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Learn the three major identification methods for textile fabrics and become an expert!

TIME:2023/11/18 14:15:00

The identification of textile fabrics can mainly be carried out from three directions: the composition of textile fabrics, the front and back, warp and weft directions, and the appearance quality of textile fabrics. By identifying these three directions, fabric buyers can help find high-quality and affordable fabrics.

Identification of the Composition of Textile Fabrics

01 Sensory identification method

(1) Main methods

Eye observation: Use the visual effect of the eyes to observe the brightness, dyeing condition, surface roughness, and appearance characteristics of tissues, patterns, and fibers of the fabric;

Hand touch: Use the tactile effect of the hand to feel the softness, hardness, smoothness, roughness, details, elasticity, warmth, etc. of the fabric. The strength and elasticity of fibers and yarns in the fabric can also be detected by hand;

Ear listening and nose smelling: Hearing and smell are helpful in determining the raw materials of certain fabrics. Silk has a unique silky sound; The tearing sound of different types of fiber fabrics varies; There are differences in the odor between acrylic and wool fiber fabrics.

(2) Four steps

The first step is to preliminarily distinguish the major categories of fibers or fabrics;

The second step is to further determine the type of raw material based on the sensory characteristics of the fibers in the fabric;

The third step is to make a final judgment based on the sensory characteristics of the fabric;

Step 4, verify the judgment results. If there is little confidence in the judgment, other methods can be used to verify it. If the judgment is incorrect, sensory identification can be performed again or combined with other methods for identification.

02 Combustion identification method

The combustion characteristics of common textile fibers:

① Cotton fibers burn quickly when exposed to fire, producing a yellow flame with an odor; Slightly gray white smoke, which can continue to burn after leaving the fire. After blowing out the flame, there are still sparks that continue to burn, but the duration is not long; After combustion, it can maintain the original velvet shape, and is easily broken into loose ash by hand. The ash appears as a fine and soft gray powder, and the burnt part of the fibers is black;

② Hemp fibers burn quickly, soften, do not melt, do not shrink, produce yellow or blue flames, and have a smell of burning grass; Leave the flame and continue to burn rapidly; Fewer ashes, appearing in the form of light gray or white grass dust;

③ Wool, when exposed to flames, does not immediately burn, first curls, then smokes, and then the fibers bubble and burn; The flame is orange yellow in color, with a slower burning speed than cotton fibers. It immediately stops burning after leaving the flame and is not easy to continue burning, with a foul smell of burning hair and feathers; Ash cannot maintain its fiber state, but is an amorphous or spherical shiny black brown brittle block that can be crushed with just one press of a finger. The amount of ash is large and has a burning odor;

④ Silk, which burns relatively slowly, melts and curls, shrinks into a ball when burned, and has a foul smell of burning hair; Leaving the flame with a slight flash, slowly burning, and sometimes self extinguishing; Grey is a crisp black brown ball that can be crushed with just one press of your fingers;

⑤ Viscose fibers have similar combustion characteristics to cotton, but their combustion speed is slightly faster, with less ash and sometimes difficult to maintain their original shape. Viscose fibers emit a slight hissing sound when burned;

⑥ Acetate fiber has a fast burning speed and sparks. It melts while burning, with a pungent vinegar taste when burned; When leaving the flame, melt while burning; Grey is an irregular block with black luster that can be crushed with fingers;

⑦ Copper ammonia fiber has a fast burning speed, does not melt or shrink, and has a smell of burning paper; Leave the flame and continue to burn rapidly; Less ash, appearing light gray or gray white;

⑧ Nylon, when close to the flame, causes fiber shrinkage. When in contact with the flame, the fiber quickly shrinks and melts into a transparent gel, with small bubbles at the same time;

⑨ Acrylic fiber, melting and burning at the same time, with fast burning speed; The flame is white, bright and powerful, sometimes with slight black smoke; Having a fishy or pungent odor similar to burning coal tar; Leave the flame and continue to burn, but the burning speed is slow; The ash is a black brown irregular brittle ball that is easily crushed with fingers;

⑩ Vinylon, when burned, the fibers contract rapidly and burn slowly, with a small and almost smokeless flame; When a large amount of fibers melt, a large dark yellow flame and small bubbles will be generated; When burned, there is a special odor of calcium carbide gas; Leaving the flame and continuing to burn, sometimes self extinguishing; The ashes are small black brown irregular brittle beads that can be crushed with fingers;

⑪ Polypropylene fiber, shrinking while melting, slowly burning; There is a bright blue flame, emitting thick black smoke, and colloidal droplets; Has a smell similar to burning paraffin; Leaving the flame and continuing to burn, sometimes self extinguishing; The ash is in an irregular hard block shape, transparent, and not easily crushed with fingers;

⑫ Chloroprene, difficult to burn; Melting and burning in flames, emitting thick black smoke; Immediately extinguish the flame after leaving and cannot continue to ignite; There is an unpleasant and pungent chlorine odor when burning; The ashes are irregular black brown hard lumps that are not easily crushed with fingers;

⑬ Spandex, which expands into a circular shape near the flame and then contracts and melts; Melting combustion in flames, with a relatively slow combustion rate and a yellow or blue flame color; Leaving the flame and melting while burning, slowly self extinguishing; There is a special pungent odor when burning; The ash is a white adhesive block.

03 Density gradient method

The identification process of density gradient method is as follows: first, a density gradient solution is prepared. The preparation method is to appropriately mix two light and heavy liquids with different densities that can be mixed with each other. Generally, xylene is used as the light liquid, and carbon tetrachloride is used as the heavy liquid. By utilizing diffusion, light and heavy liquid molecules diffuse at the interface of the two liquids, forming a density gradient solution with continuous changes from top to bottom in the density gradient tube. Use standard density balls to calibrate the density values at various heights.

Then, the textile fibers to be tested are subjected to pre-treatment such as degreasing and drying to form small balls. The small balls are sequentially placed in a density gradient tube, and the density value of the fibers is measured and compared with the standard density of the fibers to identify the type of fibers. Because density gradient liquids change with temperature, it is important to maintain a constant temperature during testing.

04 Microscopic observation method

By observing the longitudinal morphology of textile fibers under a microscope, one can distinguish the major categories to which they belong; By observing the cross-sectional morphology of textile fibers, the specific name of the fiber can be determined.

05 Dissolution method

For pure textile fabrics, during identification, a certain concentration of chemical reagents should be added to a test tube containing the textile fibers to be identified. Then, the dissolution of the textile fibers (dissolution, partial dissolution, slight dissolution, and non dissolution) should be observed and carefully distinguished, and the temperature at which they dissolve (room temperature dissolution, heating dissolution, boiling dissolution) should be carefully recorded;

For blended fabrics, when identifying them, it is necessary to first divide the fabric into individual textile fibers, then place the textile fibers on a concave glass slide, unfold the fibers, drop chemical reagents, and observe under a microscope to observe the dissolution of the constituent fibers and determine the type of fibers;

Due to the significant impact of the concentration and temperature of chemical solvents on the solubility of textile fibers, the concentration and temperature of chemical reagents should be strictly controlled when using the dissolution method to identify textile fibers.

06 Reagent staining method

The reagent coloring method is a rapid method for identifying textile fiber varieties based on the different coloring properties of various textile fibers to a certain chemical reagent. The reagent coloring method is only applicable to unstained or pure spun yarns and fabrics. Colored textile fibers or textile fabrics must be progressiveness decolorized.

Identification of the front and back, as well as the warp and weft directions of textile fabrics

01 Identification of front and back sides of textile fabrics

It can be roughly divided into identification based on the organizational structure of textile fabrics (plain, twill, satin), identification based on the appearance effect of textile fabrics (printed fabric, leno fabric, towel fabric), identification based on the pattern of textile fabrics, identification based on the edge characteristics of textile fabrics, and identification based on the appearance effect of textile fabrics after special finishing (woolen fabric, double-layer and multi-layer fabric, tattered fabric), Identify based on the trademark and seal of the textile fabric, and identify based on the packaging form of the textile fabric.

02 Identification of warp and weft directions of textile fabrics

It can be identified based on the selvage of textile fabrics, the density of textile fabrics, the raw material of yarns, the twist direction of yarns, the structure of yarns, the sizing situation, reed marks, the density, twist direction, and twist of warp and weft yarns, as well as the extensibility and shrinkage of fabrics.

Identification of Appearance Quality of Textile Fabrics

01 Identification of textile fabric defects

The defects of textile fabrics include broken warp, sinking yarn, jumping patterns, open edges, spider webs, holes, rough yarn, slub yarn, large belly yarn, double weft, tightly twisted yarn, uneven evenness, thinning, thin weft, thin section, dense path, thick section, edge defects, cotton knot impurities, stains, color stripes, crossbars, shedding, hundred feet, creases, rolling shuttles, scratches, wrong weft, loose warp, reed path, reed threading error, narrow width, diagonal reverse, pattern mismatch, color difference, color stripe, stripe, stripe mark Defects such as inconsistent patterns, fine dots in depth, skewness, printing deviation, degumming, discoloration, and staining can be identified based on the appearance characteristics.

02 Identification of deteriorated textile fabrics

The main methods are to look, touch, listen, smell, and lick:

Look: Observe the color and appearance of the fabric, and check for any signs of deterioration. Abnormal features such as wind stains, oil stains, water stains, mold spots, staining, discoloration, or normal variations in the fabric;

Touch: Grasp the fabric tightly with your hand and feel for any signs of stiffness, moisture, heat, or deterioration;

Listening: When the sound produced by tearing the fabric contrasts with the crisp sound produced by normal fabric, such as hoarse, turbid, or silent sound, it may deteriorate;

Smell: By smelling the fabric, it can determine whether it has deteriorated. Except for fabrics that have undergone special finishing (such as being coated with rainproof agents or treated with resin), any odors such as acid, mold, or bleach powder indicate that the fabric has deteriorated;

Licking: After licking the fabric with the tongue, if there is any moldy or sour taste in the flour, it indicates that it has already become moldy.

Learning these methods is not just a novice in fabric recognition. Identifying fabrics is a matter of minutes.