<h1>How to inspect bulk fabrics？</h1>
Before the mass production of garments, there are often various problems with the fabrics sent to the factory, such as uneven edges, dye irregularities, and color differences between batches. The causes of these issues are multifaceted. Experienced quality control (QC) personnel will remind the fabric manufacturer to self-inspect various parameters before shipping the bulk materials, in order to minimize the potential for problems during the production process. It is crucial to identify and resolve issues promptly, so that the garment factory’s production plan is not disrupted.
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<strong>Fabric inspection procedures and standard reference:</strong>
<ul>
<li><strong>Before inspection</strong>, review the packing list and related documents. If there are any doubts, clarify them with the provider. Confirm that there are no issues, and bring the documents and necessary inspection tools.</li>
<li><strong>Prior to sampling</strong>, check if the goods are correct and meet the inspection standards. 100% of the goods must be received.
Sampling quantity: Take the square root of the number of rolls, boxes or rolls delivered.
Sampling length: Take the square root of the total length to be inspected, and multiply by 8.
For color difference between dye lots, if the dye lot information is provided on the packing list, the inspector must sample all the dye lots and compare the colors. If there are more dye lots than the number of rolls sampled, the inspector must sample all the dye lot rolls and compare the color of the head samples from the rolls not inspected for quality.
The inspector must verify that the fabric manufacturer’s practices comply with the order requirements.</li>
<li><strong>Inspection process</strong>:
Visual inspection can be conducted on a warp inspection machine, with the inspection table at a 65-degree angle to the horizontal, and avoiding direct sunlight and white light reflection.
Visual inspection can also be done on an inspection table, as a supplement when a warp inspection machine is not available. The table height should be 0.95m and the length should be at least 3m, wider than the fabric width.
The lighting should be overhead fluorescent lamps (daylight, 6500K color temperature). The inspection machine speed should be 20 yards/minute, adjustable by the inspector.
The inspector should stand in front of the inspection table, about one yard away from the center of the fabric. For fabrics wider than 50 inches, two inspectors are required; for narrower fabrics, one inspector is sufficient. The inspector can stop the machine to record any defects found.
The visual inspection covers: fabric defects such as weaving, dyeing, and printing; general appearance, structure and materials; color, width, roll length, warp bow and weft skew, packaging and labeling.
The appearance can be checked against the customer’s reference sample, focusing on style, pattern and effect, with at least one full repeat of printed or jacquard patterns.
For structure, fiber content, yarn type and count can be tested if required by the customer.
For hand feel, compare the fabric samples to see if they are hard or soft, thick or thin. If there are obvious differences, note it in the report and mark it as non-conforming. Collect samples with different hand feel for comparison, if possible.</li>
</ul>
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<strong>Common fabric defects: </strong>Double warp, coarse warp, broken warp, coarse weft, double weft
<ul>
<li><strong>Loose warp</strong>: The loosened or broken warp yarns are gradually woven into the fabric</li>
<li><strong>Hanging warp</strong>: In woven fabrics, a warp yarn is abnormally tightened due to excessive tension, in knitted fabrics it can cause sparse paths or distortion of the warp-wise patterns</li>
<li><strong>Missing weft</strong>: Lack of a weft yarn in the fabric structure</li>
<li><strong>Broken weft</strong>: Transverse breakage of weft yarns in the fabric</li>
<li><strong>Horizontal stripe</strong>: A trace that is clearly different from the fabric characteristics in terms of chemistry or material across the entire width of the fabric</li>
<li><strong>Foreign matter woven in</strong>: Floating fibers are incorporated into the yarn or woven into the fabric</li>
<li><strong>Big belly yarn</strong>: A yarn with a thick and thin section</li>
<li><strong>Yarn knot</strong>: Fibers are heavily entangled to form a knot</li>
<li><strong>Weft skew</strong>: In knitted fabrics, the weft yarns are not perpendicular to the warp yarns, and the courses are not perpendicular to the wales</li>
<li><strong>Dropped stitch</strong>: Holes formed in knitted fabrics due to needle failure</li>
<li><strong>Run</strong>: Large-scale structural damage caused by equipment failure in knitting</li>
<li><strong>Dense/sparse path</strong>: Denser or sparser weft insertion in the transverse direction of the fabric</li>
<li><strong>Needle mark</strong>: Longitudinal splitting caused by the curved needle in knitted fabrics</li>
<li><strong>Hole</strong>: Regardless of the size of the damage</li>
</ul>
<strong>Color difference evaluation:</strong>
Checking the color difference of fabrics is very important, second only to the inspection of surface defects. According to the form of expression, it can be divided into color difference between rolls, dyebath difference between batches, head-middle-tail difference and edge-center-edge color difference within the same roll.
According to the production process, it can be caused by different yarn batch numbers, bleaching process, dyeing time, temperature and pressure, different printing paste, different density in weaving, different embroidery thread color. These color differences may exist alone or several at the same time, depending on the different processes used in production.
The inspector needs to carefully check the possible color differences. If the fabric factory cannot control the color difference within a certain range, it will bring great difficulties to the cutting of the garment factory.
Evaluation of color change using the gray scale card is based on the GB250-1995 standard, commonly known as the "gray card". This is equivalent to ISO105-A02:1993 and BS EN20105 A02:1995.
<strong>Method for using the gray card</strong>:
Place the original fabric sample and the production sample side by side, oriented in the same direction and in close proximity. The gray card should also be placed on the same plane. The background should be a neutral gray color, approximately between grade 1 and grade 2 of the gray card.
To avoid the influence of the backing on the appearance of the textile, an extra layer or more of the original fabric can be used as padding between the original and tested samples to assess the color difference.
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<strong>AATCC Greyscale for Color Change</strong>
During the fabric inspection process, a 6-inch to 10-inch wide sample is taken from the head of each roll. These samples will be used by the inspector to compare color differences within the same roll or between different rolls.
<strong>Acceptable ranges for different color differences</strong>:
<strong>Batch or Dye Lot Difference:</strong>
The commercial acceptance level is usually when the color difference between two dye lots is above grade 4 on the gray card (Commercial acceptance: 2 Dye Lots above Grade 4).
The color difference between rolls or batches should not be below grade 4 on the gray card. If it is below grade 4 or there are more than two dye lot differences, it needs to be recorded as non-conforming in the color column of the report.
If the fabric being inspected deviates from the previously provided approval sample, the color difference within the production and between the production and the standard sample should be above grade 4.
<strong>Acceptable range for color difference within the same roll</strong>:
The color difference from edge to edge, edge to center, or head to middle to tail of the same roll should not be below grade 4-5 on the gray card. If it is grade 5, it does not need to be specified. If it is grade 4-5, it can be accepted but needs to be noted in the report.
If it is grade 4 or below, the roll is considered as grade B. The color difference from head to middle to tail should be checked by taking samples during the inspection process.
<strong>Recording method</strong>:
<ul>
<li>Deviations at grades 5, 4-5, 4 can be recorded as Slightly Lighter, Darker, Brighter, Duller (acceptable).</li>
<li>Deviations at grades 3-4 can be recorded as Lighter, Darker, Brighter, Duller (unacceptable).</li>
<li>Deviations at grades 3, 2-3, 2, 1-2, 1 can be recorded as Noticeably Lighter, Darker, Brighter, Duller (unacceptable).</li>
<li>If the color tone is different, it can be recorded as Different Color Tone (acceptance depends on the dye lot grade).</li>
</ul>
<strong>Acceptable range for fabric length</strong>:
If the actual length of the fabric is more than 1% shorter than the labeled length, the fabric is considered as grade B. Generally, factories will mark major defects and cut the fabric accordingly, so the actual length is usually longer than the labeled length.
At least five rolls of fabric should be measured for length in each inspection. If a roll is found to be out of the acceptable range, every three rolls thereafter should be measured for length. The acceptable range for warp skew and bow is 3%.
For joined fabric: If a roll contains a joined section shorter than 30 yards, the roll is considered non-conforming.
Fabric odor: Any roll emitting an unpleasant odor is considered grade B.
<strong>After inspection</strong>:
At the inspection site, the inspection report should be carefully filled out. The report can be provided to the client when necessary. Packaging materials should be sampled and retained, and the inspection time should be noted on the report, which should be signed.
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