Differences Between 12/4 and 12/5 Polyester Bag Sewing Thread & Selection Guide
- 4 days ago
- 2 min read
Both 12/4 and 12/5 are widely used industrial 100% polyester bag sewing threads. They share the same single‑yarn count, while their core difference lies in the number of plies, which directly affects thread thickness, tensile strength, wear resistance and application scenarios. It is an essential reference for packaging industry selection.
1. Basic Structure & Specification Difference
The number “12” stands for Ne12 English cotton count, meaning the thickness of single raw yarn is identical. The last digit indicates the number of twisted plies: 12/4 is 4‑ply twisted thread, while 12/5 is 5‑ply twisted thread.
With one extra ply, 12/5 features a thicker diameter and denser structure. Under the same material and production process, 12/5 is heavier and sturdier, whereas 12/4 is slimmer and softer.
2. Physical Performance Differences
Breaking Force: 12/4 has an average breaking force of around 8.0 kg for regular load‑bearing use; 12/5 achieves 9.5–10.5 kg with stronger tensile resistance, avoiding thread breakage.
Softness & Smoothness: With fewer plies, 12/4 runs more smoothly for high‑speed sewing and rarely causes machine jams. 12/5 is stiffer and requires higher tension adjustment for bag closer machines.
Wear Resistance: Thicker 12/5 delivers better wear and friction resistance for harsh conditions and long‑term storage. 12/4 meets wear‑resistant demands for daily handling.
3. Application & Usage Scenarios
12/4 Polyester Bag Sewing Thread (Standard General‑Purpose Grade)
It is the mainstream universal grade for medium‑light load and high‑efficiency high‑speed sewing.
Suitable for regular packaging bags under 40 kg, such as sugar bags, common PP woven grain bags and medium‑small feed bags. Compatible with mainstream high‑speed portable bag closers including Newlong, Fischbein, Union‑Special and JUKI. Widely applied in grain, food and light‑industry packaging production lines requiring neat stitching and high efficiency.
12/5 Polyester Bag Sewing Thread (Heavy‑Duty Reinforced Grade)
Designed for high load‑bearing, heavy‑duty and high‑wear packaging needs.
Ideal for heavy‑duty bags of 40–80 kg, including fertilizer bags, cement bags, thick sand‑stone construction material bags and industrial raw material bags. Matched with high‑power heavy‑duty bag closing machines. Used for outdoor storage, frequent transportation and rough‑material packaging to prevent stitching tearing and material leakage during handling and stacking.
4. Selection Advice
Choose 12/4 for regular grain, sugar and common feed packaging for cost‑effectiveness. Select 12/5 for fertilizer, construction material, heavy‑weight industrial packaging or long‑term outdoor storage. Avoid misapplication: thin thread for heavy bags easily breaks, while thick thread may damage lightweight bags and cause thread waste.
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