Specification Parameters and Testing Standards of Fabrics

 When we get a fabric or buy a piece of clothing, in addition to the color, we will also feel the texture feel of the fabric with our hands and even to understand the basic parameters of the fabric: width, grammage, density, raw material specifications, etc. Without these basic parameters, there is no way to communicate. Today, I will take you to understand the specifications of the fabric and common test methods.

Specification parameters of woven fabrics

The structure of woven fabrics is mainly related to warp yarn fineness and weft yarn fineness, warp density and weft density, fabric organization, and the main specification parameters are length, width, thickness, weight, etc.

Width

The width refers to the lateral width of the fabric, the unit is generally cm, international trade is sometimes expressed in inch. The width of the woven fabric is affected by the width of the loom during the fabric processing, the degree of shrinkage, the end use, the shaping stenter, and other factors. The width can be measured directly with a steel ruler.

Length

The length of a section of fabric, commonly used unit is m or yard. The length is mainly based on the type and use of fabric, but also considers the unit weight of the fabric, thickness, volume capacity, handling, as well as printing and dyeing after finishing and row material cutting and other factors. The length is usually measured on a fabric inspection machine.

Generally speaking, the length of cotton fabric is 30~60m, the length of fine imitation wool fabric is 50~70m, the length of coarse wool fabric is 30~40m, the length of plush and camel is 25~35m, and the length of silk fabric is 20~50m.

Thickness

Under certain pressure, the distance between the front and back of the fabric is called thickness, the commonly used unit is mm. The thickness is usually measured with a fabric thickness tester. The thickness of the fabric is mainly determined by the yarn fineness, fabric organization and the degree of flexion of the yarn in the fabric. The thickness of the fabric is used less in the actual production, usually with the gram weight of the fabric to indirectly express.

Gram weight

The gram weight of the fabric, that is, the weight of the fabric unit area, commonly used unit is g/m2 or oz/yard2. The gram weight of the fabric is related to factors such as yarn fineness, fabric thickness and fabric density, which have an important impact on fabric performance and are the main basis for fabric prices. In commercial transactions and quality control, gram weight is increasingly becoming an important specification and quality indicator.

In general, 195g/m2 or less is a light fabric, suitable for summer clothing, 195 ~ 315g/m2 belongs to the thick fabric, suitable for spring and autumn clothing, 315g/m2 or more is a heavy fabric, suitable for winter clothing.

fabric	cotton woven	fine wool-like fabric	woollen fabric	silk fabric
gram weight	70~250g/m2	130~350g/m2	300~600g/m2	20~100g/m2

Warp density and weft density

The density of fabric refers to the number of warp or weft threads per unit length, referred to as warp density and weft density, generally expressed as number/10cm or number/inch. For example, 200/10cm*180/10cm, said the warp density of 200/10cm, weft density of 180/10cm. In addition, silk fabrics are often expressed as the sum of the number of threads per square inch range, often expressed in T, such as 210T nylon spinning.

Within a certain range, the strength of the fabric increases with the increase in density, but the density is too large strength is reduced. The fabric density is proportional to the weight, the smaller the fabric density, the softer the fabric, the lower the elasticity of the fabric, drapability, and warmth.

The representation of the woven fabric

In production, fabric specifications need to indicate the fabric fineness of warp yarn and weft yarn, warp density and weft density at the same time, such as the specifications of wool and polyester polisher expressed as: 16.7tex*2*25tex, 272/10cm*222/10cm.

Specification parameters of Knitted fabric

The basic structural unit of knitted fabric is the loop, and the knitted fabric is made by connecting the loops in series with each other. Therefore, knitted fabric has the characteristics of soft texture, elasticity and easy deformation.

Knitting machine gauge

Machine gauge is a knitting machine term, but it has a strong relationship with yarn fineness and is often used to indicate knitted fabrics. Machine gauge indicates the sparseness of needle arrangement on a knitting machine and refers to the number of needles in 25.4mm (1inch), denoted by G. For example, 28G means 28 needles in 1inch, i.e. 28 needles. For example, 28G means that there are 28 needles in 1inch. In general, different machine gauges are suitable for different finenesses of yarn.

Loop length

Loop length is an important physical parameter of knitted fabrics, which refers to the yarn length of each loop, generally in mm as a unit. The longer the loop length of knitted fabric, the smaller the number of loops per unit area, the looser the fabric, easy to disperse, when subjected to external forces, the easier to deformation, its resistance to pilling, anti-hooking and fastness the worse.

In warp-knitted fabrics, the loop structure is shown in the figure above. A complete loop consists of a loop stem (green part) and an extension (red part).

Density

Density refers to the number of loops per unit length (usually 50 mm). The density of course direction of a knitted fabric is related to the machine gauge of the knitting machine used, so most of the time, after knowing the machine gauge, there is no need to specify the density of course direction. The density of the knitted fabric reflects the degree of the sparseness of the fabric, the smaller the density, the more sparse and permeable the fabric.

Gram weight

Gram weight indicates the weight of the knitted fabric per unit area, usually expressed as g/m2 or oz/yard2. As the elasticity of knitted fabric hit, good extension, with the length is not easy to measure accurately, therefore, in commercial trade, gram weight is often used as the basis for valuation.

Width

It is the width of the knitted fabric, usually expressed in cm or inch. The width has a gross width and effective width, the gross width refers to all the width of the fabric, the effective width refers to the effective width of the fabric that can be used.

The representation of the knitted fabric

The representation method of knitted fabric, in addition to the fabric specification, generally also include the machine gauge, total number of needles, yarn specification composition, finished product specification, etc.

For example, 15G*34inch*1860T 29.15tex cotton*240g/m2*65inch

It means the machine gauge is 15G, the total number of needles is 1860T, the raw material is 29.15tex cotton yarn, the gram weight is 240g/m2, the width is 65inch knitted fabric.

Test standard

Fabric density

The density of fabrics includes the warp density and weft density of woven fabrics and the density of knitted fabrics. At present, the following test standards are commonly used.

ISO 7211-2	Textile – Woven fabrics – Construction – Methods of analysis – Part 2: Determination of number of threads per unit lenght
ASTM D3775	Standard Test Method for Wrap (End) and Filling (Pick) Count of Woven Fabrics
ASTM D3887	Standard Specification for Tolerances for Knitted Fabrics
GB/T 4668	Textile – Woven fabrics – Determination of number of threads per unit length

Fabric gram weight

ISO 3801	Textile – Woven fabrics – Determination of mass per unit length and mass per unit area
ASTM D3776/D3776M	Standard Test Methods for Mass Per Unit Area (Weight) of fabric
GB/T 4669	Textiles – Woven fabrics – Determination of mass per unit length and mass per unit area

Fabric width

ISO 22198	Textiles – Fabrics – Determination of width and length
ASTM D3774	Standard Test Method for Width of Textile Fabric
GB/T 4666	Textiles – Fabrics – Determination of width and length

Fabric thickness

ISO 5084	Textiles – Determination of thickness of textiles and textile products
ASTM D1777	Standard Test Method for Thickness of Textile Materials
GB/T 3820	Textiles – Determination of thickness of textiles and textile products