1 What is warp-knit fabric?

Warp-knit fabric is a type of textile created by interlocking loops of yarns along the lengthwise or warp direction of the fabric. In warp-knitted fabrics, each loop is made from a separate strand of yarn that is fed into the knitting machine from a warp beam. Unlike weft-knit fabrics, which are made by interlocking loops of yarn in the widthwise or weft direction, warp-knit fabrics are generally more stable and less stretchy.

Warp-knit fabrics can be made from a variety of fibers, including synthetic materials like polyester and nylon, as well as natural fibers like cotton and wool. They are used in a wide range of applications, especially sportswear, swimwear, outerwear, lingerie, upholstery, and industrial textiles. Warp-knit fabrics is ideal for garments that require high flexibility and movement.

2 What is interlock fabric?

Interlock fabric is also known as double knit fabric that is created by interlocking two sets of knit stitches in a vertical manner. It is a variation of rib knit fabric, but instead of having vertical ridges on both sides of the fabric, interlock fabric has a smooth surface on both sides. Interlock fabric is created using a knitting machine that has two sets of needles set up in a way that allows them to interlock with one another to form a double-sided fabric. Therefore, the nature of this construction allows it to have a built-in stretch and to drape really well on the body. Interlock fabric is also commonly used as a lining material in jackets, coats, and other outerwear, as it provides warmth and a soft feel with the skin.

Easy to sew it holds its shape well, making it ideal for fitted garments.

3 What is circular knitting fabric?

Circular knit fabric is a type of knitted fabric that is produced on a circular knitting machine. It is created by knitting yarn in a continuous tube, with the fabric growing outward in a circular direction. The resulting fabric has a seamless construction, which means that there are no seams running down the length of the fabric.
As warp-knit and interlock, also circular knit fabric is two-way stretch, with application suitable for high-end and also form-fitting lingerie, according to its weight and surface.

4 Polyamide fabric, Polyester fabric, what is the difference?

Polyamide Fabric:

Polyamide is a synthetic material derived from petroleum, which first became available around World War II and was used for military products and as a silk replacement for items like stockings. Now, we’re more likely to find it in activewear, swimwear and other technical performance garments because of its durability and useful stretch properties. Polyamide fabric is commonly known as Nylon and it is made by a compound of chemical components, resulting in a long-chain chemical structure which is then extruded, spun into filaments and warped onto beams, to be suitable for different knitting processes. Nylon fabric is lightweight, durable and abrasion-resistant, making it a popular choice for a variety of applications such as clothing, outdoor gear, luggage, and industrial materials. Polyamide yarn can be weaved and knitted into a variety of fabrics: from smooth, to textured and it is suitable to be dyed in a wide range of bright colors. The hand feeling of Polyamide fabric is overall comfortable and silky-smooth, depending on the fabric and application it is designed for.

Polyester fabric:

Polyester fabric also originated from a chemical reaction of elements of fossil origins – Petroleum to be specific – resulting in a long-chain chemical structured polymer, that is extruded into filaments and then spun onto coils to be applied to different knitting processes. Polyester fabric is known for its durability, resistance to high temperatures, wicking properties, wrinkle resistance, chlorine resistance performances and the ability to retain its shape, even after repeated washings. It is also quick-drying, making it ideal for outdoor and sportswear; it can also be used for performance swimwear. The hand feeling of Polyester fabric is overall comfortable, cotton-like and soft, according to the type of yarn and the applications it is designed for. 

What is the difference between Polyamide and Polyester fabric?
  • Chemical composition: Polyamide 6 is obtained by the polymerization of caprolactam. Polyester is originated from a chemical reaction in which ethylene is the original raw material;
  • Melting point of Polyamide is around 220 ℃, while Polyester resists to higher temperature, till 260 ℃;
  • Melting point of Polyamide is around 220 ℃, while Polyester resists to higher temperature, till 260 ℃;
  • Polyamide preferred dyeing process implies the use of acid dyestuff, while for Polyester reactive dyestuff under pressure with high temperature;
  • Applications: Polyester is used mostly for clothing, specifically t-shirts and sportswear. It is versatile and can be used to make both cold and warm weather clothing. Polyamide is used for sportswear and outerwear, such as jackets, but given its embedded elastic properties it is used to make legwear, swimwear, and underwear garments;
  • Durability: Both fabrics are durable and resistant to abrasion, tearing, punctures, UV radiation and color fading.
  • Comfort: Polyamide fabric tends to feel smoother and softer to the touch, while polyester fabric can feel slightly stiffer with good compressive power properties;
  • Breathability and Wicking: Polyamide is generally considered to be more breathable than Polyester, and a more indicated choice for swimwear because it dries faster. Polyester is more likely used in sportswear, for its thermic-adaptive and compressive properties. It is important to note that the breathability as much as the wicking properties of both fabrics, can vary depending on a range of factors, such as fabric weight, knitting construction, and finishing treatments. For example, a lightweight Polyester fabric with a loose construction, may be more breathable than a heavyweight Polyamide fabric with a tight construction;
  • Colorfastness: Polyamide is more sensitive to light, chlorine and perspiration fading, while Polyester to washing, temperature, crocking, water and seawater fading.
  • Stretching properties: Polyester is overall considered more rigid than Polyamide with a lower capacity to absorb water. Its extension capacity is around +30% of its original length, while Polyamide 6.0 is around +30-45%.
Check out for more Hung Yen Polyamide and Polyester fabrics here.

5 Post-consumer and Post-industrial Recycled Polyamide,
what is the difference?

Post-consumer Recycled Polyamide and post-industrial Recycled Polyamide are two different types of recycled yarn that are commonly used in textile applications. Both options have benefits for textile applications, first of all their contribution at reducing textile waste, by repurposing discarded materials, that would otherwise end up in landfills and in the Oceans, reducing also the impact of the direct upstream emissions in the supply chain (SCOPE 1) compared to the production of new virgin yarns.
Performance characteristics, and costs may vary depending on the specific factor, such as origin of the regenerated raw material and availability.
Post-consumer recycled Polyamide:
Post-consumer Recycled Polyamide, also known as post-consumer Nylon, is made from wastage regenerated materials, such as discarded fishing nets, carpets, and mono-components clothing. The waste material is collected, sorted, cleansed and processed chemically to become new fibers and yarns for new raw material porpoise. 
Post-industrial recycled Polyamide:
Post-industrial Recycled Polyamide, also known as pre-consumer Nylon, is made from waste materials generated by the yarn and textile manufacturing process. These materials can include items like leftover textile Nylon scraps, trimmings, and offcuts. The waste is collected, sorted, and chemically processed to become new fiber and yarn. 

6 What are Bisphenols (BPs) in textile?

Bisphenols (BPs) are synthetic compounds that contain two phenol groups connected by a bridge, which used to make synthetic fibers for clothing and other textiles in fashion industry. Using BPs in textiles can provide properties mostly linked to increased flexibility, durability

However, there are some concerns about human health and environmental impacts of BPs, particularly Bisphenol A (one of the most well-known Bisphenol). Studies shows that BPA can act as an endocrine disruptor, which means that it can interfere with the body’s hormonal system. There are also concerns about the potential for BPs to accumulate in the environment and in living organisms due to the pollution of discarded materials on landfills.

Understanding these concerns Hung Yen Knitting & Dyeing complies with the most authoritative international certification for product safety in Textile, Oekotex Standard 100 – Class I, ensuring our fabrics to be suitable to the most sensitive applications such as garments for babies.

7 What are PFC compounds in textile?

PFC compounds, also known as perfluorocarbons, are a group of chemicals that are sometimes used in textiles to provide water and stain resistance. The term “PFC” refers to their chemical structure and to the length of the carbon chain in the molecules. The higher the number of carbon molecules the lower is the capacity to break down in the environment.

Perfluorocarbons are a type of fluorinated chemical, which means that they contain fluorine atoms. They are used in textile applications because of their high oil and water repellency properties. Therefore, their presence can be found in surface coatings and waterproof and insulating. However, the use of PFC in clothing has adverse effects and controversial feelings on human health and environment potential damages, raising attention recently about their progressive limited usage if not ban for different industrial applications including textile.
Hung Yen Knitting and Dyeing DWR Durable Water Repellent treatment is guaranteed 100% PFC free. 

8 Color fastness to Chlorine and Chlorine resistance,
what is the difference?

Do you think color fastness to chlorine and chlorine resistance are related concepts? Actually they are not exactly the same thing.
Color fastness to chlorine refers to the ability of the fabric to maintain its color when exposed to chlorine solution for a certain amount of prolonged time. Chlorine is a common chemical used in swimming pools to sanitize water in lower concentration, however the extended use of a garment, such as swimsuits exposed to this application can see its properties fading away. In fact, if the properties of the yarns doesn’t guarantee high quality to chlorine resistance, the result can be disappointing from the very first usage of the garment and the consumer can experience colors, or elastic properties fading away for the swimwear.
Chlorine resistance refers to the ability to resist to possible damages and degradation of the fabric – especially Elastomeric blended yarns – when exposed to chlorine solution, from low to high concentrations. Textiles and garments – especially made for swimwear – that are not made and tested to guarantee high chlorine-resistance (Creora®) or chlorine-proof performances (XLANCE) can be defective to this specific requirement, or damaged when exposed to chlorine solution, which directly alters their durability and lifespan.

A good maintenance of the garment especially while designed for performance swimwear application is equally essential and recommended. In fact, despite the high quality of the yarn, the degradation can also happen when the garment is not properly rinsed or washed and dried after being exposed to short or long time chlorine solution soaking. We always remind the importance of the proper and attentive maintenance of the garment as label indicates, in order to maintain and increase their durability in time.

9 What are the standard methods to test swimwear fabric?

Swimwear and sportswear fabric uses a variety of international standards methods, such as AATCC, ISO and ASTM, and customized derivations of these according to buyer specific testing requirements. These tests help to conventionally define the quality and durability standards of a certain kind of  fabric and garments. Some examples of testing methods include:

Chlorine resistance test: This test involves exposing the fabric to a high concentration of chlorine to expand the standard conditions of a chlorinated swimming pool soaking and usage. The fabric is then evaluated for any changes in color but especially the loss of elastic power;

UV Protection test: The fabric is exposed to ultraviolet light ray stream to assess its ability to deflect different wave of UV rays. The property is directly linked to the concentration of TiO2 of the Polymer, which also defines its opacity;

Stretch and Recovery: this test measures in data the physical property of a fabric, to stretch and recover back to its original shape after being mechanically pulled by a dynamometer. The gap between the initial recorded elastic data and the final, during the test stages of the fabric loop, determines the hysteresis of its elastic properties. The wider is the gap between the curves, the less power is retained to recover by the fabric, after long exposure to extended stretch and recovery action;

Abrasion resistance: This test evaluates the fabric’s ability to resist and not tear apart after long exposure to rubbing or friction actions. It helps to determine the fabric’s longevity and durability under specific and prolonged actions and forces mostly applied to sportswear garment;

Water absorption and wicking: This test measures how much water the fabric can absorb, in how much time. It defines the ability of the fabric to absorb and convey moisture;
Pilling test: this test measures the fabric’s resistance to pilling abrasion, which can determine the formation of small balls of fiber – pulled out from the abrasive action – on the surface of the fabric. It helps to determine the fabric’s durability and overall quality;

Opacity test: property of the fabric to not be able to see through when it is pulled, manually or mechanically, in both wet and dry conditions. It simulates the visual stretching performances under specific load and on critical fitting points on the body, such as glutes, tights, elbows and knees. Beside the dimension of the yarns and the weight of the fabric, this property is also link to the construction and elastic properties of the fabric.

Tearing strength: the tear strength is required in high performance applications as well as in the conventional textiles, that is, in the industrial applications, bullet proof jackets, tents, worker jeans, sacks, aesthetic apparel and many more applications. This is also important in the industrial textiles where heavy duty work is performed. High tear strength of textiles makes sure that the punctures in the fabrics do not propagate easily.

10 What is Elastolefine?

Elastolefin or XLA, best known today as XLANCE is an elastic monofilament yarn with unique chlorine proof, high temperature and chemical resistant properties, thanks to its chemical composition. This elastic yarn is used in the production of swimwear, sportswear and functional wear applications.

In high performance swimwear, Elastolefin is often used in combination with other materials, such as Nylon and Polyester, to create stretchy and form-fitting garments resistant to chlorine erosion. The combination of these materials provides excellent shape retention and resistance, ensuring the long lifespan of the swimwear garment.
See more our XLANCE collection here.

11 What is Recycled Spandex?

Recycled Spandex is another important step forward in textile innovation, to reduce the environmental impact of the industry, promoting a more circular and sustainable practice in the textile supply chain.
Mostly made from post-industrial textile waste, as much as for other regenerated synthetic yarns, also Recycled Spandex retains the same properties of its Virgin equivalent version with the unquestioned benefit to cut those emissions, otherwise inevitable with the production of standard Virgin Spandex yarn. It retains all the properties of the equivalent virgin version and the capability to increase the original length from 4 to 7 times.

12 Bio based Polyamide and Polyester for textile application?

The textiles industry is constantly challenged to create more and more sustainable solutions, especially when it comes to man-made synthetic fibers and yarns. Bio-based materials are considered the next accessible and promising alternative to achieve circularity in textile consumer goods. 
Their plant and cellulosic based origin represents the most valid regenerative source of material that can replace the more polluting virgin and recycled equivalent synthetic yarns from fossil origins.

13 What is PBT?

PBT stands for polybutylene terephthalate, which is a thermoplastic polymer used in a variety of applications. Known for its high strength and resistance to heat and chemicals, it is a good choice while blended with other yarns for applications that require durability for training and performance swimwear and sportswear.

14 What is The Higg Index?

The Higg Index is a suite of tools developed by the Sustainable Apparel Coalition (SAC) to measure and evaluate the environmental and social sustainability performance of products and companies in the textile, apparel, and footwear industries. The SAC is a global membership organization that brings together stakeholders from across the industry aimed to work towards a more sustainable future.

It provides companies with a standardized framework for measuring and comparing their sustainability performance, as well as a roadmap for improvement. It also helps to identify opportunities for cost savings and increased efficiency by reducing waste and improving resource use.

It is also recognized by various industry initiatives, such as the ZDHC Roadmap to Zero, and is increasingly being used by governments and other stakeholders as a benchmark for sustainability in the industry.

Hung Yen Knitting and Dyeing has been a member of The Higg Index since 2017.

15 What is ZDHC – Roadmap to Zero?

Zero Discharge of Hazardous Chemicals (ZDHC) Roadmap to Zero is a collaborative initiative among major retailers, brand and manufacturers in the textile, footwear, apparel industries to monitor and gradually eliminate the use of potentially hazardous chemicals in their supply chains. The main goal of the ZDHC Roadmap to Zero is to develop and implement safer chemical warehouse management practices across the entire supply chain, from raw material production to finished product manufacturing. This involves a comprehensive approach to chemical management that includes the development of safer chemical alternatives, the adoption of best practices for chemical use and handling, and the establishment of effective chemical management systems.

The ZDHC Roadmap to Zero initiative provides a framework and tools to help companies implement safer chemical warehouse management. This includes the ZDHC Gateway, an online platform that provides information on safer chemical alternatives and best practices, and the ZDHC Chemical Module, a tool for assessing and managing chemical risks in the supply chain.

Hung Yen Knitting and Dyeing has been a member of the ZDHC program since 2017.

16 What are Color Index Systems?

The Color Indexes are standardized color reproduction systems used in various industries: printing, graphic design, product design, fashion. Based on trends forecasting according to the application and year, the systems assign a unique identification number to each color, allowing manufacturers, printers and designers to accurately specify and control colors for printing projects across different mediums and materials. Two representative color coding technologies also for textile applications – even if they apply two different methods – are Pantone Color Index and Coloro, from WGSN.

Utilizing extensive tools to analyze costumes changes and final consumer needs, researching trends from the best international fashion runways we recreate an exclusive palette of new colors that anticipates the trends for swimwear and sportswear applications. 

See our Color Card Preview here.

17 How we set the trends for our color collections?

Utilizing extensive tools to analyze costumes changes and final consumer needs, researching trends from the best international fashion runways we recreate an exclusive palette of new colors that anticipates the trends for swimwear and sportswear applications. 

See our Color Card Preview here.

18 Vietnam FTAs and Cepa agreements

ASEAN Free Trade Area (AFTA): Vietnam is a member of the Association of Southeast Asian Nations (ASEAN), which has established a free trade area among its members, including Vietnam.

Vietnam-Japan Economic Partnership Agreement (VJEPA): Signed in 2008, this agreement aims to promote economic cooperation between Vietnam and Japan, reduce trade barriers, and increase investment.

Vietnam-Korea Free Trade Agreement (VKFTA): This agreement was signed in 2015 and aims to eliminate tariffs on most goods traded between Vietnam and South Korea, improve market access for services, and increase investment.

Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP): Vietnam is a member of this multilateral FTA, which was signed in 2018. It aims to reduce tariffs and non-tariff barriers to trade among its members, including Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, and Vietnam.

EU-Vietnam Free Trade Agreement (EVFTA): This agreement was signed in 2019 and aims to eliminate tariffs on most goods traded between Vietnam and the European Union, improve market access for services, and increase investment.

July 2023 Vietnam and Israel signed a free trade agreement, predicting it would quickly boost annual bilateral trade by nearly 50 percent.

Vietnam has also signed several other FTAs with countries such as China, Chile, and Russia, among others. These FTAs have helped to promote economic growth and investment in Vietnam and have increased its competitiveness in the global marketplace. In 2023 the country is in negotiations for three more FTAs – Vietnam – UAE, Vietnam – EFTA (with Switzerland, Norway, Ireland and Liechtenstein), and the ASEAN-Canada FTA.

19 What is Recycled Polyester?

Recycled Polyester, also known as rPET (recycled polyethylene terephthalate), is another type of engineered fabric made from recycled PET plastic bottles or other Polyester based waste. 

As for other recycled materials repurposed for textile applications, Recycled Polyester offers several environmental benefits: prevents plastic waste to end up in landfills or Oceans, it helps to reduce the consumption and processing of new virgin raw materials, saving energy, reducing greenhouse gas emissions and water usage. The properties of Recycled Polyester fabrics are equal in terms of quality and functionality to virgin yarn.