Stripping And Topping of Sulphur Dyes from Dyed Fabric: Methods And Techniques

Stripping and topping are two important processes in the textile industry used to modify the colour of the fabric after it has been dyed. Sulphur Dyes Manufacturer in India, Stripping refers to the removal of colour from the fabric while topping involves adding a new colour to the fabric. In the case of sulphur dyes, stripping and topping are often necessary to achieve the desired colour and shade.

Stripping Processes for Sulphur Dyes:

The stripping of sulphur dyes can be accomplished by using reducing agents such as sodium hydrosulfite or sodium bisulfite, which convert the insoluble dye back into a soluble form that can be removed from the fabric. The process is carried out at a high temperature and under alkaline conditions. This allows the reducing agent to break down the dye molecule and make it soluble, which can then be removed from the fabric by washing. The stripping process is usually followed by a thorough rinsing and washing of the fabric to remove any residual chemicals and dyes.

Topping Processes for Sulphur Dyes:

Topping of sulphur dyes manufacturers involves adding a new colour to the fabric, which can be achieved by applying a new dye on top of the existing one. This process is often used to modify the colour of the fabric or to add depth to the existing colour. Topping can be done by applying a new dye in a different colour, or by using a combination of dyes to create a multicoloured effect.

Before the topping process, the fabric is usually stripped to remove any residual dye that might interfere with the new colour. The fabric is then dyed using the desired colour, and the process is followed by thorough rinsing and washing to remove any excess dye.

Stripping and topping are important processes in the textile industry used to modify the colour of the fabric. Dye Manufacturers in India produced Sulphur dyes, which are commonly used for cotton and linen, can be stripped using reducing agents and topped with a new colour to achieve the desired shade. These processes require careful consideration and expertise to ensure that the fabric is not damaged during the process.

Effective Methods for Stripping Sulphur Dyes:

It is possible to correct unevenly dyed shades on cellulosic materials with sulphur dyes using various methods. One such method is to treat the material with a warm solution of Na2S in the presence of Albigen A (polyvinyl pyrolodine). This can help to even out the shade and improve the overall appearance of the fabric.

If this method does not work, then the fabric can be treated with a solution of NaOCl or bleaching powder (2-3 gm/Litre of available chlorine). This method can help to remove the excess dye and correct any unevenness in the shade.

In some cases, bleaching with KMnO4 solution may be effective. This method involves treating the dyed material with a solution of potassium permanganate, which can help to break down the dye molecules and remove the excess colour.

Alternatively, the fabric can be treated with a warm NaOCl solution in the presence of NaOH. This method can help to bleach the fabric and even out the colour.

One such method involves treating the dyed fabric in a blank bath containing 6 g per litre sodium sulphide at high temperatures.

Another method involves using a blank dye bath at 90–95°C containing 4.5–9 g per litre sodium hydrosulphite and 2–3 ml per litre sequestering agent. This method can strip about 10–20% of the colour, and further removal of colour can be achieved by adding a stripping agent such as polyvinyl pyrrolidine.

DA-BS800 is another stripping agent that can be used to remove sulphur dyes from the fabric. The stripping process typically involves treating the fabric in a bath of sodium hydroxide and sodium hydrosulfite. It is important to note that sulphur dyes and vat dyes have similar stripping methods and application rules.

It is important to note that these methods should be used with caution and under the guidance of a professional to avoid damaging the fabric. Also, the effectiveness of these methods may vary depending on the type of fabric and the specific dye used.

Topping Techniques for Sulphur Dyes:

It is possible to top Sulphur dyes with basic dyes to brighten the shades of cotton textile materials. This process involves washing the fabric thoroughly to remove any alkali and then treating it with a basic dye in a second dye bath containing acetic acid or alum. The temperature is raised to about 60°C to control the exhaustion of the basic dye.

Topping Sulphur dyes can be an effective way to obtain brighter shades and achieve the desired colour. It can also help to minimize the cost of Aniline Black and Indigo Blue, as Sulphur dyes can be used as a mordant for these dyes.

It is important to note that the choice of basic dye and the topping process should be carefully selected based on the specific fabric and dye used to achieve the desired results.

Conclusion 

The demand for eco-friendly dyes has increased significantly in recent years, leading many dye manufacturers in India to invest in research and development to create sustainable dyeing solutions. Veeraco Colorants Private Limited is one of them. They are one of the top dyes manufacturers in India having a reputation for producing high-quality products that are used in a wide range of applications, including automotive coatings and fibre masterbatch. They offer a diverse range of products, including acid dyes, reactive dyes, solvent dyes, and pigment dispersions. Their products are designed to provide excellent colour consistency, brightness, and colour fastness, even in challenging applications.

What are Dyes and Pigments? What is the Difference between dyes and pigments?

Dyes and pigments are the elements that give a material colour. Both dyes and pigments, commonly known as dyestuffs, are frequently referred to as colourants. The size of the particle is the main distinction between colours and pigments. Compared to pigments, dyes are significantly finer. In contrast to pigments, which are typically UV stable, dyes are not. Users of dyes typically purchase their goods from dealers of the items or dyes and pigments companies in India. 

Dyes, also referred to as colourants because the colouring substance is dissolved in a liquid, penetrate the substance to which they are administered. The quality of the goods you receive from the basic dye manufacturers in India is one thing they won't skimp on.

Contrarily, pigments are made up of incredibly small pieces of crushed colouring material contained in a liquid to create a paint coating that adheres to the substrate it is administered to. Since they easily penetrate the solid slab and do not fade out during the polishing stage, dyes are employed in the polished concrete process.

		Dyes	Pigments
1.	Solubility	Highly soluble in liquids	Water and the majority of solvents cannot dissolve it
2.	Number	Readily available in a large number	Significantly fewer in number
3.	Lightfastness	Lower dyes are extremely susceptible. Lights disintegrate coloured materials by rupturing molecular electrical bonds.	Historically, it has been discovered that pigments are lightfast than dyes.
4.	Product resistance	Low in comparison to pigments	High
5.	Size	Comparing dye molecules, for instance, a head of a pin would be like connecting a football (pigment) to a dye molecule (dye)	The size of pigment particles ranges from 1-2 microns. It implies that a magnifying lens can be used to observe the particles.
6	Bonding	Electrostatic charges on dye molecules act as a means of adhering the dye to the concrete.	A binder is needed to help glue pigment together. Due to the fact that it is an inactive chemical that is only maintained in a carrier or binder
7.	Imparting colours	With the selective absorption of the dyes, dyes can add colour	Pigments either scatter light or selectively absorb it to produce colour
8.	Combustible Properties	Combustible	Non-combustible
9.	Chemical Composition	Organic compounds	Mostly inorganic substances, frequently including highly hazardous metals
10.	Longevity	Not as durable as pigments	Long-lasting compared to dyes

Conclusion

Pigments are used in a variety of textile dyeing and printing processes. Thus, it needs to have some high criteria. Veeraco is well known for its quality and high-performance pigments, which may be used in many challenging applications, such as automotive coatings and masterbatch applications for fibre. Consumers often purchase products made with pigments from retailers or Indian makers of pigment. Veeraco Colorants Private Limited was established in 1952. Many dyes and pigments are produced, offered, and exported by them. As the years passed and their labour began to bear fruit, they rose to the position of becoming one of India's leading top dyes manufacturers in India.

Read more: Pigments for Plastic

Acrylic Fabric: Characteristics, Production, & Process

 

Fabric made by acrylic dyes manufacturers in India is often referred to as polyacrylonitrile, acrylic, or acrylonitrile. Synthetic polyacrylonitrile polymer is the fabric's main component. Variations in the fabrics thread count range from 18 to 100. Despite having a low fabric breathability, it is very moisture-wicking. It is quite good at retaining heat. 

Acrylic fabrics have a very high stretch ability. The likelihood of piling or bubbling is very high. The USA is the nation where the fabric was first made. Presently, China is the largest exporting and producing nation. Warm washing temperatures are advised. They are frequently used in garments including sweaters, hoodies, boots, boot linings, hats, gloves, sporting gear, carpeting, blankets, roller brushes, upholstery, area rugs, protective gear, wigs, and hair extensions.

 

What Is Acrylic Fabric Made of?

Fabrics with acrylic fibres are created using the synthetic material acrylonitrile. Acrylic fabric is made from a form of fibre that is derived from fossil fuels since it is created by reacting specific chemicals with a variety of monomers that have a petroleum or coal base.

Since the acrylic fabric is one of the least breathable textile types available, it is preferred for applications requiring heat retention. Acrylic Dyes Manufacturers, For instance, tracksuits, hoodies, and athletic pants are frequently constructed of acrylic fabric, which is frequently used in athletic equipment. However, there are worries that acrylic could be cancer-causing, so it might be best to avoid coming into touch with this fibre.

Authentic acrylic fibre must contain at least 85% acrylonitrile; it may also contain minor percentages of other synthetic substances. The properties of the finished cloth will differ depending on the substances that are combined with acrylonitrile.

The Evolution of Acrylic Fabrics

The American DuPont Corporation invented acrylic fibre first, as it did with many other synthetic textile fibres. When acrylic fibre was created in the 1940s, the world saw this innovation as simply the next step in DuPont's quick rise to a dominant position in the global textile markets. This company had already gained notoriety throughout the world for the development of nylon and the mainstreaming of polyester production.

The advantages of acrylic became increasingly clear over around ten years, and this fabric steadily increased its market share. Consumers and business leaders at the time believed that synthetic fibres will soon completely replace natural fabrics. Consumers started to worry about acrylic's flammability over time, though, especially since wool, which acrylic was meant to replace, has one of the best flammability profiles of any fabric. However, DuPont is no longer the main supplier of acrylic fibre. The market for acrylic fibre is now led by businesses in China, India, Indonesia, and other ASEAN nations rather than this American firm. Similar to how emerging markets in developing countries want considerably less acrylic fabric, so does the American consumer market.

 Washing 

Remember that clothing made of acrylic fabric can be damaged by both hot and cold water. As a result, you should always use warm water to wash acrylic apparel. When washed in water that is too hot, acrylic can melt and harm your washing machine or other items in the load. When washed in the cold, acrylic can start to become stiff and rigid.

Additionally, more than any other fabric, the acrylic fabric is more likely to pill. A piece of clothing covered in pills the same colour as the clothes you cleaned it with will result from washing an acrylic item with clothes that don't nearly match its hue.

Customers who purchase dyes can purchase them from retailers who sell them or from renowned top dye manufacturers in India. 

How Is Acrylic Fabric Made?

There are seven phases involved in the creation of acrylic fabrics.

Step 1:

Polymerization 

The chemical process known as free radical polymerization uses a water-based solution to produce the acrylonitrile polymer polyacrylonitrile.

Step 2:

Dissolving 

Using a powerful chemical solvent, this polymer is broken down.

Step3:

Extruding

After that, the substance, which resembles gel, is prepared to be spun into acrylic fabric by an extruder. 

Step 4:

Wet or dry spinning 

Wet spinning or dry spinning, which includes evaporating the solvent with a stream of hot gas, is the common method for coagulating these fibres in a solution of the same solvent. 

Step 5:

Washing and stretching 

In order to create long, thin filaments that may be spun into yarn, the resulting fibres are then cleaned, stretched, and crimped.

Step 6:

Leading 

After being spun into yarn, acrylic fibres are put onto bobbins and delivered to companies that make textile products.

Step 7:

Weaving

These producers then use this acrylic yarn for clothing, carpeting, or a variety of other uses.

In order to create long, thin filaments that can be spun into yarn, the resulting fibres are next cleaned, stretched, and crimped. Stretching acrylic fibres, like other synthetic textile fibres, results in them being multiplied by many times their original length, which lowers costs and boosts production efficiency. Stretching is necessary to produce a usable end textile. Workers may also expose acrylic fibre to different colours and treatments at the manufacturing plant or the facility that produces textile products. For example, flame retardants are a definite requirement for acrylic fabrics; without these harsh treatments, the acrylic fabric would be extremely risky.

How is a fabric made of acrylic used?

●   Used for clothes, including gloves, hoodies, slacks, and many other sorts of cold-weather attire. 

●        Utilised in rugs, upholstery, and carpets for home ware products

●        For costumes and props

●        Regarding knitting supplies.

 

Top Acrylic Dyes Manufacturers in India is utilised in many of the same applications as this extremely well-liked natural fibre since it is made to resemble wool. For instance, clothing companies use acrylic fibre to create a variety of cold-weather clothing items, including hoodies, slacks, gloves, mittens, and sweaters. Additionally, carpeting, upholstery, rugs, and other historically dominated by wool home ware product categories are all commonly made from acrylic.

Although acrylic naturally resembles wool quite closely, depending on the spinning technique employed, it can also be made to resemble other fabrics, such as cotton. Manufacturers may create acrylic materials that resemble fur, which might be helpful for costumes or props.

One of the components of carbon fibre, which is highly sought-after in industrial applications, is acrylic fibre. Despite being extremely durable, acrylic fibre doesn't have many industrial uses due to its flammability, which prevents it from being used in a variety of industrial settings.

Knitting is one of the most popular uses for acrylic fibre. Despite several drawbacks, acrylic knitting has a vital role in the market for hobbyist knitters due to its inexpensive cost and inability to lose colour. 

Customers of dyes get their goods from Dyes and Pigments Manufacturers in India or from retailers who sell those products.

 

Types Of Dyes And Their Properties

 What are dyes?

A dye is used to add colour to different materials. Dye Manufacturers in India, For humans, colour has always held great fascination and appeal. Both natural and synthetic dyes are common types. They give kitchenware, textiles, leather goods, and even food products colour. For colouring various items, several dyes are available. The finely crushed substances found in paint, ink, and other goods that are called pigments are not dyes. In contrast to pigments, which are inorganic substances, dyes are organic substances. Everything these days comes in a variety of hues and textures. And the enormous array of colours makes this possible.

Various Types Of Dyes:

Basic Dyes

These colours are generated synthetically and cannot dissolve in water. They also go by the name of cationic dyes. Basic Dyes Manufacturers in India. These dyes have a good retention period and all of their shades are very brilliant. Acrylic fibres are coloured using basic dyes, which are reasonably priced. They react well with synthetic materials.

Vat Dyes

Vat dyes, commonly referred to as indigo dyes, are produced utilising a variety of plants. Vat dyes are applied by a method known as vatting rather than directly colouring the substrate. These dyes are insoluble in water and must be vetted to become soluble. The particles in vat dyes are quite tiny compared to other dyes. These come in fewer tints and colours. Experts typically utilise vat dyes because of the lengthy dyeing procedure.

Direct dyes

They are used to colour cellulose textiles like cotton since they are soluble in water. When utilising these kinds of dyes, dyeing is often carried out in an alkaline environment. But all the materials dyes using this type of dye require after-treatment and care to improve the shade of the dye. Direct Dyes have excellent fastness characteristics. The textile industry makes substantial use of these colours.

Acid Dyes

They are frequently used to colour protein fabrics including nylon, silk, and wool. These colours are very water-soluble. They are inappropriate for use with cellulosic material. Acid dyes work well to colour leather and other medicinal items since they have good dye fastness properties. They're excellent for the food business as well. They are also used to produce ink such as ink for printers, ballpoint pens, marker ink, ink pads, etc.

Synthetic Dyes

These artificial dyes are created chemically. They come in a wide variety of hues and tones. Because of their relatively low cost and simplicity of usage, they are used in many different sectors. Both the ecosystem and the human body are harmed by it. Yet, the use of these colours continues to grow. Some chemical substances are water-soluble.

Reactive Dyes

For cellulose, protein, and polyamide fibres reactive dyes work well. These dyes are simple to use because they come in a variety of formats. They have good light-fastness qualities and are soluble in water. Since all reactive dyes come in vibrant hues, they are ideal for the textile sector. These reactive dyes are affordable and suitable for use in large quantities. They block UV radiation and have an excellent electron arrangement.

Solvent Dyes

The emerging textile mills employ these contemporary colours extensively. Solvent dyes are non-corrosive, non-toxic, and non-flammable dyes. The fibres and polymers can be coloured more quickly and easily with these dyes. They are also quite wettable. These dyes have a significant downside in that bulk application is challenging due to the solvent’s frequently high cost. Solvent dyes come in a wide variety and make excellent alternatives to traditional, hazardous dyes.

Food Dyes

These are the synthetic colours that have been added to the meal to make it more appealing. These days, food colours are frequently utilised. The several forms they come in include pastes, liquid colours, gels, and coloured powders. These food colouring agents are used to restore the edible's colour after it has been exposed to light, heat, and storage. Food dyes must be used with caution because using them excessively might lead to several health issues. There are two types of food dyes: natural and artificial. Natural food colours can make meals more appealing and nutrient-dense. Before choosing the best food dye, exercise caution and undertake a thorough study.

Seed Colouring dyes

To help farmers to distinguish and identify different types of seeds, seed colouring dye is used to give colour to the seeds. Many kinds of seeds have various colours. The traditional method of protecting seeds and promoting plant growth is seed colouration. This strategy has also been used by major seed companies to brand their seeds. Seed colouring is a fantastic technique to distinguish the seeds and stop them from being harmed. These days, a variety of seed dyes are offered; try to select a safe dye as this can affect the growth of the plants and crops.

Conclusion 

The dyes mentioned above are just a few of the many different kinds of dyes available. Each of them has advantages and disadvantages. Depending on the product’s kind and intended usage, one must select the dye that is best for them. Veeraco Colourants Pvt Ltd is one of the best dye manufacturers of India with generations engaged in the business, they are one of the Top Dyes Manufacturers in India and have been fulfilling the colouring needs of the world for ages. Employing the latest techniques, learning from experiences, retaining a standard of products, and simultaneously turning into a brand everyone trusts. They are renowned for their high-performance pigments, which are employed in a variety of different applications from automotive coatings to fibre-grade masterbatch applications.

What is Dyes and Pigments? Advantages and Disadvantages

 

Dyes and pigments are both types of colorants used to add color to various materials. However, there are some key differences between the dyes and pigments.

Dyes are colorants that are soluble in a liquid solvent. When a dye is added to a material, it dissolves into the material, creating a uniform and transparent color. Dye Manufacturers in India, Dyes are commonly used to color fabrics, paper, textile, leather and other materials.

Pigments, on the other hand, are insoluble particles that are mixed with a binding agent to create a paste or powder. When applied to a material, the pigment particles are dispersed but not dissolved, creating an opaque and non-uniform color. Pigments are commonly used in paints, inks, plastics, fabrics, cosmetics and food.

Another key difference between dyes and pigments is their durability. Dyes tend to be less durable than pigments, as they can fade or bleed over time, especially if exposed to sunlight or washing. Pigments, on the other hand, are more resistant to fading and are often used in applications that require long-lasting color, such as outdoor paints.

Dyes:

1.     Dyes can be derived from natural sources, such as plants and animals, or they can be synthetic, produced through chemical processes.
2.      Dyes are typically used on materials that have a high affinity for the dye molecule, such as cotton, silk, and wool.
3.     Dyes can be categorized into different types based on their chemistry, such as acid dyes, basic dyes, and direct dyes.
4.      Dyes can also be classified based on their application method, such as immersion dyeing, printing, and spray dyeing.

Pigments:

1.     Pigments can be organic (carbon-based) or inorganic (metal-based) compounds, and they can be derived from natural sources or synthesized in a laboratory.
2.       Pigments are typically used on materials that have a low affinity for the pigment particles, such as plastics and metals.
3.     Pigments can be categorized into different types based on their chemical composition, such as titanium dioxide, iron oxide, and phthalocyanine blue.
4.    Pigments can also be classified based on their particle size, such as Nano-pigments, micro-pigments, and macro-pigments.

Top Dyes Manufacturers in India, describes both dyes and pigments have advantages and disadvantages, and the choice between the two depends on the specific application and desired outcome. For example, dyes are often preferred for coloring fabrics, as they provide a more even and vibrant color, while pigments are often preferred for painting and printing, as they offer a wider range of colors and greater durability.

Source: https://dyesandpigments.mystrikingly.com/blog/what-is-dyes-and-pigments-advantages-and-disadvantages

What is the difference between Basic Dyes and Sulphur dyes?

Basic dyes and Sulphur dyes are two types of colorants used in textile dyeing. The main differences between them are:

Chemical Structure: Basic dyes are water-soluble cationic dyes that are derived from bases such as Triphenylmethane, xanthene, or methylene blue. On the other hand, sulphur dyes are water-insoluble anionic dyes that contain sulphur -containing groups, such as thio groups.

Dyeing Mechanism: Basic dyes manufacturers in India, are primarily used for dyeing acrylic and cationic dye able polyester fibers by forming an electrostatic attraction between the positively charged dye molecule and the negatively charged fiber surface. On the other hand, sulphur dyes are used for dyeing natural fibers, such as cotton, wool, and silk, by forming a covalent bond with the fiber surface.

Color Fastness: Basic dyes have poor color fastness properties and tend to fade easily when exposed to light, water, or chemicals. On the other hand, sulphur dyes have excellent color fastness properties, particularly to light and washing, and are widely used for dyeing dark shades of cotton.

Environmental Impact: Basic dyes are considered to be more environmentally hazardous than sulphur dyes because of their toxicity and potential to contaminate water resources. sulphur dyes, on the other hand, are considered to be relatively safe and eco-friendly due to their low toxicity and biodegradability.

Application: Basic dyes are commonly used for bright, vibrant colors such as red, pink, and blue, while sulphur dyes are often used for darker shades such as black, brown, and navy.

pH Sensitivity: Basic dyes require an alkaline pH for effective dyeing, while sulphur dyes manufacturers in India, sulphur dyes require an acidic pH. This difference in pH sensitivity affects the dyeing conditions and may require different chemicals to adjust the pH levels.

Fiber Compatibility: Basic dyes are typically used on synthetic fibers such as nylon, acrylic, and polyester, while sulphur dyes are commonly used on natural fibers such as cotton, wool, and silk. However, some blends of synthetic and natural fibers can be dyed with either type of dye.

Dyeing Process: Basic dyes are typically applied in a one-bath process, where the dye is added to a bath of hot water and the fabric is immersed and agitated. sulphur dyes, on the other hand, require a two-bath process, where the fabric is first treated with a reducing agent to open up the fiber structure and create reactive sites, and then immersed in a bath of the  sulphur dye.

Cost: Basic dyes are generally less expensive than sulphur dyes, but this can vary depending on the specific dye and the quantity used.

In conclusion, basic dyes and sulphur dyes differ in their chemical structure, dyeing mechanism, color fastness, environmental impact, pH sensitivity, fiber compatibility, dyeing process, and cost. Dye Manufacturers in India, Understanding these differences can help determine the appropriate dye to use for a particular textile material, color, and desired outcome.

Read More: Basic Dyes Manufacturers in India