fabric used.

● Sea water fastness ISO E02

Brief description:

Wet out the test sample and adjacent fabrics completely in a 30 g/l sodium chloride solution at

room temperature, pour off excess solution, place the test sample between two glass or acrylic plastic

plates under a pressure of 12.5 kPa (5 kp/40 cm2) and place in a drying oven for 4 hr. at 37 0C. Hang to

dry in warm air at max. 60 0C.

(C) COLOUR FASTNESS TO CHLORINATED WATER

(Swimming-bath water): -


all forms to the action of active chlorine in concentrations such as is used to disinfect swimming-bath

water (break point chlorination).

A specimen of the textile is treated with a very weak chlorine solution and dried. The change in


● Colour fastness to chlorinated water (swimming bath water) BS 1006

SECTION: A01, A02

Scope:


kinds and in all forms to the action of active chlorine in concentrations such as are used to disinfect

swimming-bath water (break point chlorination).

35

Principle:

A specimen of textile is treated with a very weak chlorine solution and dried. The

change in colour of the specimen is assessed with the grey scale.

Test specimen:

Fabric: 10 x 4 cm



Procedure:

Immerse the specimen in sodium hypochlorite solution (standard prepared), liquor ratio 100:1,

ensuring that the specimen is thoroughly wetted. Close the container and allow it to stand at 20 ± 2 0C for

4 hour in subdued light.

Remove the specimen from the container, squeeze or hydro-extract it to contain its own mass of

solution, and dry it by hanging it in air at room temperature. Assess the change in colour with the grey

scale.

Test report:

Report the numerical rating for change in colour.

● Chlorinated water fastness ISO E03

Brief description:

Wet out test sample thoroughly in sodium hypochlorite solution, liquor ratio 100:1.

Alternatives

Treat with

20 mg/l available chlorine at 27 0C for 1 hr., pH 7.5



Squeeze and hang to dry at room temperature.

(5) COLOUR FASTNESS TO SPOTTING

(A) ACID SPOTTING: -


all forms to the action of dilute solutions of organic and mineral acid. Three tests differing in severity

are provided. Any or all may be used, depending upon the nature of the fiber. 36

Drops of the acid solution are placed on the specimen, the surface of which is rubbed gently

with a glass rod to ensure penetration. The changes in colour of the textile, while it is still wet and after

drying are assessed with the grey scale.

(C) WATER SPOTTING: -


all forms to spotting by water.

When the specimen is a textile a droplet of distilled water is worked in to the textile with a glass

rod, and the change in colour is assessed with the grey scale after 2 min, and after drying.

● Colour fastness to spotting: acid BS 1006

SECTION: A01, A02

Scope:

This method is intended for determining the resistance of the colour of textiles of all kinds and in all

forms to the action of dilute solutions of organic and mineral acids.

Principle:

Dorps of the acid solution are placed on the specimen, the surface of which is rubbed gently with

a glass rod to ensure penetration. The changes in color of the textile, while it is still wet an after drying,

are assessed with the grey scale.

Test specimen:




Procedure:

Spot the specimen at room temperature with the appropriate solution so that after working the

solution into temperature specimen with the glass rod a spot of diameter approximately 20 mm is

formed.

Dry the specimen by hanging it in air at room temperature. Assess the change in colour with the

grey scale.

Teat report:

Report the numerical rating for change in colour for each kind of acid used.

37

● Acid fastness ISO E05

Brief description:

Drip on to the test sample at room temperature a sufficient amount of the relevant acid solution.

b. acetic acid (300 g/l glacial acetic acid) or

c. sulphuric acid (50 g/l sulphuric acid conc.) or

d. tartaric acid (100 g/l tartaric acid crystal)

So that after working it into the test sample with a glass rod a spot of about 20 mm diameter is obtained.

Hang the test sample to dry at room temperature.

Assessment: change of shade damp (after 10 min) and dry with grey scale ‘change’ with mention of the

acid.

(B) ALKALI SPOTTING: -


all forms to the action of dilute alkaline solutions.

Drops of a solution of sodium carbonate are placed on the specimen, the surface of which is

rubbed gently with a glass rod to ensure penetration. The changes in colour of the textile are assessed

with the grey scale.

● Colour fastness to spotting: alkali BS 1006

SECTION: A01, A02

Scope:

This method is intended for determining the resistance of the colour of textiles of all kinds and in all

forms to the action of dilute alkaline solutions.

Principle:

Dorps of solution of sodium carbonate are placed on the specimen, the surface of which is

rubbed gently with a glass rod to ensure penetration. The changes in color of the textile, while it is still

wet an after drying, are assessed with the grey scale.

Test specimen:



38


Procedure:

Spot the specimen at room temperature with the appropriate solution so that after working the

solution into temperature specimen with the glass rod a spot of diameter approximately 20 mm is

formed.

Dry the specimen by hanging it in air at room temperature. Assess the change in colour with the

grey scale.

Teat report:

Report the numerical rating for change in colour.

● Alkali fastness ISO E06

Brief description:

Drip onto the test sample at room temperature a sufficient amount of sodium carbonate solution (100g/l)

so that after working it into the test sample with a glass rod a spot of about 20 mm in diameter is

obtained. Hang the test sample to dry at room temperature.

Assessment: change of shade with Grey scale “change of shade”.

(C) WATER SPOTTING: -


all forms to spotting by water.

When the specimen is a textile a droplet of distilled water is worked in to the textile with a glass

rod, and the change in colour is assessed with the grey scale after 2 min, and after drying.

(1) COLOUR FASTNESS TO DRY CLEANING


all forms to dry cleaning. This method is not suitable for the evaluation of the durability of the textile

finishes, nor is it intended for use in evaluating the resistance of colours to spot and stain removal

procedures used by the drycleaner.

In this method a specimen in contact with a cotton fabric bag, together with non-corrodible steel

discs, is agitated in tetrachloroethylene (perchloroethylene), then squeezed or centrifuged, and dried in

hot air. The change in colour of the specimen is assessed with the grey scale.

At the conclusion of the test the coloration of the solvent is assessed by comparing the filtered

solvent with unused solvent by transmitted light, by means of the grey scale for assessing staining.

● Colour fastness to dry cleaning: BS 1006

39


Scope:


kinds and in all forms, to dry cleaning.

Principle:

A specimen of the textile in contact with a cotton fabric bag, together with non-corrodible steel

discs, is agitated in tetrachloroethylene, then squeezed or centrifuged, and dried in hot air. The change in


At the conclusion of the test the colouration of the solvent is assessed by comparing the filtered

solvent with unused solvent by transmitted light by means of the grey scale for assessing staining.

Procedure:

Prepare a bag with inside dimensions of 10 cm x 10 cm using the undyed cotton twill cloth by

sewing together two squares of this cloth around three sides. Place the specimen and 12 steel discs inside

the bag. Close the bag by any convenient means. Place the bag containing the specimen and the steel

disc in the container and add 200ml of tetrachloroethylene at 30±20C. Treat the specimen for 30 minute

at30±20C in the specified equipment.

Remove the bag from the container withdraw the specimen, place it between absorbent paper or cloth

and squeeze and centrifuge to remove surplus solvent. Dry the specimen by hanging it in air at

temperature of 60±50C.

Test report:

Report the numerical rating for the change in colour of specimen and the numerical rating for

staining of solvent.

● Dry cleaning fastness ISO D01

Brief description:

Sew the test sample with 12 steel plates into a cotton bag (10 cm x 10 cm), place in a stainless steel

beaker of 550 ml volume and treat with 200 ml perchloroethylene for 30 min at 300c in the Launder-O-

meter.Then remove the test sample, squeeze or hydroextract and hang to dry in warm air at 600c.

COLOUR FASTNESS TO OZONE IN THE ATMOSPHERE

40


all forms to the action of ozone in the atmosphere both at ambient room temperatures with relative

humidity not exceeding 65% and at elevated temperatures with relative humidity above 80%.

1. A specimen of the textile and the test-control fabric are exposed simultaneously to ozone in an

atmosphere under ambient room temperatures with relative humidity not exceeding 65%, until

the test-control fabric shows a colour change corresponding to that of a standard of fading. This

exposure period continues one cycle. The cycles are repeated until the specimen shows a definite

colouir change or for a prescribed number of cycles.

2. A specimen of the textile and the test-control fabric are exposed simultaneously to ozone in an

atmosphere which is maintained at 85±5% relative humidity and a temperature of 40±5°C until

the test control fabric shows a colour change corresponding to that of a standard of fading. The

cycles are repeated until the specimen shows a definite colour change or for a prescribed number

of cycles.

3. The fading of dyes on certain fibers does not readily take place at humidity below 80%. A test at

high humidity is required to produce colour change that predicts service fading under warm,

humid conditions.

Colour fastness to ozone in the atmosphere BS 1006

SECTION: A01, A02

Scope:


kinds and in all forms to the action of ozone in the atmosphere both at ambient room temperatures with

relative humidity not exceeding 65% and at elevated temperatures with relative humidity above 80%.

Principle:

A specimen of the textile and test-control fabric are exposed simultaneously to ozone

in the atmosphere under ambient room temperatures and relative humidity not exceeding 65%, until the

test-control shows a colour change corresponding to that of a standard of fading. This exposure period

constitutes one cycle. The cycle are repeated until the specimen shows a definite colour change or for a

prescribed number of cycles.

A specimen of the textile and test-control fabric are exposed simultaneously to ozone

in the atmosphere which is maintained at 85±5% relative humidity and a temperature of 40±50C until the

test-control fabric shows a colour change corresponding to that of a standard of fading. The cycle are

repeated until the specimen shows a definite colour change or for a prescribed number of cycles.

41

The fading of dyes on certain fabric does not readily take place at humidity below

80%. A test at high humidity is required to produce colour change that predicts service fading under

warm, humid conditions.

Test specimen:

Fabric: 10 x 6 cm



Procedure:

Under relative humidity not exceeding 65 %:

Suspend the specimen and a piece of test-control fabric in the exposure chamber so as they hang

separately, at room temperature 18-280C and relative humidity 65%. Ozone should be present in

concentrations that produce one cycle of fading in 1.5 hour to 6 hour of test.

Compare the colour of the test-control fabric with that of the standard of fading periodically in daylight

ranging from average to a slightly bluish North sky light, or equivalent artificial light.

Under high relative humidity:

Here the chamber is maintained at 85±5 % relative humidity and a temperature of 40±50C. ozone should

be present in concentrations ranging from 10 to 35 parts per hundred million (by volume), which should

produce one cycle of fading in 6 hour to 24 hour of test.

● Colourfastness to ozone in the atmosphere ISO G03

Brief description:

Expose the test sample and control dyeing for the test at 18-280C and maximum 65% relative

humidity (low humidity=AATCC 109) and for the rest at 39-410C and 85-90% relative humidity (high

humidity=AATCC 129)

In a special chamber with an ozone lamp until the shade of the controlled dyeing has changed to agree

with that of the standard dyeing 109 or 129= 1 cycle (testing time generally up to maximum 4 cycles)

42

colour fastness

Documents