Study on cost effectiveness of silk dyeing with acid dyes and basic dyes

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Bangladesh University of Textiles

Project title

Study on cost effectiveness of silk dyeing with acid dyes and basic dyes

Examination 2014

Supervised by

Dr. Mohd. Forhad Hossain

Assistant Professor & Head, Department of Wet Process Engineering

Bangladesh University of Textiles

Submitted by

Student Name ID

Md. Al-Amin 2011-01-049

Shakil Mahmud 2011-01-097

Nazmun Nahar 2011-01-098

Md. Ariful Islam 2011-01-140

Md. Saifur Rahman 2011-01-157

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Acknowledgement

Project work is essential in order to make us enable to carry out potential research work in

relevant field. This will also enhance our analytical skill in finding out the root of a problem

and to solve that.

While we are of course solely responsible for the contents in our research on “Study on cost

effectiveness of silk dyeing with acid dyes and basic dyes. “In completing of our project work

at first we are grateful to almighty ALLAH and then come to the human league who contributed

a lot to make our project a solid one.

We would like to thank our project supervisor, Dr. Mohd. Forhad Hossain (Assistant Professor

& Head, Dept. of Wet Process Engineering), BUTex, for his supervision, advice and guidance

from the very early stage of this research. In spite of his busy work schedule he had helped us.

This paper would not have been possible without his vital encouragement, inspiration and

support. We are thankful for his numerous fruitful discussions and guidance with the valuable

data that we needed for carrying out our research.

We would also like to express our deep gratitude to Prof. Dr. Md. Zulhash Uddin (Dean,

Faculty of Textile Chemical Engineering), BUTex, for his patient guidance, enthusiastic

encouragement and critique of this research work and for his advice and assistance for our

progress on schedule. At all stages of the report has benefited tremendously from his support.

We appreciate his advice, comments and willingness to discuss any questions and ideas that

we have had.

We owe a particular debt of gratitude to the management of Orient Chem-Tex Ltd. for helping

us in carrying out this research work. Especially we are very thankful to Md. Mukhless ur

Rahman Khan (Director- Technical & Marketing, Orient Chem-Tex Ltd), Sazzad Wahid

(Marketing Executive), Sabitry Rani Das (Head of Laboratory) for their technical support.

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Abstract

Silk has always been the emblem of royalty due to its delicate lustrous appearance, peach like

softness and draping qualities for over thousands of years. It is a natural fibre with great

importance in the garments and clothing industry. The coloration of this valuable and high

prized fiber is also an art form. Silk dyeing is normally done either in the form of hanks or

woven pieces. Its hydrophilic characteristics and amphoteric properties enables it to be easily

dyed. There remains a numerous ranges of dyestuff to be applied on silk. Different class of

dyestuffs used for cotton or wool, can be used on silk with good result from the point of view

of dye ability with unsatisfactory level of fastness. In general, the dyestuffs are applied by

techniques similar to those of wool or cotton.

In this project, silk is dyed with acid and basic dyes after degumming it to remove sericin.

Fixation is carried out after dyeing to improve wet fastness of silk which has become an

important goal of silk dyer in order to meet customer requirements.

This project report aim to make a comparative analysis of silk dyeing with acid dye, which is

commonly applied on nylon, wool, silk and basic dye, which is more commonly used with jute,

acrylic. This study emphasizes on the total costing for dyeing, different types of fastness

properties (light, wash, rubbing and perspiration), dye uptake of the dyed samples. 0.5%, 1%,

2%, 3%, 4% red, blue and yellow shades were prepared for silk dyeing both by acid dye and

basic dye according to the dyeing method specified the dyes supplier. It is found that acid dyes

show higher dye uptake for red shade while basic dyes show better dye uptake for blue and

yellow shade. Color fastness tests on silk for acid dyes generally show better performance but

in case of color fastness to rubbing and perspiration tests both dyes show similar result. Dyeing

with basic dyes is comparatively economical than acid dyes as basic dyes are cheaper. As

fastness properties are given priority for fabric dyeing, in this case acid dyes are more suitable

for silk.

Keywords: Silk, dyeing, color fastness, shade%, costing.

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Table of content

Chapter 1: Introduction

1.1 General Introduction……………………….……………………………..

1.2 Objectives…………………………………………………………….…..

Chapter 2: Literature review

2.1 Introduction……………………………………………………………....

2.2 Microscopic structure of silk…………………………...…...…………....

2.3 Chemical composition of silk………………………………...…………..

2.4 Chemical structure of silk……………………………………...………...

2.5 Silk producing countries……………………………………………….....

2.6 Properties of silk…………………………………………………..……...

2.7 Uses of silk…………………………………………………………….....

2.8 Treatment and processing of silk………………………………………...

2.8.1 Pretreatment……………………………………………………………...

Degumming

Bleaching

2.9 Applicable dyes for silk…………………………………………………..

2.9.1 Acid dyes…………………………………………………………………

2.9.1.1 Common properties of acid dyes………………………………………....

2.9.1.2 Chemical structure of acid dyes……………………………………….....

2.9.1.3 Classes of acid dyes……………………………………………………....

2.9.1.4 Dyeing mechanism of acid dye on silk…………………………………..

2.9.2 Basic dyes…………..…………………………………………………....

2.9.2.1 Properties of basic dyes…………………………………………………..

2.9.2.2 Chemical structure of basic dyes…………………………………………

2.9.2.3 Dyeing mechanism of basic dye on silk…………………………….........

2.10 Kubelka Munk Equation ………………………………………………...

2.10.1 Color saturation measurement principle by spectrophotometer…...…..…

2.11 Conclusion……………………………………………………………….

Chapter 3: Materials and Methods

3.1 Introduction…………………………………………….………………...

3.2 Materials………………………………………………………………….

3.2.1 Fabric……………………………………………………………………..

3.2.2 Pretreatment materials……………………………………………………

3.2.2.1 Degumming Chemicals…………………………………………………..

3.2.3 Dyeing materials…………………………………………………………

3.2.3.1 Dyes………………………………………………………………………

3.2.3.2 Chemical and auxiliaries………………………………………………...

3.3 Color fastness testing chemicals……………………………….………...

3.4 Equipment……………………………………………………………….

3.5 Methods of silk dyeing…………………...................................................

3.5.1 Pretreatment of silk………………………………………………………

3.5.2 Silk dyeing with acid dyes…………………………………………...…..

3.5.3 Silk dyeing with basic dyes…………………………………………..….

3.6 Color fastness measurement……………………………………………..

3.6.1 Method and procedure…………………………………………………....

3.6.1.1 Color fastness to wash (ISO-105/ C06-C2S)………………………….….

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3.6.1.2 Color fastness to Rubbing (ISO-105/ X12)…………………………….....

3.6.1.3 Color fastness to perspiration (ISO-105/ E04)……………………….…...

3.6.1.4 Color fastness to light (ISO-105/ B02)……………………………….…..

3.6.2 Shade performance measurement…………………………………….…..

3.7 Conclusion…………………………………………………….……….....

Chapter 4: Result and Data

4.1 Introduction…………………………………………………………….....

4.2 Data on color strength………………………………….……………........

4.3 Result on color fastness………………………………….…………...…..

4.3.1 Color fastness to light …………………………………….……….…......

4.3.2 Color fastness to washing………………………………….…….…….....

4.3.3 Color fastness to Rubbing………………………………….…….…….....

4.3.4 Color fastness to perspiration ……………………………….….…….......

4.4 Costing……………………………………………………………………

4.4.1 Costing with acid dyes……………………………………..…………......

4.4.2 Costing with basic dyes……………………………………..………........

4.5 Conclusion ……………………………………………….….……...........

Chapter 5: Discussion

5.1 Introduction ………………………………………………….….….…….

5.2 Comparison on the basis of color strength………………………….…….

5.3 Comparison on the basis of color fastness……………………..................

5.4 Comparison on the basis of Costing ……………………………….……..

5.6 Comparison on basis of all parameters…………………………….…......

5.7 Conclusion…………………………………………………………..…….

Chapter 6: Conclusion

6.1 General conclusion…………………………………………………..…….

6.2 Recommendation………………………………………………….....…….

6.3 Limitations…………………………………………………………...……

References……………………………………………………….….…......

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Chapter 1: Introduction

1.1 General Introduction

Silk is an animal fiber, and therefore, like all animal fibers, is made of protein, due to this,

mechanism of dyeing silk is dependent mainly on free amino and carboxyl groups. Anionic

dyes such as acid, metal complex, reactive and selected direct dyes are suitable for dyeing

silk as it is slightly cationic with iso electric point at above pH 5 [1]. Silk offers a wide

coloration possibility covering almost the entire spectrum of colors. But the main objective

of coloration of a textile fibre is that the permanency of the color and should not allow

damage of natural abstract of fibre. This implies that it should not destroy its color during

processing following coloration and dyeing & subsequent useful life (i.e. washing, light,

rubbing, perspiration). So whatever dyestuff we use for silk dyeing it is very essential to

have permanency of that dyestuff [2].

In this study there are three major components which are silk fibre, acid dyes and basic

dyes. This report starts with some information on the silk fibre, about acid dyes, basic dyes

and progressed with mentioning the required material and equipment for silk dyeing from

pretreatment to performance evaluation.

Sericin, a group of soluble glycoprotein, normally present in the silk, which essential to be

removed from silk before dyeing it by degumming process to facilitate better luster and

color.

During dyeing, anionic dyestuffs namely acid and cationic dyes namely basic dyes form a

'Dye-Fibre' complex by electrostatic and hydrogen bonds [3]. This mechanism requires an

acidic medium to be activated. Exhaustion of dye from the bath requires a proper

controlling of the specified and recommended dyeing parameter. 0.5%, 1%, 2%, 3%, 4%

red, blue and yellow shade were prepared for silk dyeing both by acid dye and basic dye

according to the dyeing method specified the dyes supplier. Acid dyes were applied on silk

at 980C for 60 min while for basic dyes 800 C temperature for 40 min is maintained. Dyeing

procedures of basic dyes were almost similar to the dyeing procedures of acid dyes.

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Fixation treatment sometimes carried out on colored silk with a view to increase its fastness

behavior.

One of our main target is total costing evaluation for dyeing silk both by acid and basic

dyes. To evaluate the resistance to color fading especially to wash, rubbing, and

perspiration, light of acid and basic dyed silk fabrics is also our another target of this

project. Shade strength measurement using data color is also another technical aspect.

Comparison and decision is then made by mentioning that which one is better for silk from

the point of view of costing, fastness etc. Finally, our study is concluded by mentioning

some limitations of us about this project.

1.2 Objectives

The aim of the project is to find out the suitability of silk dyeing with acid and basic dyes from

aspect of economic and technical project of view.

To achieve this aim, the following objective were set:

i. To evaluate which dyeing method is economical for silk from acid and basic dyes.

ii. To find out the dye uptake of the dyed samples.

iii. To find out the dye that gives better performance (wash, rubbing, perspiration, light

fastness).

iv. To analyze different results, compare them graphically and finding out some

decisions from them regarding the preference a suitable dye on silk from acid and

basic dye.

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Chapter 2: Literature review

2.1 Introduction

Silk is called “Queen of fibres”, is a continuous protein fibre produced by silkworm so as to

form its cocoon. The silk. fibre is also produced by some spiders belonging to the Arachina

family. Unlike the silk worm’s fibre, the spider’s fibre cannot be commercially produced, and

therefore the silk fibre referred to in this work is the fibre coming from the silkworm. Most

historians agree that silk and sericulture the cultivation of silkworm had their origin in China

nearly 2500 BC. After finding this knowledge China kept it as a secret and held a monopoly in

the silk industry for nearly 4000 years. After this period, sericulture spread to Korea and Japan

and it also spread around the world.

Silk fibre is natural protein fibre. Unlike wool, silk contain very small amount of sulphur. There

are two main types of silkworm, mulberry silk also called ‘cultivated silk’ and wild silk of

which Tussah silk is the most important representative.

2.2 Microscopic structure of silk

Microscopic structure includes longitudinal and cross section. It means the fibre length,

fineness, crimp, color, &luster, surface contour, irregularities. Silk fibres are straight and

smooth. Raw silk fibre composed of two filaments, has elliptical shape under the microscopic.

Wild silk or tussah fiber has different appearance than cultivated silk. It is flattened, coarse,

thick & and broader fiber having fine wavy lines all across its surface where cultivated silk is

narrower fibre. Silk as is more crystalline as their molecules are highly oriented along the fibre

axis. As silk fibre from silk worm, is extruded out from the two glands, they are present as

triangular filaments, which are attached by gum named as sericin (Morton and Hearle, 1986).

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Fig. 2.1 Microscopic appearance of silk [4]

2.3 Chemical composition of silk

The strands of raw silk as they are unwound from the cocoon consist of the two silk filaments

mixed with sericin and other materials [5].

Fibroin 76%

Sericin 22%

Fat & wax 1.5%

Mineral salt 0.5%

2.4 Chemical structure of silk

Silk is comprised of a simple protein named as fibroin. Fibroin has a similar X-ray diffraction

pattern as Beta-keratin structure. The sulphur groups are very few. The main interaction

between the molecules are by hydrogen bonding and salt linkages. The X-ray diffraction

photography has shown that the silk in the crystalline part needs to be in fully extended chains.

Silk is made up of the amino acids GLY-SER-GLY-ALA-GLY and forms Beta pleated sheets.

The main amino acid is GLY or glycine. The three amino acids bond into a long chain that is

repeated and then the large amount of the acids for the Beta pleated sheets. This is the polymer

that is known commonly as silk. Silk is a natural polymer and it is found

in spiders and silkworms.

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Fig. 2.2 Chemical structure of silk fibroin [6]

2.5 Silk producing countries

Silk came from China to Persia, Korea and Japan. Up until the 13th century silk was only

available as an oriental import and only very wealthy people could afford it. In Europe,

southern Italy, while under Norman rule became an important center for breeding silkworms

and spinning silk. For a long time, Italy remained the leading silk country in Europe until

France expanded its silk weaving in the middle of the 17th century and surpassed Italy. China,

India, Uzbekistan, Brazil, Japan, Republic of Korea, Thailand, Vietnam, DPR Korea, Iran, etc.

are the major silk producer. [7]

2.6 Properties of silk

Physical properties of silk given below [8]

i. Color: The color of silk fiber could be yellow, brown, green or grey.

ii. Tensile strength: The strength is greatly affected by moisture; the wet strength of silk is

75 – 85%, which is higher than dry strength.

iii. Elongation at break: 20 -25% at break.

iv. Elastic recovery: Not so good.

v. Specific gravity: Specific gravity is 1.25 to 1.34.

vi. Moisture regain (R %): Standard moisture regain is 11% but can absorb up to 35%.

vii. Effect of heat: Silk will withstand at higher temperatures than wool. It will remain

unaffected for prolonged periods at 1400C. Silk decomposes at 1750C.

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viii. Effect of sun light: Sun light tends to encourage the decomposition of silk by

atmospheric oxygen.

ix. Luster: Bright.

Chemical properties of silk given below [8]

i. Effect of acids: The Fibroin of silk can be decomposed by strong acids into its constitute

amino acids. In moderate concentration, acids cause a contraction in silk. Dilute acids

do not attack silk under mild conditions.

ii. Effects of alkalis: Silk is less readily damaged by alkalis than wool. Weak alkalis such

as soap, borax and ammonia cause little appreciable damage. Silk dissolves in solutions

of concentrated caustic alkalis.

iii. Effect of organic solvent: Silk is insoluble in the dry-cleaning solvents in common use.

iv. Effects of Insects: Insect does not affect silk.

v. Effect of Mildew: Silk is affected by mildew slightly.

Here effect of acid, effect of alkali, effect of organic solvents, effect of moisture regains etc.

characteristics influence largely in dyeing of silk

2.7 Uses of silk

Silk has been the queen of fibres for centuries. It is used for luxury fabrics and high fashion

cloths and items but its durability extends its use to sports-wear and other contemporary

applications. Because of the unique characteristics and comfort properties, silk is used in both

apparels such as saris, dress, shirts, suits, pants, socks, etc. and home furnishings such as

upholstery fabrics, blankets, bed sheets etc. Moreover, as silk proteins amino acid composition

is close to that of the human skin, it is also used in biomedical applications such as medical

sutures, prosthetic arteries, etc. [9].

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2.8 Treatment and processing of silk

2.8.1 Pretreatment

Pretreatment means any treatment, which is done before actual (dyeing) process. For silk

fabric, Degumming/Scouring is generally carried out as preparatory process.

Degumming

Silk fibre contains approximately 20-25% Sericin gum. Sericin is a group of soluble

glycoprotein’s expressed in the middle silk gland of Bombyx mori. Silk emitted by the

silkworm consists mainly of two proteins, sericin and fibroin; fibroin being the structural center

of the silk, and sericin being the gum coating the fibres and allowing them to stick to each

other. The chemical composition of sericin is C30H40N10O16. The process of eliminating “Gum

(sericin)” from raw silk is known as degumming of silk. Degumming of silk involves mainly

the removal of sericin from the fibroin. Sericin is insoluble in water. It is comparatively easily

hydrolyzed whereby the long protein molecule of sericin is broken down into smaller fractions,

which are easily dispersed or solubilized in hot water. Hydrolysis of proteins can be carried out

by treatment with acids, alkalis and enzymes. Acids are non-specific and tend to

attack vigorously. Alkalis also attack both, sericin and fibroin. However, the variation in the

rate of hydrolysis is large enough to control the reaction. Removing the gum improves the

luster, color, hand, and texture of the silk.It is also known as silk scouring [10].

Bleaching

The silk being spun by silkworm contains natural colouring matter tinted with yellow, yellow

-green and brown pigments. During degumming the removal of sericin from the silk results in

dull white to lightly tinted material. Since some of the sericin is closely held by fibroin,

complete elimination of the colour by degumming is not possible. During bleaching these

natural colouring matters are decolorized /removed to produce pure white material. An efficient

bleaching process must ensure pure whiteness and level dyeing properties and non- degradation

of the material. The bleaching of silk is based on the use of either reducing agents or oxidizing

agents.

http://textilelearner.blogspot.com/search/label/Dyeing

http://textilelearner.blogspot.com/2012/03/degummingscouring-process-of-silk.html

http://textilelearner.blogspot.com/2012/03/degummingscouring-process-of-silk.html

http://textilelearner.blogspot.com/search/label/Bleaching

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2.9 Applicable dyes for silk

Normally acid dyes, reactive dyes, selected direct dyes are used for silk dyeing worldwide. But

at present basic dyes, vat dyes, metal-complex dyes etc. are also used.

2.9.1 Acid dyes

2.9.1.1 Common properties of acid dyes

Acid dyes are highly water soluble, and have better light fastness than basic dyes. They are

anionic in nature. They are suitable for wool, silk, polyamide and modified acrylics. These are

applied from a strongly acidic to neutral pH bath. These dyes combine with the fiber by

hydrogen bonds, Vander Waals forces or through ionic linkages. Acid dye is a sodium or

ammonium salt of a sulfuric, carboxylic or phenolic organic acid.

2.9.1.2 Chemical structure of acid dyes

These dyes are normally very complex in structure but have large aromatic molecules, having

a sulphonyl or amino group which makes them soluble in water. Most of the acid dyes belong

to following four main structural molecules: [11]

i. Anthraquinonetype: Many acid dyes are

synthesized from chemical intermediates which

form anthraquinone-like structures as their final

state.

Fig. 2.3. Anthraquinone derivatives

generally form blue dyes

ii. Azo dye type: The structure of azo dyes is based on

azobenzene, Ph-N=N−Ph and most are red in color.

Fig. 2.4 Azobenzene derivatives

generally form red dyes

http://textilelearner.blogspot.com/2012/01/acid-dyes-properties-of-acid-dyes.html

https://en.wikipedia.org/wiki/Salt_%28chemistry%29

https://en.wikipedia.org/wiki/Sulfuric_acid

https://en.wikipedia.org/wiki/Carboxylic_acid

https://en.wikipedia.org/wiki/Phenol

https://en.wikipedia.org/wiki/Organic_acid

https://en.wikipedia.org/wiki/Azobenzene

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iii. Premetallized acid dyes: Fall into two classes, 1:1

metal-complexes, in which one dye molecule is

complexed with one metal atom and the more

modern 1:2 metal complexes, in which one metal

atom is complexed with two dye molecules.

Fig. 2.5 Pre- Metalized Acid Dye

iv. Triphenylmethane type: Acid dyes having

structures related to triphenylmethane predominate

in the milling class of dye.They are mainly yellow

and green dyes.

Fig. 2.6 Triphenylmethane derivatives

generally form yellow or green dyes

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2.9.1.3 Classes of acid dyes

Acid Dyes fall into 3 subgroups or classes that describe their properties in the dyeing process.

The three classes are leveling, milling/super milling and pre-metallized.

Table 2.1: Characteristics of the various classes of acid dyes

Property Leveling Acid

Dyes

Milling/Super milling

Acid Dyes

Pre-metallized

Acid Dyes

Color Brightness Very Bright Bright Duller, more

earthy

Leveling tendency

(evenness of color) Very Good Ok Fair

Wash Fastness Good to 105˚F Very good to 120˚F Excellent to 140˚F

Light Fastness Good in most

cases Good in most cases Excellent

pH of dyebath 2-4 4-7 2-7

Additives for dyebath Acid,

Glauber's salt

Acid, Ammonium

Sulfate

Acid, Ammonium

Sulfate

Solubility in water 40-80 g/l 3-30 g/l Varies

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2.9.1.4 Dyeing mechanism of acid dye on silk

They contain sulphonic acid groups, which are usually present as sodium sulphonate salts.

This increase solubility in water, and give the dye molecules a colored anion.

Fig.2.7 colored anion formation of acid dye [2]

In an acidic solution, the -NH2 functionalities of the fibres are protonated to give a positive

charge: -NH3+. This charge interacts with the colored anion, allowing the formation of ionic

interactions. As well as this, Van-der-Waals bonds, dipolar bonds and hydrogen bonds are

formed between dye and fibre.

Fig. 2.8 Reaction of Silk with Acid Dye [12]

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2.9.2 Basic dyes

2.9.2.1 Common properties of basic dyes

The outstanding characteristics of the basic are brilliance and intensity of their colors. The

bright colors achieved from basic dyes do not usually occur with other dye classes. Many of

the basic dyes are sparingly soluble in water. The addition of glacial acetic acid helps to

dissolve the basic dye quickly in water. Basic dyes are readily soluble in alcohol or mentholated

spirit. The basic dyes are poor fastness to light and vary with regard to washing fastness from

poor to moderate. An important property of basic dyes is that they will combine with tannic

acid to form an insoluble compound provided mineral acid is absent. The wet fastness of the

basic dyes on protein fibers can also be improved by back tanning. The basic dyestuff will

combine with direct or Sulphur or some acid dyestuffs. So they cannot be used together in the

same bath. But basic dyestuffs are used in after treating cotton or other materials dyed with

direct colors [8].

2.9.2.2 Chemical structure of basic dyes

There are many dyes belonging to this class. The more important groups are described here

[13]

Group 1: Derivatives of triphenyl methane

Fig.2.9 Malachite Green

Group 2: Derivatives of thiazine

Fig. 2.10 Methylene Blue

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Group 3: Basic dyes containing oxazine group

Fig. 2.11 Meldola Blue

Group 4: Basic Dye containing azines

Fig. 2.12 Neutral Red

Group 5: Xanthene Basic Dyes

Fig.2.13 Rhodamine B

Group 6: Basic dyes containing azo groups

Fig. 2.14 Bismarck brown

2.9.2.3 Dyeing mechanism of basic dye on silk

Basic dye is a cationic dye. When it is introduced in an acidic medium it readily splits into

positive and negative parts. Here negative part does not show any color. Positive cationic part

is solely responsible for color production. Negative side of protein fiber comes closer to the

positive side of basic dye and forms bond. The bond formed this way yields bright color.

Fig: 2.15 Mechanism of basic dyeing on cellulose and protein fiber.

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2.10 Kubelka- Munk equation

𝐾

𝑆=(1 − 𝑅)2

2𝑅

Where,

R= Reflectance; K= Absorption Co-efficient; S= Scattering Co-efficient

2.10.1 Color saturation measurement principle by spectrophotometer

The sample is mounted on the integrated sphere. The light is passed through the lens to the

diffraction grating. When the diffracted light is fall on the detector, it measures the light

attributes and a microprocessor computes and give the results [14].

2.11 Conclusion

Silk is comprised of a simple protein named as fibroin. The main interaction between the

molecules are by hydrogen bonding and salt linkages. It can be decomposed by strong acid and

damaged by alkalis. It contains sericin in its structure that has to be removed by degumming

process. It is commonly dyed by acid & reactive dyes but we have researched silk with acid

and basic dyes. Acid dye is an anionic dyes and its anion is responsible for the coloration. Basic

dye is a cationic dye which is renowned for its brilliant color and intensity.

Fig. 2.15. Single beam spectrophotometer

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Chapter 3: Materials and Methods

3.1 Introduction

In this work has given importance to the materials and methods. This is reason of getting the

perfect result and output of the process from the project. Selection of material and methods is

essential for this project. This project has done based on the fabric, dyes, chemical and

auxiliaries. We have conducted our research with three major raw materials – silk fabric, acid

dye, basic dye followed by using different chemicals and auxiliaries, equipment in different

methods. In the pretreatment, dyeing, after treatment and dye uptake test and fastness tests need

to apply best method using suitable recipe and equipments. In this chapter silk dyeing with acid

and basic dyes for red, blue, yellow shade is done using appropriate procedure for achieving

perfect result.

3.2 Materials

3.2.1 Fabric

The silk fabric, that is collected by purchasing from The Sopura silk mills Ltd., Dhanmondi.

3.2.2 Pretreatment materials

3.2.2.1 Degumming Chemicals

Synthetic Detergent (Nonyl Phenol Ethoxylate), Soda ash, Sequestering agent (SQ-117CA),

Wetting agent (KS-10)

3.2.3 Dyeing material

Materials for Dyeing - Acid dyes, Basic dyes, chemical and auxiliaries.

3.2.3.1 Dyes

Red, blue and yellow colored acid and basic dyes were used for silk dyeing in powder form.

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Table 3.1 Sourcing of dyes for dyeing silk.

Name Brand Name Manufacturer Country Source Place of Source

Acid Dyes Erionyl Huntsman Thailand collected Swiss colors

Basic Dyes Taiacryl T& T Taiwan Collected Imperial

3.2.3.2 Chemicals & auxiliaries

For silk dyeing with acid dye, levelling agent, buffer is used (pH maintain 4.5) while levelling

agent, acid (pH maintain 4.5) is used for silk dyeing with basic dye. Soaping agent is used for

both but fixing agent is only for acid dyeing process.

Table 3.2 Sourcing of chemicals and auxiliaries for dyeing silk

Name Brand Name Manufacturer Country Source Place of source

Levelling Agent Albagal Huntsman Thailand collected Swiss colors

Buffer Albatex Huntsman Thailand collected Swiss Colors

Acetic Acid Neutra Tubingen Bangladesh collected Orient-Chem

Soaping Agent Eriopon OS Huntsman Germany collected Swiss colors

Fixing Agent Erional FRN Huntsman Thailand collected Swiss colors

Glauber salt Sateri Tubingen Bangladesh collected Orient- chem

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3.3 Color fastness testing chemicals

Name Process

-ECE (Detergent),

- Soda ash

- Sodium per borate

washing fastness

- L-Histadine mono-hydrochloridemonohydrate

- Disodiumhydrogenorthophosphate dehydrate

- Sodium Chloride

- HCl

Perspiration fastness

3.4 Equipment

There are different types of equipment needed for pretreatment, dyeing and testing silk.

Table 3.3 Equipment required for dyeing and testing silk

Name Brand name Steps

Lab Dyeing m/c IR Dyer Degumming, coloration

CCMS/ Data color 650 Shade strength,dye up-take

Washing machine Labtec Wash Fastness Test

Crock meter Crockmaster Rubbing Fastness Test

Xenon light box Q-sun Light Fastness Test

Incubator Labtec Perspiration fastness test

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3.5 Methods of silk dyeing

3.5.1 Pretreatment of silk

Degumming of silk with synthetic detergents (Non-ionic product like Nonyl phenol

ethoxylated) is carried out as pretreatment of silk.

Recipe for silk degumming with synthetic detergent

Synthetic Detergent (Nonyl Phenol Ethoxylate) : 3g/l

Wetting agent (KS-10) : 2.5 g/L

Sequestering agent (SQ-117CA) : 0.5 g/l

Soda ash : 2 g/l

pH : 11.5

Water : 27.9cc

M: L : 1:10

Temperature : 950 C

Time : 40min

Stock solution: 10 % For Wetting Agent

10 % For Sequestering agent

20 % For Soda Ash

Procedure of degumming

The bath was set with substrate at room temperature and KS-10 (wetting agent), SQ-117CA

(Sequestering agent) and detergent was added to it. Then temperature was raised at 2°C /min

to 80°C and then pH was maintained to 11.5 by adding soda ash. After that, temperature was

raised to 95°C and ran for 40 minutes for optimum removal of sericin gum. The bath was cooled

down to 60°C and then the bath was dropped. At last, it was washed with warm and cold water

successively.

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Process curve of degumming

Fig 3.1 process curve of degumming of silk by detergent

3.5.2 Silk dyeing with acid dyes

In this project, total 15 samples were dyed with Acid dye by lab dyeing machine (IR Dyer).

5 samples for 0.5%, 1%, 2%, 3%, 4% Red shade,

5 samples for 0.5%, 1%, 2%, 3%, 4% Blue shade,

5 samples for 0.5%, 1%, 2%, 3%, 4% Yellow shade.

Recipe for acid dye

For 4gm Silk fabric sample -

Acid Dyes (Erionyl) - 3% owf)

Albatex AB 45 (Buffer to maintain pH 4.5) - 1.0 g/l

Albagal SET (Levelling Agent) - 1.0 %

M: L - 1:10

Temperature - 98°C

Time - 60min

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Dyeing procedure of silk with acid dye

At first dye solution was prepared. Then dye paste was prepared by adding water with dyes,

then hot water was added with stirring to produce desirable dye solution.

Albagal SET (Leveling agent) was taken into the dye pots. Dye solution for shade 0.5%, 1%,

2%, 3%, 4% respectively were added into the dye pots. Then remaining water was added. After

that Albatex AB 45 (buffer solution) was added to maintain pH 4.5. At last Silk fabric samples

weretaken into the pots. Dye bath was prepared at 500 C temperature. The dye pots were placed

in the dye bath and ran the bath for 10 minute at 500C. Temperature was raised to 980 C at 10

C/ min rate. Dye bath was run for 60 min. Then bath was dropped at 60°C at 1.5oC /min rate.

Dyeing curve of silk with acid dye

Fig 3.2 dyeing curve of acid dye on silk

After treatment

Dyed silk samples were rinsed with cold water. After that they were washed at 80°C for 5 min

with soaping agent Eriopon OS 1.0 g/l. Then the samples were rinsed again in cold water.

Fixing was done with Erional FRN 3.0% at pH 4.5 (with Albatex AB 45) at 80°C for 30

minutes. Then they were rinsed again with cold water. At last the samples were dried in dryer.

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3.5.3 Silk dyeing with basic dyes

In this project, total 15 samples were dyed with Basic dye by lab dyeing machine (IR Dyer).

5 samples for 0.5%, 1%, 2%, 3%, 4% Red shade,

5 samples for 0.5%, 1%, 2%, 3%, 4% Blue shade,

5 samples for 0.5%, 1%, 2%, 3%, 4% Yellow shade.

Recipe for basic dye

For 4gm Silk fabric sample-

Basic dyes (Taiacryl) - 3% (owf)

Albagal SET (Leveling Agent) - 1 %

Glauber Salt (Na2SO4.10 H2O) - 10 g/l

Acetic Acid (pH= 4.5) - 0.07 ml

M: L - 1:10

Temperature - 80°C

Time - 40 Min

Dyeing procedure of silk with basic dye

At first dye solution was prepared. Then dye paste was prepared by adding water with dyes,

then hot water was added with stirring to produce desirable dye solution.

Albagal SET (Leveling agent) was then taken into the dye pots. Then Glauber salt (Na2SO4.10

H2O) was added. Dye solution for shade 0.5%, 1%, 2%, 3%, 4% respectively were added into

the dye pots. Then remaining water was added. After that acetic acid solution was added to

maintain pH 4.5. At last Silk fabric samples were taken into the pots. Dye bath was prepared

at 400 C temperature. The dye pots were placed in the dye bath and ran the bath for 10 minute

at 400C. Temperature was raised to 800 C at 1.50 C/ min rate. Dye bath was run for 40 min.

Then bath was dropped at 60°C at 1.5oC /min rate.

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Dyeing curve of silk with basic dye

Fig 3.3 dyeing curve of basic dye on silk

After treatment

Dyed silk samples were rinsed with cold water. After that, hot wash wass given at 80°C for 5

min with a soaping agent Eriopon OS 1.0 g/l. Then the samples were rinsed again in cold water.

At last the samples were dried in dryer.

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3.6 Color fastness measurement

In this project, we have assessed total 4 types of color fatness test: color fastness to wash, color

fastness to rubbing (dry and wet), color fastness to perspiration (acidic and alkaline), Color

fastness to light.

3.6.1 Method and procedure

3.6.1.1 Color fastness to wash (ISO-105/ C06-C2S)

Color fastness to wash was measured with ISO-105/ C06-C2S method using 10 cm×4 cm dyed

silk sample and multifibre fabric with the washing recipe:

ECE (Detergent) - 3 g/l

Soda ash (pH 11) - 2 g/l

Sodium perborate (NaBO3.10 H2O) - 1 g/l

M: L - 1:10

Washing temperature - 600c

Washing time - 30 Min

Test procedure

First condition the sample fabric for 4–6 hours. Then the sample fabric and multifibre fabric

are cut according to required size (10cm×4 cm) and the multifibre fabric is attached with the

sample fabric by sewing to make composite sample. After that a solution of 3gm/L ECE

detergent and 1gm/L sodium perborate is made. Soda ash is used to maintain pH 11. Then the

composite sample is washed for 30minutes at 600C. In this method, 10 stainless steel ball were

used during washing to provide mechanical action each having diameter of 0.6 cm and weight

of 1 gm. Finally, the composite sample is dried not exceeding 600C and detach the multifibre

fabric.

Color change and staining is then rated by grey scale.

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3.6.1.2 Color fastness to Rubbing (ISO-105/ X12)

The resistance of color of dyed silk to the action of rubbing (dry and wet) was evaluated with

ISO-105/ X12 method.

Sample preparation

Silk sample fabric : 14cm×5 cm

Cotton rubbing cloth : 5cm×5 cm

Requirements

Dry and wet (100%) silk sample fabric.

Test Procedure

First the sample is put in the crockmaster clamp. Then rubbing dry cloth is placed at the finger

for dry rubbing test. OK button is clicked to run the machine 10cycle / 10seconds. After that

the white rubbing test cloth is removed. Same procedure used for wet rubbing test. The wet

rubbing cloth is dried not more than 600C.

Evaluating is done with grey scale with a rating of 1-5.

3.6.1.3 Color fastness to perspiration (ISO-105/ E04)

The resistance of color to the action of perspiration (acidic and alkaline) was measured with

ISO-105/ E04 method.

Sample preparation

Silk sample fabric : 10cm×4 cm

Cotton perspiration fabric : 10cm×4 cm

Required chemicals

i. L-histadine mono-hydrochloric hydrate - 0.5 gm/L

ii. Di-Sodium Hydrogen ortho phosphate di hydrate - 2.5 (alkaline) and 2.2gm/L (acidic)

iii. Sodium Chloride -5.0 gm/L

iv. pH (adjusted with 0.1N NaOH) -8 (alkaline) and 5.5 (acidic)

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Test Procedure

At first two silk sample and cotton perspiration fabric is cut into 10x4cm and then attached

these. The composite sample is immersed in the acid and alkali solution (individually). Then

placed it in a preheated perspirometer acrylic glass plate under the pressure of 12.5kpa and

placed the perspirometer in the oven incubator at 380C for 4 hours. After that the perspirometer

is removed from the oven and remove the composite sample. Finally dried not exceeding 600C

and detach the cotton perspiration fabric from silk sample.

Evaluating is done with grey scale.

3.6.1.4 Color fastness to light (ISO-105/ B02)

The resistance to fading of dyed silk when exposed to Xenon arc fading lamp light was

measured using ISO- 105/ B02 method by exposing the half portion of the sample for 20 hours.

Test Procedure

The silk sample is cut according to the temple size and attached to the temple in a half covered

manner along with standard dyed wool. The samples are then mounted on light fastness tester.

Time and light is set. Half portion of the sample is exposed to Xenon arc fading lamp light for

20 hours. Finally, sample is taken out.

Evaluating is done with Blue scale with a rating of 1-8.

3.6.2 Shade performance measurement

Using data color, in this project, we have measured Absorption value (K/S) of 15 acid dyed

silk samples and 15 basic dyed silk sample.

3.7 Conclusion

This project work is done by two dyeing processes for silk fabric using acid and basic dyes

with suitable chemical and auxiliaries, equipment. Silk dyeing with basic dyes is not yet a

widely used method. For this enough information about silk dyeing with basic dyes is not

found. But tried to use the best method, materials and procedure for silk dyeing with both dyes.

Basic dyes can also be used for silk dyeing if the fastness properties can be increased by

mordanting.

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Chapter 4: Results and Data

4.1 Introduction

In this chapter we have discussed about the result and output in details. This is very important

for any type of work because of getting the overview of the work from this section. In this work

the result and data are shown perfectly and smoothly so that the output can be realized easily.

Every point of this output is given importance. The prime focus of this chapter is to evaluate

color strength, colorfastness and costing of acid and basic dyed silk sample. For evaluation the

result of data and image of sample for every process, color strength, color fastness and costing

is added.

4.2 Data on color strength

a) 0.5% b) 1% c) 2% d) 3% e) 4%

Fig 4.1 k/s value of acid dyed silk sample (red)

a) 0.5% b) 1% c) 2% d) 3% e) 4%

Fig 4.2 k/s value of basic dyed silk sample (red)

k/s value from fig 4.1 and fig 4.2 is used in table 4.1

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Table 4.1 Comparison of K/S value of acid and basic dyed silk samples (Red shade)

Red

K/S value (630 nm)

0.5% conc.

(owf)

1% conc.

(owf)

2% conc.

(owf)

3% conc.

(owf)

4% conc.

(owf)

Acid dye 1.61 2.97 5.99 9.52 11.45

Basic dye 1.41 2.13 3.71 6.48 8.15

a) 0.5% b) 1% c) 2% d) 3% e) 4%

Fig 4.3 k/s value of acid dyed silk sample (Blue shade)

a) 0.5% b) 1% c) 2% d) 3% e) 4%

Fig 4.4 k/s value of basic dyed silk sample (blue)


Table 4.2 Comparison of K/S value of acid and basic dyed silk samples (Blue shade)

Blue

K/S value (630 nm)

0.5% conc.

(owf)

1% conc.

(owf)

2% conc.

(owf)

3% conc.

(owf)

4% conc.

(owf)

Acid dye 1.21 2.18 4.45 6.85 8.93

Basic dye 9.23 15.35 19.66 21.33 20.89

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a) 0.5% b) 1% c) 2% d) 3% e) 4%

Fig 4.5 k/s value of acid dyed silk sample (Yellow shade)

a) 0.5% b) 1% c) 2% d) 3% e) 4%

Fig 4.6 k/s value of acid dyed silk sample (Yellow shade


Table 4.3 Comparison of K/S value of acid and basic dyed silk samples (Yellow shade)

Yellow

K/S value (440 nm)

0.5% conc.

(owf)

0.5% conc.

(owf)

0.5% conc.

(owf)

0.5% conc.

(owf)

0.5% conc.

(owf)

Acid dye 1.68 1.68 1.68 1.68 1.68

Basic dye 5.08 7.89 13.59 19.7 18.58

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4.3 Result on Color fastness

4.3.1 Color fastness to light

Table 4.4 Color fastness to light for acid and basic dyed silk fabric (Red shade)

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Table 4.5 Color fastness to light for acid and basic dyed silk fabric (Blue shade)

Table 4.4 and 4.5 shows that light fastness for red and blue shade is average-good for acid dyes

and moderate for basic dyes.

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Table 4.6 Color fastness to light for acid and basic dyed silk fabric (Yellow shade)

Table 4.6 shows that light fastness for yellow shade is good for acid dyes and average for basic

dyes.

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4.3.2 Color fastness to Washing

(Red 0.50%)

(Red 1.00%)

(Red 2.00%)

(Red 3.00%)

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(Red 4.00%)

(Red 2.00%)

(Red 0.50%)

(Red 1.00%)

Fig 4.7 Color fastness to light for acid dyed silk fabric (Red shade)

Fig 4.7 shows that wash fastness for acid dye red shade is moderate-average.

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(Red 4.00%)

(Red 3.00%)

(Blue 0.50%)

(Blue 1.00%)

Fig 4.8 Color fastness to light for basic dyed silk fabric (Red shade)

Fig 4.8 shows that wash fastness for basic dye red shade is poor-moderate.

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(Blue 4.00%)

(Blue 3.00%)

(Blue 2.00%)

Fig 4.9 Color fastness to light for acid dyed silk fabric (Blue shade)

Fig 4.9 shows that wash fastness for acid dye blue shade is good.

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(Blue 3.00%)

(Blue 2.00%)

(Blue 1.00%)

(Blue 0.50%)

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(Blue 4.00%)

(Yellow 2.00%)

(Yellow 1.00%)

(Yellow 0.50%)

Fig 4.10 Color fastness to light for basic dyed silk fabric (Blue shade)

Fig 4.10 shows that wash fastness for basic dye blue shade is poor-moderate.

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(Yellow 4.00%)

(Yellow 3.00%)

(Yellow 1.00%)

(Yellow 0.50%)

Fig 4.11 Color fastness to light for acid dyed silk fabric (Yellow shade)

Fig 4.11 shows that wash fastness for acid dye yellow shade is good-excellent.

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(Yellow 3.00%)

(Yellow 2.00%)

(Yellow 4.00%)

Fig 4.12 Color fastness to light for Basic dyed silk fabric (Yellow shade)

Fig 4.12 shows that wash fastness for basic dye yellow shade is average-good.

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4.3.3 Color fastness to rubbing

Acid dyed red sample 2.00% shade




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Fig 4.13 Color fastness to rubbing(staining) for acid dyed silk fabric (Red shade)

Fig 4.13 shows that dry rub fastness for acid dye red shade is excellent and wet rub fastness is

good-excellent.


Basic dyed red sample 2.00% shade



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Fig 4.14 Color fastness to rubbing (staining) for Basic dyed silk fabric (Red shade)

Fig 4.13 shows that dry rub fastness for basic dye red shade is excellent and wet rub fastness

is good.



Acid dyed blue sample 0.50% shade


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Fig 4.15 Color fastness to rubbing(staining) for acid dyed silk fabric (blue shade)

Fig 4.15 shows that dry rub fastness for acid dye blue shade is excellent and wet rub fastness

is good-excellent.



Basic dyed blue sample 0.50% shade


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Fig 4.16 Color fastness to rubbing(staining) for basic dyed silk fabric (Blue shade)


Color fastness to rubbing (Basic dyed blue sample 1.00% shade)



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Fig 4.16 shows that dry rub fastness for basic dye blue shade is average-good and wet rub

fastness is moderate-average.

Acid dyed yellow sample 0.50% shade




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Fig 4.17 Color fastness to rubbing (staining) for acid dyed silk fabric (Yellow shade)

Fig 4.13 shows that dry and wet rub fastness for acid dye yellow shade is excellent.


Basic dyed yellow sample 0.50% shade



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Fig 4.18 Color fastness to rubbing(staining) for basic dyed silk fabric (Yellow shade)

Fig 4.18 shows that dry rub fastness for basic dye yellow shade is excellent and wet rub

fastness is good-excellent.


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4.3.4 Color fastness to Perspiration

Acid dyed red sample for 0.50% shade


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Fig 4.19 Color fastness to perspiration for acid dyed silk fabric (Red shade)

Fig 4.19 shows that fastness to perspiration for acid dye red shade is excellent.


Basic dyed red sample for 0.50% shade

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Fig 4.20 Color fastness to perspiration for Basic dyed silk fabric (Red shade)

Fig 4.20 shows that fastness to perspiration for basic dye red shade is good-excellent.



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Acid dyed blue sample for 1.00% shade


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Fig 4.21 Color fastness to perspiration for acid dyed silk fabric (Blue shade)

Fig 4.21 shows that fastness to perspiration for acid dye blue shade is excellent.

Basic dyed blue sample for 0.50% shade

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Fig 4.22 Color fastness to perspiration for Basic dyed silk fabric (Blue shade)

Fig 4.22 shows that fastness to perspiration for basic dye blue shade is average-excellent for

acidic condition and excellent for alkaline condition



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Acid dyed yellow sample for 0.50% shade


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Fig 4.23 Color fastness to perspiration for acid dyed silk fabric (Yellow shade)

Fig 4.23 shows that fastness to perspiration for acid dye yellow shade is excellent.

Basic dyed yellow sample for 0.50% shade


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Fig 4.24 Color fastness to perspiration for basic dyed silk fabric (Yellow shade)

Fig 4.23 shows that fastness to perspiration for basic dye yellow shade is excellent.



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4.4 Costing

4.4.1 Costing for silk dyeing acid ayes (Red, Blue, yellow shade)

In the silk dyeing with Acid Dyes, stock solution for Acid Dyes is 1%, sample weight is 4gm,

leveling agent is 1% & stock solution is 10%, Buffer is 1 g/l & stock solution is 10%. For

dyeing M: L is 1:10 but for after treatment M: L is 1:20.

For 0.5% shade-

Ingredient Quantity (gm) Rate of Price (per /kg) Cost(USD)

Acid Dyes 0.02 USD 20 (20×78=1560tk) 0.0004

Levelling Agent (Albagal Set) 0.04 USD 4.50 (4.50×78=351tk) 0.00018

Buffer (Albatex AB 45) 0.1 USD 2.20 (2.20×78=171.6tk) 0.00022

Soaping Agent (Eriopon OS) 0.08 USD 4.50 (4.50×78=351tk) 0.00036

Fixing Agent (Erional FRN) 1.2 USD 4.50 (4.50×78=351tk) 0.0054

Total 0.00656

For 1.00 % shade-


Acid Dyes 0.04 USD 20(20×78=1560tk) 0.0008

Levelling Agent (Albagal Set) 0.04 USD 4.50(4.50×78=351tk) 0.00018

Buffer (Albatex AB 45) 0.1 USD 2.20(2.20×78=171.6tk) 0.00022

Soaping Agent (Eriopon OS) 0.08 USD 4.50(4.50×78=351tk) 0.00036

Fixing Agent (Erional FRN) 1.2 USD 4.50(4.50×78=351tk) 0.0054

Total 0.00696

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For 2.00 % shade-


Acid Dyes 0.08 USD 20(20×78=1560tk) 0.0016





Total 0.00776

For 3.00 % shade-


Acid Dyes 0.12 USD 20(20×78=1560tk) 0.0024





Total 0.00856

For 4.00 % shade-


Acid Dyes 0.16 USD 20(20×78=1560tk) 0.0032





Total 0.00936

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4.4.2 Silk Dyeing with basic dyes (Red, Blue, yellow shade)

In the silk dyeing with Basic Dyes, stock solution = 1%, sample weight = 4gm, Levelling agent

=1g/l& stock solution=10%, Glauber salt =10g/l & stock solution=20%, and for dyeing M: L

= 1:10 but for after treatment M: L=1:20.

For 0.50 % shade-

Ingredient Quantity (gm) Rate of Price (per /kg) Cost

Basic Dyes 0.02 USD 20(20×78=1560tk) 0.0004


Glauber salt 0.02 USD 2.20(2.20×78=171.6tk) 0.000044

Acetic Acid 0.12 USD 4.50(4.50×78=351tk) 0.00054


Total 0.001524

For 1.00 % shade-


Basic Dyes 0.04 USD 20(20×78=1560tk) 0.0008





Total 0.001924

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For 2.00 % shade-


Basic Dyes 0.08 USD 20(20×78=1560tk) 0.0016





Total 0.002724

For 3.00 % shade-


Basic Dyes 0.12 USD 20(20×78=1560tk) 0.0024





Total 0.003524

For 4.00 % shade-


Basic Dyes 0.16 USD 20(20×78=1560tk) 0.0032





Total 0.004324

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4.5 Conclusion

The project work is done to get best result in this project for silk dyeing with acid and basic

dyes. The result is based on comparison of cost effectiveness of two dyes and for this showed

the color strength and color fastness test results by using image of sample with suitable size.

As a result, it could be able to indicate the suitable dyes for silk dyeing both from the point of

view of cost and effectiveness. This project work is done for small amount of samples so

costing is calculated here for 4 g sample but in next chapter discussed the costing for per kg of

silk.

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Chapter 5: Discussion

5.1 Introduction

This is the chapter where given importance on discussion based on the result of the project

what are done. Discussion is very essential as what is output known by this part. Comparing

criteria of this project work are shade strength, color fastness properties and last one is costing

between acid and basic dyed silk fabric. The final output of this project based on these three

criteria is discussed in this chapter. The shade strength and color fastness results are discussed

by using chart so that can be easily compare among both dyes and their performances.

5.2 Comparison on the basis of color strength

Fig. 5.1 Bar diagram of K/S value of acid and basic dyed silk samples (Red shade)

Figure 5.1 shows the effect of dye concentration on dye uptake. Dye uptake increased

progressively as colorant concentration increased. With increasing concentration, more dye

transferred to fabric and the depth of color became stronger. From the above bar diagram, it is

clear that the acid dyes show higher dye take-up than basic dyes at higher dye concentrations

for red color.

0

2

4

6

8

10

12

14

0.50% 1% 2% 3% 4%

Effect of dye concentration on dye take up (Red)

Acid dye Basic dye

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Fig. 5.2. Bar diagram of K/S value of acid and basic dyed silk samples (Blue shade)




clear that the basic dyes show higher dye take-up than acid dyes at higher dye concentrations

for blue color.

Fig. 5.3 Bar diagram of K/S value of acid and basic dyed silk samples (Yellow shade)

0

5

10

15

20

25

0.50% 1% 2% 3% 4%

Effect of dye concentration on dye take up (Blue)

Acid dye Basic dye

0

5

10

15

20

25

0.50% 1% 2% 3% 4%

Effect of dye concentration on dye take up (Yellow)

Acid dye Basic dye

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clear that the basic dyes show higher dye take-up than acid dyes at higher dye concentrations

for yellow color.

5.3 Comparison on the basis of color fastness

Fig 5.4 Color fastness to light (Blue scale value)

From the fig 5.4 it is found that, acid dyed silk sample shows better color fastness to light than

basic dyed silk. It is also visible that fastness to yellow color for basic dyes is comparatively

better than red and blue color for basic dyes.

0

1

2

3

4

5

6

Red Blue Yellow

Acid Dye

Basic Dye

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Fig 5.5 Color Fastness to Washing (Grey scale value for color change)

From figure 5.5, it is clear that, acid dyed silk sample shows better resistance color fading

against the action of washing. It is also visible that fastness to yellow color for basic dyes is

comparatively better than red and blue color for basic dyes.

Fig 5.6 Color Fastness to Washing (Grey scale value for staining)

From figure 5.6, it is noticed that, acid dyed silk sample shows slightly better performance in

case of staining than basic dyed silk during washing (for red color).

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Red Blue Yellow

Acid Dyes

Basic Dyes

0

1

2

3

4

5

6

Acetate Cotton Polyamide Polyester Acrylic Wool

Acid Dyes (Red)

Basic Dyes (Red)

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From figure 5.7, it is noticed that, acid dyed silk sample shows very much better performance

in case of staining than basic dyed silk during washing (for blue color).


From figure 5.8, it is noticed that, acid dyed silk sample shows much better performance in

case of staining than basic dyed silk during washing (for blue color).

0

1

2

3

4

5

6


Acid Dyes (Blue)

Basic Dyes (Blue)

0

1

2

3

4

5

6


Acid Dyes

(Yellow)

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Fig 5.9 Color Fastness to Rubbing (Grey scale value for dry rub)

Figure 5.9 represents that, staining performance of acid dyed silk is almost same as the basic

dyed silk fabric in case of red and yellow shade for dry rubbing while in case of blue shade,

staining performance of acid dyed silk is comparatively better than basic dyed silk.

Fig 5.10 Color Fastness to Rubbing (Grey scale value for wet rub)

Figure 5.10 represents that, staining performance of acid dyed silk is better than the basic dyed

silk fabric in case of wet rubbing.

0

1

2

3

4

5

6

Red Blue Yellow

Acid Dyes

Basic Dyes

0

1

2

3

4

5

6

Red Blue Yellow

Acid Dyes

Basic Dyes

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Fig 5.11 Color Fastness to Perspiration (Grey scale value (color change) for acidic solution)

Figure 5.11 represents that, resistance to color fading against the action of acidic perspiration

of acid dyed silk is much better than the basic dyed silk fabric in case of red and blue shade

while in case of yellow shade, color fastness of acid dyed silk is almost same as the basic dyed

silk.

Fig 5.12 Color Fastness to Perspiration (Grey scale value (color change) for alkaline solution)

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5

5.1

Red Blue Yellow

Acid Dyes

Basic Dyes

4.2

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5

5.1

Red Blue Yellow

Acid Dyes

Basic Dyes

82 | P a g e

Figure 5.12 represents that, resistance to color fading against the action of alkaline perspiration

of acid dyed silk is much better than the basic dyed silk fabric in case of red shade while in

case of blue and yellow shade, color fastness of acid dyed silk is almost same as the basic dyed

silk.

Fig 5.13 Color Fastness to Perspiration (Grey scale value (color staining) for acidic solution)

Figure 5.13 represents that, staining performance of acid dyed silk is very much better than the

basic dyed silk fabric in case of acidic perspiration.

0

1

2

3

4

5

6

Red Blue Yellow

Acid Dyes

Basic Dyes

83 | P a g e

Fig 5.14 Color Fastness to perspiration (Grey scale value (color staining) for alkaline

solution)

Figure 5.14 represents that, staining performance of acid dyed silk is very much better than the

basic dyed silk fabric in case of acidic perspiration.

5.4 Comparison on the basis of costing

Fig 5.15 Total cost in USD for 1kg silk fabric dyeing

0

1

2

3

4

5

6

Red Blue Yellow

Acid Dyes

Basic Dyes

0

0.5

1

1.5

2

2.5

0.50% 1.00% 2.00% 3.00% 4.00%

Acid Dyes

Basic Dyes

84 | P a g e

Table 5.1 Costing for 1kg silk fabric dyeing by acid and basic dyes

The above data represents that silk dyeing with acid dyes is costlier than dyeing with basic

dyes. One of the main reason behind this is the use of fixing agent during silk dyeing with acid

dyes while no fixing agent is used in case of basic dye as it was recommended by basic dyes

suppliers. It is also clear that the cost increases with the increase of dye concentration.

5.6 Comparison on basis of all parameters

For the ease of understanding all the results and assessments are summarized below:

Parameters Comparison

Dye uptake

Acid dyes show higher dye take up than basic

dyes in case of red shade but basic dye shows

higher dye take up in case of blue and yellow

shade.

Light Fastness (ISO-105/B02) Acid dyes show better performance than basic

dyes.

Wash fastness Test (ISO-105/C06-C2S)

Color Change

Color Staining

Acid dyes show better performance than basic

dyes.

Dyes

Total cost in USD for 1 kg fabric dyeing

0.5% conc.

(owf)

1% conc.

(owf)

2% conc.

(owf)

3% conc.

(owf)

4% conc.

(owf)

Acid dye

(Red, Blue, Yellow) 1.64 1.74 1.94 2.14 2.34

Basic dye

(Red, Blue, Yellow) 0.381 0.481 0.681 0.881 1.081

85 | P a g e

Rubbing Test (ISO-105 X12)

Both acid and basic dyes show better

performance though acid dye shows slightly

better performance than basic dye.

Perspiration Test (ISO-105/E04)

Color change

Color staining

Both acid and basic dyes show better

performance in case of fading but for staining

acid dye’s performance is better.

Cost Dyeing with basic dye is economical than acid

dye as cost of basic dyes are less.

5.7 Conclusion

In this chapter the output of the research is clearly shown by bar diagram for every dyes, shade

percentage and for color fastness to washing, rubbing, perspiration. From these bar diagram

finds out that basic dyeing cost is less but the fastness properties of acid dyes are good. So as

the fastness properties are very important for dyeing, acid dyes are suitable for silk dyeing in

overall point of view.

86 | P a g e

Chapter 6: Conclusion

6.1 General conclusion

This project work is done to find out suitable cost effective dyes for dyeing silk among acid

dyes and basic dyes. During this project work silk is dyed with three different color (red, blue,

yellow) for 5 shade (0.5%, 1%, 2%, 3 %, 4%). Then color strength value is taken by Data Color

and fastness tests (light, wash, rubbing, perspiration) are done to compare the dyeing

performance and find out the result of the project. It is found that acid dyes show higher dye

uptake for red shade while basic dyes show better dye uptake for blue and yellow shade. Color

fastness tests on silk for acid dyes generally show better performance but in case of color

fastness to rubbing and perspiration tests both dyes show similar result. Dyeing with basic dyes

is comparatively economical than acid dyes as basic dyes are cheaper. As fastness properties

are given priority for fabric dyeing, in this case acid dyes are more suitable for silk dyeing.

6.2 Recommendation

The project work suggests that silk dyeing with acid dyes is more suitable from the

point of view of fastness properties and dye uptake as the data shows good result for

acid dyes.

On the other hand, basic dyes are suitable from economical point of view as basic dyes

cost is less than acid dyes.

The fastness properties of basic dyes can be increased by mordanting in further

research.

In future apply basic dye along with acid dye can be applied through vigorous research

and process development.

6.3 Limitations

Silk dyeing with basic dyes is not yet widely used method. For this enough information

about silk dyeing with basic dyes is not found.

As the project work is done in sample dyeing process, the solution amount was very

little so it was difficult to maintain the perfect amount of chemical solution.

87 | P a g e

It was critical to maintain exact pH during the dyeing process for both acid dyes and

basic dyes.

Sometimes dye powder did not mix uniformly, that’s why experienced some dyeing

spots on fabric and rejected those.

The dyes were collected from two different companies, for this there is some shade

matching problem of same color dyes.

In case of color fastness to rubbing test, cotton rubbing cloth is not suitable for silk

rubbing. So rubbing result is not accurate.

The samples are dried in normal dryer instead of stenter. Use of stenter may further

increase the performance.

88 | P a g e

References

[1] J. Gordon Cook, Handbook of textile fibres.

[2] Md. Koushic Uddin, A comparative study on silk dyeing with acid dye and reactive dye ,

Journal of IJET

[3] Textile Testing Laboratory, CSTRI, Central Silk Board, Varanasi.

[4] http://www.natursint.com/SILKSKIN_PRESENTATION.pdf

[5] http://www.slideshare.net/YousufTE/natural-textile-fibers-cotton-jute-silk-wool

[6] https://www.tes.com/lessons/xgx8VfOSYlkF4w/silk-fibroin

[7] http://www.silkfabric.info/history/history-of-silk.html

[8] http://textilelearner.blogspot.com/2011/08/characteristics-of-silk-fabrics_5368.html

[9] http://www.yourarticlelibrary.com/zoology/silk-properties-and-uses-of-silk/23816/

[10] Bangladesh Textile Today Blog

[11] WWW.Wikipedia.com/acid dye

[12] A D Broadbent(2001), Basic principles of textile coloration.

[13] E R Trotman, Dyeing and chemical technology of textile fibre.

[14] Introduction to the physical basis and measurement of color .

[15] http://textilelearner.blogspot.com/2011/07/bleaching-process-of-silk-

silk.html#ixzz3voYqBCdU

http://www.natursint.com/SILKSKIN_PRESENTATION.pdf

http://www.slideshare.net/YousufTE/natural-textile-fibers-cotton-jute-silk-wool

https://www.tes.com/lessons/xgx8VfOSYlkF4w/silk-fibroin

http://textilelearner.blogspot.com/2011/08/characteristics-of-silk-fabrics_5368.html

http://www.yourarticlelibrary.com/zoology/silk-properties-and-uses-of-silk/23816/

http://www.textiletoday.com.bd/silk-and-its-degumming-process/

http://www.wikipedia.com/acid

http://textilelearner.blogspot.com/2011/07/bleaching-process-of-silk-silk.html#ixzz3voYqBCdU

http://textilelearner.blogspot.com/2011/07/bleaching-process-of-silk-silk.html#ixzz3voYqBCdU

Date post:	13-Apr-2017
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Study on cost effectiveness of silk dyeing with acid dyes and basic dyes

Technology