Introduction of Tie-Dye | How to Tie Dye on Fabric? | Procedure of TieDyeing

Tie-Dye

Tie-dye is a process of resist dyeing textiles or clothing which is made from knit or woven fabric, usually cotton; typically using bright colors. It is a modern version of traditional dyeing methods used in many cultures throughout the world. “Tie-dye” can also describe the resulting pattern or an item which features this pattern.

Why Tie?
The whole point of tie dyeing is to prevent the dye from reaching the fabric evenly. Any place that the dye can’t reach will stay white, or a lighter color, of course. The gradations of color from intense to light can be beautiful. You can accomplish this by folding the fabric, tieing it with string, using rubber bands, etc.

Another reason to tie is that it makes each garment of piece of cloth a small, neat bundle—much easier to handle if you have a lot to do. If you don’t tie, but just apply the dye directly, you need more space and can do fewer garments or pieces of fabric at a time.

Materials Needs for Tie-Dye: 

• Dyes – buy them at the craft store 
• White T-shirt or cotton material 
• Rubber bands 
• Plastic Bag  
• Plastic Tubs

How to Tie Dye?

Fold a piece of clothing in vertical pleats, and you’ll end up with horizontal stripes. Horizontal pleats result in vertical stripes (more slimming, you know). Diagonal pleats make a nice effect. Stitch a loose basting stitch in any shape you like, then pull the threads tight for another form of tie-dyeing that can have really cool results. For concentric circles, grab the cloth where you want the center to be, and pull, until you’ve more or less made a long tube of the garment, then apply rubber bands at intervals along the fabric. I also like the “scrunch” pattern, made by crumpling the fabric very evenly, so that ultimately it makes a nice flat disk when held with rubber bands. 

Tie-dyed Fabric

Tie dye procedure are given below as shortly:
1) Roll up t-shirt or cotton material in any type of design using rubber bands to hold it in place
2) Prepare dyes in buckets.
3) Dip the first rubber band section in one of your dye colors
4) Continue dying the shirt until you run out of white sections.
5) Place the tshirt in a ziplock bag and let sit for 24 hours
6) Remove rubber bands and hang dry
7) Wash with cold saltwater and check out your new GROOVY creation!!

Introduction of Direct Dyes | Classification of Direct Dye |Application of Direct Dyes | Aftertreatment of Direct Dye

Direct Dye:
Direct Dye is a class of dyestuffs that are applied directly to the substrate in a neutral or alkaline bath. They produce full shades on cotton and linen without mordanting and can also be applied to rayon, silk, and wool. Direct dyes give bright shades but exhibit poor washfastness. Various aftertreatments are used to improve the washfastness of direct dyes, and such dyes are referred to as “aftertreated direct colors.”Direct Dyes are molecules that adhere to the fabric molecules without help from other chemicals. Direct dyes are defined as anionic dyes with substantivity for cellulosic fibres, normally applied from an aqueous dyebath containing an electrolyte, either sodium chloride (NaCl) or sodium sulfate (Na2SO4)..

Direct Dyes 

The dyeing process with direct dyes is very simple, Direct dyeing is normally carried out in a neutral or slight alkaline dyebath, at or near boiling point , but a separate aftertreatment such as cationic dye fixing , to enhance wet fastness has been necessary for most direct dyeing .

Direct dyes are used on cotton, paper,leather, wool, silk and nylon. They are also used as pH indicators and as biological stains.

Chemicals Nature of Direct Dyes:

Chemically they are salts of complex sulfonic acids. 

Structure:-More than 75% of all direct dyes are unmetallised azo structures, great majority of them are disazo or polyazo types.

Ionic Nature:-Their ionic nature is anionic. 

Solubility:-They are soluble in water .

Affinity:-They have an affinity for a wide variety of fibers such as cotton ,viscose, silk jute ,linen etc.. They do not make any permanent chemical bond with the cellulosic fibers but are attached to it via very week hydrogen bonding as well as vander waals forces. Their flat shape and their length enable them to lie along-side cellulose fibers and maximize the Van-der-Waals, dipole and hydrogen bonds. 

Types of Direct Dyes:

The SDC classification of direct dyes is follows

(1) Class A – dyes that are self-levelling, i.e. dyes of good migration or leveling properties.

(2) Class B – dyes that are not self-levelling, but which can be controlled by addition of salt to give level results; they are described as salt-controllable.

(3) Class C – dyes that are not self-levelling and which are highly sensitive to salt, the exhaustion of these dyes cannot adequately be controlled by addition of salt alone and they require additional control by temperature; they are described as temperature-controllable.

Application of Direct Dyes

Direct dyes are usually applied with the addition of electrolyte at or near the boil in the machines capable of running at atmospheric pressure .But in HTHP dyeing machines it is carried out at temperatures above the boil in case of pure as well as blended yarns. 

An addition of alkali, usually sodium carbonate, may be made with acid-sensitive direct dyes and with hard water as well as to enhance the dye solubilisation. When cellulose is immersed in a solution of a direct dye it absorbs dye from the solution until equilibrium is attained, and at this stage most of the dye is taken up by the fibre. The rate of absorption and equilibrium exhaustion vary from dye to dye. The substantivity of the dye for cellulose is the proportion of the dye absorbed by the fibre compared with that remaining in the dyebath.

Dyeing Method

The color is pasted well and dissolved in boiling water to get a lump free solution .An addition of 0.5–2 g l–1 sodium carbonate may be advantageous when applying dyes of only moderate solubility in full depths.

• The dyebath is set at 40°C,
• Raise to the boil at 2 degC min–1
• Hold at the boil for 30–45 min, 
• During hold add 10–15 g l–1 of sodium chloride or calcined Glauber’s salt. Light shades are dyed without or lesser addition of salt.
• Improved yields can be achieved when applying full depths by cooling to 80°C at the end of the period at the boil, adding a further 5 g l–1 salt and rising to the boil again
• Dye bath variables which must be considered for level dyeing,

1.Temperature of Dyeing and rate of heating

2.Electrolyte concentration and addition

3.Time

4.Dye solubility

5.Use of leveling agent 

After Treatment of Direct Dyed Material

The wet fastness properties (particularly washing, water and perspiration) of virtually all dyeing of direct dyes are inadequate for many end uses but notable improvements can be brought about by after treatments.

• Diazotisation and development 
• Metal salt treatments 
• Cationic fixing agents 
• Formaldehyde treatment 
• Cross linking agents and resin treatments 

Stripping:- Most direct dyes can be stripped of the use of stripping salts (Sodium Hydrosulphite) and/or by using a chlorine bleaching agent such as sodium hypochlorite, without harmful effects on the fibres.

Color fastness properties of Direct Dyed material: Generally these dyes are used where high wash fastness is not required.

Wash Fastness: Poor unless treated with suitable dye fixing agent and/or fastness improving finishing agent.

Light Fastness:-Good

Rubbing Fastness: Moderate to Good

Chemical Wash Fastness:- Poor

Sulpher Dyes | History of Sulpher Dyes | Trade Names of Sulpher Dye

Sulpher dyes are complex heterocyclic molecules or mixtures formed by melting or boiling organic compounds containing amino or nitro groups with Na-polysulphide and Sulpher. Sulpher dyes are so called as they all contain Sulpher linkage within their molecules.

Sulpher dyes are highly coloured, water insoluble compounds and have to be converted in to water soluble substantive forms (lucoforms) before application to the textile materials. This conversion is carried out by a treatment with a reducing agent like dilute aqueous Na2S. Since this lucoform of Sulpher dye is substantive to cellulosic materials. They are absorbed on the fibre surface. Then they are reconverted original water insoluble form of dye by oxidation. This oxidation is carried out by “airing” (exposure to air) or by using an oxidizing agent like Na-dichromate (Na2Cr2O7).

The reducing agents converts the “S” in dye in to –SH group and the Sulpher linkages. Then inside the material the thiols containing –SH groups are oxidized & thus reconverted to original form of dye.

This is shown in the bellow:
Dye-S-S-Dye + 2[H] = Dye-SH + HS-Dye

Dye-SH + HS-Dye +[O] = Dye-S-S-Dye + H₂O

Sulpher gives best result (Bright Tone) when they are used to produce black, Black & brown shades but red shades cannot be obtained by Sulpher dyes.
 

History of Sulpher Dyes

The history of Sulpher dyes may be summarized as below:
1. The first Sulpher dyes where made in 1873 heating saw dust, caustic soda and Sulpher. It occurred by chance when a reaction vessel containing Na2S was leaking and the saw dust was used to wipe the solution coming out. Later a cotton fabric come in contact with this contaminated sawdust and become stained.

2. The real pioneer of Sulpher dyes was vidal who produce vidal black (Name of Sulpher dye) by fusing para-phenylene diamine with Na2S & Sulpher in 1893.

3. In 1897 Kalischer produced Immedial Black FF by heating 2, 4-dinitro-4-dihydroxy diphenylamine with Na-poly sulphide.

4. In 1896 Read Holliday introduced a range of grey, brown and black Sulpher dyes by the action of Sulpher, alkali sulphides and many organic compounds.
 

Method of manufacture of Sulpher dye

Aromatic Hydro Carbon Containing Hydroxy amino or nitro group      =        Sulpher Dye

Trade Names of Sulpher dye

 

Trade Names	Name of Manufacturer	Country of origin
Calcogen	Dyes Dept. American Cyanamid Co.	USA
Pyrogene	Ciba	Switzerland
Thional	Sandoz	Switzerland
Solfo	ACNA	Italy
Sulfogene	Du pont	USA
Thional	Imperial	UK
Mitsui Sulpher	Mitsui Chemicals Ind. Co. Ltd	Japan