Standard Overview & Appearance Quality Standards
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Scope of the StandardThe GB/T 6836-2007 standard specifies the requirements for polyester, cotton, and cotton waxed sewing threads, including terminology, quality classification, testing methods, and packaging. It applies to the evaluation of thread quality in production and trade. The standard integrates and updates six previous standards, ensuring consistency with international norms like JIS L 2101 and JIS L 2511.Send Inquiry Now -
Terminology and DefinitionsKey terms such as "cotton mercerized sewing threads" (threads treated with mercerization) and "grey cotton sewing threads" (untreated threads) are defined to standardize industry language. These definitions help manufacturers and buyers communicate product specifications and performance expectations.Send Inquiry Now -
Appearance Quality StandardsThreads are graded (Premium/First/Qualified) based on surface flaws like knots, stains, or color deviations. Premium-grade threads allow zero knots per 1,000 m, while Qualified grade permits up to four. Stains are rated using gray scales (GB 251/250).Send Inquiry Now
Quality & Testing Requirements
This section details technical specifications for different thread types, including strength, twist, and defect tolerances. It also covers testing protocols to ensure compliance with grading (Premium/First/Qualified).
Testing Methods
Tests include breaking strength (GB/T 3916), linear density (GB/T 4743), and colorfastness (GB/T 3920/3921.3).
Sampling rules require 10 spools per batch for strength tests and 4 for colorfastness. Twist direction is verified via GB/T 2543.1.
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Quality Requirements for Polyester Threads
Polyester sewing threads must meet stringent criteria for breaking strength, linear density deviation, and colorfastness. For example, a 29.5 tex thread must achieve a minimum breaking force of 1,960 cN/50 cm for premium grade. The standard specifies twist direction (SZ) and tolerances for defects like knots.
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Quality Requirements for Cotton Threads
Cotton threads are classified into combed/carded, mercerized/unmercerized, and waxed variants. Breaking strength varies by ply count; e.g., a 28 tex 3-ply thread must exceed 1,200 cN/50 cm for premium grade. The standard also sets limits for twist (ZS/SZ) and tolerances for uneven dyeing.
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Compliance & Logistics
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Threads must be labeled per GB 5296.4, indicating material, tex, length, and grade. Packaging follows GB/T 4856, ensuring moisture-proofing and stackability. Special agreements between suppliers and buyers can override default rules.Packaging and Labeling -
Buyers must inspect threads upon delivery. A 5% defect rate allows replacements; >7% triggers rejection. Retesting with mutual agreement determines final compliance. Threads failing GB 18401 safety standards are non-compliant.Acceptance and Compliance -
Threads must be stored in dry warehouses (>5 cm above ground) and transported under covers to prevent moisture or heat damage. Improper storage voids supplier liability. First-in-first-out (FIFO) rotation is mandatory.Storage and Transportation
FAQ
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Is the yarn suitable for both knitting and weaving?
Yes, Polyester 65% Viscose 35% Melange Ring Spun Yarn 30/1 can be used for both knitting and weaving. -
What's the gross and net weight of each bag? How many goods can per 40HQ load?
There are 12 or 9 cones to pack each bag; each cone is 2.08kg, each bag has a net weight of 25.0kg and a gross weight of about 25.6kg. Usually a 40HQ can hold 23-24 tons. -
What are the advantages of using Polyester Recycled doped dyed Ring Spun yarn?
The advantages of using Polyester Recycled doped dyed Ring Spun yarn are that it is environmentally friendly, high quality, has a wide range of colors, and cost-effective. -
Is polyester recycled dyed ring spun yarn eco-friendly?
Yes, it is eco-friendly because it's made from recycled polyester fibers and saves valuable resources. -
What are the colors of virgin polyester yarn?
At present, we mainly produce the virgin yarn in raw white and black, and other colors need to be customized, with a minimum order quantity.