Basic knowledge of textile and Garment Inspection and Testing

1 Shrinkage test

1) Objective: To determine the dimensional stability of woven or knitted fabrics after repeated washing by household washing machines.

2) Principle: The size of the sample is marked before washing, and the size change of the sample is determined by measuring the change of the mark after washing.

3) Process: Select the washing and drying method, cycle and drying times according to the cloth species and customer requirements, add standard detergent and appropriate water level to start washing and drying, and finally get the test results.

2 Physical performance test

1) Main Projects:

Yarn count, density, gram weight, tensile strength, tear strength, joint slip, joint strength, bursting strength, abrasion resistance, pilling resistance, etc.

2) Details:

Yarn count: refers to the thickness of the yarn, most of which is in English, denoted by Ne, which is defined as 840 yards of the length of a 1-pound cotton yarn at a common fixed moisture regain rate of 9.89%.

Density: number of threads per INCH.

Gram weight: ounce of cloth per square yard or gram of cloth per square meter.

Tensile strength: The tensile strength measured is the force used when a fabric of a given size is stretched to breaking by a tensile strength machine at a constant rate.The test of tensile strength consists of grabbing method and strip method. The specific test method is selected according to different test standards and customer requirements.

Tear strength: a sample of a certain size is clamped on the tear strength tester and cut all the holes in the middle to determine the tear direction. The tear strength used by the tear strength tester to tear the sample from the incision by means of pendulum drop is the measured tear strength.

Seam slip: after folding a fabric of a certain size and cutting it along the width and a certain distance from the seam, the tensile strength meter is used to stretch the fabric at a constant rate to a certain seam opening or the opening distance when stretching to a certain strength, which is the joint slip measured.There are two ways of joint slip: fixed opening and fixed opening. The specific test method is selected according to different test standards and customer requirements.Joint slip is generally only used for testing woven fabrics.

Joint strength: as with seam slippage, to a certain size after folding the fabric, stitching along width direction, cut open after a certain distance away from the joints and using tensile strength tester with constant rate tensile suture disconnect the joint strength of the force is measured used, joint strength can be done in conjunction with seam slippage, generally used only for woven fabric test.

Bursting strength: Under certain conditions, an expansive expansive force is applied to a flat fabric at a suitable Angle until it breaks.

Abrasion resistance: under a known pressure, the sample mounted on the sample clip and the standard abrasive cloth rub against each other with a certain track under a certain pressure until the fabric has the number of broken yarn roots or holes required by the customer. The abrasion resistance value measured at the end of the experiment is recorded.

Pilling resistance: Roll and rub the fabric under certain conditions for a certain time, and watch the pilling on its surface. Pilling refers to the pile balls formed by the tangled fibers standing on the surface of the fabric.Fluffing refers to the roughness and/or fluffing of the fabric surface fibers, which results in a change in the appearance of the fabric. Fluffing is evaluated by grading samples or comparison of the original samples.

3. Color fastness test

1) Main Projects:

Colour fastness to washing, dry cleaning, rubbing, sun, sweat, water, chlorine, non-chlorine, hot pressing, etc.

2) Basic Contents:

Colour fastness to washing: The sample is sewn together with the standard lining fabric, washed, cleaned and dried, and washed under appropriate temperature, alkalinity, bleach and friction conditions, so that the test results can be obtained in a relatively short time.The friction effect was completed by the rolling and bumping of a small bath ratio and an appropriate number of stainless steel beads. Finally, the special grey CARDS for color fastness of standard lining fabrics and samples were graded and the test results were obtained.Different test methods have different temperature, alkalinity, bleaching and rubbing conditions and sample sizes, which are selected according to test standards and customer requirements.Generally, the color fastness of washing is poor, such as cui LAN, Yan LAN, black red, navy blue, etc.

Dry cleaning color fastness: same as washing color fastness, just wash to dry cleaning.

Color fastness to friction: Put the samples on the friction fastness meter and rub them with standard friction white cloth for a certain number of times at a certain pressure. The color fastness to dry friction and wet friction should be done for each group of samples.The color on the standard friction white cloth is rated by grey card, and the series obtained is the measured color fastness to friction.The color fastness to rubbing should be tested by both dry and wet rubbing. All the colors on the sample should be rubbed.

When use sunlight fastness: textiles are often exposed to light, the light damage dye which leads to the well-known "fade", discoloring the coloured textiles, generally becomes shallow, dark, some will appear color change, so it need to test color fastness to sunlight fastness test, the sample is with different fastness standard series of blue wool cloth in the sunlight exposure under specified conditions, the sample compared with blue wool cloth, to evaluate the color fastness to light, blue wool cloth series standard, the higher the more light.

Color fastness to sweat stain: The sample was stitched together with the standard lining fabric, put in the sweat stain solution, clamped on the color fastness meter, put in the oven at constant temperature, and then the lining fabric of the sample was dried separately. Finally, the standard lining fabric and the color fastness of the sample were rated, and the test results were obtained.Different test methods have different ratio of sweat stain, different sample size, different test temperature and time.

Stain color fastness: the sample and standard affixed lining fabric stitch together, on certain conditions fully after soaking in water, clip on the color fastness to perspiration tester, put in the oven temperature, the sample and then affixed lining fabric drying respectively, finally, the standard for lining fabric and sample color fastness special gray card, test results are obtained.Different test methods have different sample size, different test temperature and time.

Color fastness to chlorine bleaching: After washing the fabric in chlorine bleach solution under certain conditions, the color change of the fabric is evaluated. This is the color fastness to chlorine bleaching.

Non-chlorine colour fastness: The colour of the fabric is evaluated after being washed under non-chlorine washing conditions. This is non-chlorine colour fastness.

Color fastness of hot pressing: after the dry samples are covered with cotton lining fabric, they are pressed in the heating device of specified temperature and pressure for a certain period of time, and then the color discoloration of the samples and the color of the lining fabric are evaluated with a gray card.The color fastness of hot pressing includes dry pressing, wet pressing and wet pressing. The test method should be selected according to different customer requirements and test standards.

4. Chemical performance test

1) Main test items:

Formaldehyde test, pH test, water repellent test, oil repellent test, antifouling test, flame retardant test, fiber component analysis, banned azo dye test, etc.

2) Basic Contents:

Formaldehyde test: the free formaldehyde or released formaldehyde in a certain amount of fabric can be extracted in a certain way, and then the formaldehyde content can be calculated by colorimetric test.

In the current market, textile products can improve the wrinkle resistance of products through resin finishing, this resin finishing agent is directly synthesized by formaldehyde, so the fabric after these resin finishing will remain a certain amount of formaldehyde.In addition, in order to improve the fastness of dyeing, the cross-linking agent in the pigment printing paste and the fixing agent used after dyeing with direct dyes and reactive dyes will leave a certain amount of formaldehyde on the garment materials.These formaldehyde can be determined by certain test methods.

PH test: The acidity or alkalinity of the fabric solution is measured accurately with a pH meter, and the value read on the pH meter is the measured pH value.

Water-repellent, oil-repellent and antifouling test: the resistance of the fabric to water, oil and stains is measured in a certain way, mainly for the cloth seed after three anti-finishing.

Flame retardant test: put the sample on the flame retardant tester according to the regulation for combustion, see the flame spread time.

Fiber component analysis: first of all fabric fiber qualitative analysis, qualitative analysis is more than good, a combustion method, melting method, the feel is visual observation, microscopic section analysis method and so on, generally using the method of microscope slides, the box slicer will slice under the microscope, fiber according to its appearance, judge fiber types, and then according to the different fiber with different solvents for qualitative analysis, calculate the specific content.

Banned azo dye test: it is the most important quality control item in the international textile and garment trade, and it is also one of the most basic quality indexes of ecological textiles. At present, it is mainly analyzed and tested by gas chromatograph.Azo dye testing is divided into three methods: textiles (except polyester and leather), polyester (polyester), leather (leather), so when doing azo testing must provide the ingredients of the product.

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