The standard "ASTM D3882-08 Standard Test Method for Bow and Curvature of Woven and Knitted Fabrics" published by the American Society for Testing and Materials (ASTM) describes a test method for determining the bow and curvature of weft yarns in woven fabrics and their courses in knitted fabrics. This test method can also be used to measure the bow and curvature of printed geometric designs.
In performing the test, a ruler is placed on the fabric between the two points where the marked filler yarn, weave course, specified printed line or specified design meet two edges or selvages. The greatest distance between the ruler and the marked filler line, weave course, specified printed line or specified design is measured parallel to the selvage. The straight line distortion of the marked filler yarn, weave course, specified printed line or specified design is measured from the normal to the selvage or selvage.
This test method is considered sufficient for acceptance testing of commercial shipments.
If there are differences of practical importance between the test results reported for two laboratories, comparative tests should be carried out using competent statistical aids to determine whether there is a statistical deviation between them. At a minimum, the test samples to be used should be as homogeneous as possible, taken from material from which different test results were obtained, and randomly assigned in equal numbers to each laboratory for testing. For this purpose, other fabrics with established test values may be used.
Test results from two laboratories should be compared using a statistical test for unpaired data at a probability level chosen before the test series. If a deviation is found, the cause should be found and corrected or future test results should be adjusted to account for the known deviation.
Individual rolls are normally accepted or rejected according to the maximum amount of spring or slope in a particular roll of fabric. The average spring or slope in a roll or batch, or the range of springs or slopes in a roll, may be determined but is not normally used in the trade for acceptance or rejection.
Bowing or warping can occur during fabric production, dyeing, stretching, finishing, or other processes where there is the potential for uneven distribution of tension across the width of the fabric. Bowing and warping are more visually pleasing in colored, patterned fabrics such as plaids and horizontal stripes than in solid colors because the contrast makes the distortion more noticeable. These imperfections can lead to sewing problems in such fabrics and drape problems in the finished product. In some cases, a certain amount of warping is required to prevent the hems of trousers made of twill fabric from warping. Matching plaids from distorted patterns can present serious problems for the garment maker or home sewist. Wavy or sharp breaks in the bow line are more detrimental to the appearance of small parts of a garment (collars, pockets) than a gradual bend from a straight line.
Automotive interior textiles used for seat bolsters, cushions, headrests and door panels can be susceptible to warping and warping, especially when visually patterned fabrics are joined or bonded to a straight-edged surface.
As applicable, fabric rolls or bolts or fabric components of fabricated systems are used as the primary sampling unit. As a laboratory sampling unit, the entire roll or bolt is taken after removing the first 1 mm of length. For fabric components of fabricated systems, the entire system is used.
Three test areas are selected from each laboratory sampling unit as test samples. The first and last fifth of the roll or bolt or part length are excluded. The test areas are selected randomly but not closer than one fifth of the roll or bolt or part length.
Three test areas are selected from each sampling unit as optical test samples. The first and last 10 m of a roll are excluded and random areas within the roll are tested. Cut pieces of at least 400 mm width can be measured for springiness and warpage.
Test specimens are brought to moisture equilibrium for testing in the standard atmosphere for testing textiles in accordance with ASTM D1776 or in the atmosphere specified for testing, if any. If the loaded rolls or rolled fabrics cannot be conditioned within a reasonable time with available facilities, the test shall be conducted without conditioning and the actual condition prevailing at the time of testing shall be reported. Such results may not agree with the results obtained by testing the conditioned specimens in the standard atmosphere for testing textiles.
Our organization, which has been trying to support businesses from every sector with its wide range of testing, measurement, analysis and evaluation studies for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services are also provided to businesses in accordance with the "ASTM D3882-08 Standard test method for bending and warping in woven and knitted fabrics" standard.
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