How to choose Airtight Zippers for Vacuum Bags

Nylon airtight zippers are critical for negative pressure sealing of vacuum storage bags, differing from diving & outdoor waterproof zippers. Here are 6 selection tips: 1. Air Tightness & Pressure Retention Waterproofing is not required. Focus on long-term air retention after vacuuming. Test: Closed zipper under negative pressure, no obvious rebound or bulging after 24h standing. 2. Workmanship & Appearance - TPU film: Smooth, no bubbles or particles, uniform distribution - Zipper teeth: Straight, symmetrical meshing when closed - Tape: Burr-free clean cut; film tightly bonded, no warping or delamination 3. Sizes #3, #5, #8 available. Larger size means thicker teeth and stronger pressure resistance. Recommend #5+, #8 preferred; #3 is not advised. 4. Smooth Pulling Performance Airtight zippers have higher pulling resistance. Good zippers slide smoothly with no skipped teeth or jamming. Fully locked zipper won’t be pried open by vacuum negative pressure. 5. Lamination & Bonding Process Film base material decides lamination stability. High-grade TPU/PVC film has uniform texture and stable heat resistance, achieving high-frequency thermal fusion with nylon tape. 6. Certifications & Reports Export: REACH, PFAS-free. Bonus: ISO9001, OEKO‑TEX Standard 100. Use traceable test reports, not verbal commitments. Quick Summary: Prioritize pressure retention, smooth pull and stable lamination. Match the right size and traceable reports to achieve long service life and reliable leak-proof performance.