Commonly used textile shrinkage, physical properties, color fastness, chemical properties test

Shrinkage test
1) Objective: To determine the dimensional stability of woven or knitted fabric after repeated washing by household washing machine.

2) Principle: Before washing, mark the size on the sample, and judge the size change of the sample by measuring the change of the mark after washing.

3) Process: Select washing and drying methods, cycles and drying times according to cloth types and customer requirements, add standard detergent and appropriate water level to start washing and drying, and finally obtain test results.

1) Main projects:

Yarn count, density, gram weight, tensile strength, tearing strength, seam slip, seam strength, bursting strength, wear resistance, pilling resistance, etc.
2) Specific instructions:

Yarn count: refers to the thickness of the yarn, currently used mostly in imperial count, expressed by Ne, which is defined as a multiple of 840 yards of length of 1 pound cotton yarn thread at a common moisture return rate of 9.89%.
Density: Number of threads per inch.
Gram weight: ounces per square yard of cloth or grams per square meter of cloth.
Tensile strength: The force used by the tensile strength machine to stretch a certain size of fabric at a constant rate to break is the measured tensile strength. Tensile strength test has grab sample method and strip sample method, according to different test standards and customer requirements to choose the specific test method.
Tear strength: The sample of a certain size is clamped on the tear strength meter, and all holes are cut in the middle to determine the tear direction. The force used by the tear strength meter to tear the sample from the incision is the measured tear strength.
Seam slip: After folding a certain size of fabric, sewing the seam along the width direction, and cutting it at a certain distance from the seam, using the tensile strength meter to stretch the force used to stretch the seam opening at a constant rate or the opening distance when stretching to a certain strong force is the seam slip measured by us. There are two ways of measuring joint slip: fixed opening and fixed opening. The specific test method is selected according to different test standards and customer requirements. Seam slip is generally only used for testing woven fabric.

Seam strength: The same as seam slip, after folding a certain size of fabric, sewing line along the width direction, and cut a certain distance from the seam line, the force used to stretch the suture line at a constant rate is the measured seam strength, and the seam strength can be carried out at the same time as the seam slip, generally only for the test of woven fabric.

Bursting strength: under certain conditions, a flat fabric is rotated at a suitable Angle to add an expansive expansion force until it breaks, this force is bursting strength.

Wear resistance: under known pressure, the degree sample installed on the sample clip and the standard friction cloth rub each other in a certain track under a certain pressure until the fabric appears the number of broken yarn or holes required by the customer, and record the number of friction at the end of the experiment, which is the measured wear value.

Pilling resistance: The fabric is rolled and rubbed under specific conditions for a certain time, and the surface pilling situation is watched. Pilling refers to the pilling cluster formed by the fiber entanglement standing on the surface of the fabric. Fuzz refers to the roughness and/or fuzz of the fabric surface, resulting in changes in the appearance of the fabric, and its fuzz and pilling is assessed by rating sample or as-is comparison.

Color fastness test
1) Main projects:

Washing color fastness, dry cleaning color fastness, rubbing color fastness, sun fastness, perspiration stain color fastness, water stain color fastness, chlorine bleaching color fastness, non-chlorine bleaching color fastness, hot pressing color fastness.
2) Basic content:
Washing color fastness: The sample is stitched together with the standard lining fabric, washed, cleaned and dried, and washed under the right temperature, alkalinity, bleaching and friction conditions, so that the test results are obtained in a short time. The friction between them is accomplished by the small bath ratio and the appropriate number of stainless steel beads rolling and bumping, and finally the standard lining fabric and the sample color fastness of the special gray card is rated, the test results are obtained. Different test methods have different temperature, alkalinity, bleaching and friction conditions and sample size, specific according to the test standards and customer requirements to choose. Generally, the color fastness of water washing is poor, such as Turquoise, brilliant blue, black red, navy blue and so on.

Dry cleaning color fastness: the same as washing color fastness, only wash to dry cleaning.
Friction color fastness: Put the sample on the friction fastness meter, and rub the standard friction white cloth with it for a certain number of times at a certain pressure. Each group of samples should be made of dry friction color fastness and wet friction color fastness. The color of the standard friction white cloth is rated with a gray card, and the resulting series is the friction color fastness measured. Rubbing color fastness requires both dry and wet rubbing tests, and all colors on the sample should be rubbed to.

Fastness to sunlight: Textiles are usually exposed to light when used, light can destroy the dye and lead to the well-known "fading", so that colored textiles change color, generally light, dark, some will also appear color light change, so it is necessary to test the color fastness, sun fastness test, That is, the sample and the blue wool standard cloth with different fastness levels are placed together under the specified conditions for sunlight exposure, and the sample is compared with the blue wool cloth to evaluate the light fastness. The higher the blue wool standard cloth level, the more light fast.

Perspiration stain color fastness: the sample and the standard lining fabric are stitched together, placed in the perspiration stain solution, clamped on the perspiration stain color fastness meter, placed in the oven at constant temperature, and then the sample lining fabric is dried separately. Finally, the standard lining fabric and the sample color fastness special gray card are rated to obtain the test results. Different test methods have different perspiration ratio, different sample size, different test temperature and time.

Water stain color fastness: the sample and the standard lining fabric are stitched together, soaked in water under certain conditions, clamped on the color fastness meter to sweat stain, placed in the oven at constant temperature, and then the sample lining fabric is dried separately, and finally the standard lining fabric and the sample color fastness special gray card are rated to obtain the test results. Different test methods have different sample sizes, different test temperatures and times.

Chlorine bleaching fastness: After the fabric is washed in chlorine bleaching solution under certain conditions, the degree of color change is assessed, which is the chlorine bleaching fastness.

Non-chlorine bleaching fastness: After the fabric is washed under washing conditions with non-chlorine bleaching, the degree of color change is assessed, which is non-chlorine bleaching fastness.

Hot press color fastness: After the dry sample is covered with cotton backing fabric, it is pressed in a heating device at a specified temperature and pressure for a certain period of time, and then the color change of the sample and the stain of the backing fabric are evaluated with a gray sample card. Hot pressing color fastness has dry pressing, tidal pressing, wet pressing, specific according to different customer requirements and test standards to choose the test method.

Chemical property test
1) Main test items:

Formaldehyde test, pH test, water repellent test, oil repellent test, antifouling test, flame retardant test, fiber composition analysis, prohibited azo dye test, etc.
2) Basic content:

Formaldehyde test: Extract free formaldehyde or released formaldehyde from a certain amount of fabric in a certain way, and then calculate the formaldehyde content through colorimetric testing.

Now on the market, textile products can improve the wrinkle resistance of products by resin finishing, this resin finishing agent is directly synthesized from formaldehyde, so a certain amount of formaldehyde will remain in the fabric finished by these resins. In addition, in order to improve the dyeing fastness, the crosslinking agent in the pigment printing paste and the fixing agent used after dyeing with direct dyes and reactive dyes will cause a certain amount of formaldehyde to remain on the clothing material. These formaldehyde can be determined by certain test methods.

pH test: Use a pH meter to accurately measure the acidity and alkalinity of the fabric solution, and the value read out on the pH meter is the pH value measured.

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

Flame retardant test: the sample is burned on the flame retardant tester according to the regulations, and the flame spread time is seen.

Fiber composition analysis: First of all, qualitative analysis of the fibers of the fabric is carried out, and there are many kinds of qualitative analysis, including combustion method, melting point method, hand visual method, microscope section analysis, etc. Generally, microscope section analysis is adopted, that is, the fiber is sliced with a slicer and observed under a microscope, according to its appearance, the types of fibers are determined, and then qualitative analysis is carried out with different solvents according to different fibers. Figure out the specific ingredient content.

Forbidden azo dye test: it is the most important quality control project in the international textile and clothing trade, and one of the most basic quality indicators of ecological textiles, which is mainly analyzed and tested by gas chromatograph. Azo dye test is divided into three methods, textiles (except polyester and leather textiles), polyester (polyester), leather (leather), so do azo test must provide the composition of the product.