Bag Sewing Thread Characteristics
Following is a list of bag sewing thread characteristics that maybe taken into consideration to determine the appropriate thread you will need for your application. For assistance in determining the best thread for your specific application contact us
Certification: Some applications may require the thread to be certified for a specific use. The FDA, GSA, and U.S. military agencies have regulations for specific sewing applications. For example, FDA 21CFR174-179 is a requirement for thread lubricant to meet the safety requirements for food additives.
Color: For esthetic reasons, thread is offered in a number of colors (e.g., white, red, blue, green, and yellow).
Density: (Strand Coarseness) Strand density is measured in DTEX units. DTEX is a measurement of weigh (grams) per unit of length (10,000 meters). The lower the DTEX number, the finer the strand; and the higher the DTEX number, coarser the strand.
Knots: Knots created in the manufacturing process can cause the thread to brake as it passes through the sewing head’s guides. A good quality thread will have no knots/cone.
Lubricant: Threads often contain lubricants to make them easier to sew and decrease breakage. 10% silicone is a typical thread lubricant. Note: some applications (e.g., food products) may require an agency certification.
Material: For most bag sewing applications, thread is offered in four materials listed here in decreasing strength: Nylon (strongest), polyester, polyester/cotton blend, and cotton (weakest).
Melting Point: The melting point (m.p.) of a thread can determine the environment it is used in and the speed of production. In high production areas a thread with a low melting point many break while sewing due to friction through the guides. For example, a cotton thread may have a 3000F m.p. and a polyester thread have a 5000F m.p.
Packaging: Thread is typically wrapped on cylinders or tapered cones. While cones containing less thread then a comparable cylinder, cones facilitate easier thread removal with less breakage.
Strength: The thread’s strength is determined by the material, thickness, number of plies, and twists/inch. The strength of the thread is measured by its tensile strength (breaking force). A typical polyester 12/4 thread has a tensile strength of 17 lb.
Stretchablity: Elongation Break (EB) is a measurement of a thread’s strechability and is expressed as a percentage increase that a thread will stretch before it breaks. For example, a 12” thread with an EB of 25% will stretch to 15” before it breaks.
Thickness & Plies: Industrial bagging thread is designated by its thickness and the number of plies (e.g. 12/4). The first number represents the thickness of the thread and is measured as yards/lb. A #12 cotton thread has 10,080 yds./lb. A #12 thread is 2x coarser than a #24 thread. The second number represents the number of plies or wrapped strands. A 12/4 thread has 4 strands.
Twists/Wraps: The number and the direction of the twists of a multi strand thread also determine the tensile strength. Generally, the more twists/inch the stronger and stiffer the thread. A 12/4 polyester thread has a tensile strength of 17 lb.; while a 12/5 polyester thread has a tensile strength of 19 lbs. Note: a high number of twists may cause the thread to coil and as a result, be harder to feed through the sewing head’s guides.
UV Protection: A good quality thread will have some kind of UV protection added to reduce degradation.
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