Poly Bag Film Specs: Mil, Resin, and Additives Explained

A mil is one thousandth of an inch. Gauge is another scale for the same thing. 100 gauge equals 1 mil.

• LDPE (low-density polyethylene): clear, flexible, seals well. The standard for most bags.
• LLDPE (linear low-density): tougher and more puncture-resistant at the same thickness. Lets you run thinner film for the same strength.
• HDPE (high-density): stiffer, crinkly, strong for light loads. Common in produce and deli bags.

• Anti-static: protects electronics from static discharge. Usually tinted pink.
• VCI (vapor corrosion inhibitor): releases a vapor protecting metal parts from rust.
• UV inhibitor: for bags stored outdoors.
• FDA-compliant resin: for direct food contact.

1. List the product risks. Sharp edges, weight, rust, static, food contact.
2. Pick the resin. LDPE for general use, LLDPE for puncture resistance.
3. Set the thickness. Start from the table above, then test.
4. Add additives. Only the ones your product needs.
5. Write the spec. Size, style, mil, resin, additives, color, print, and count per case.
6. Verify deliveries. Check thickness with a micrometer, or weigh a counted stack of bags against the approved sample.

Some suppliers swap in a thinner film and call the bag “equivalent.” The bag looks the same in the case. The difference shows up on the line as split seals and torn bags. A written spec and a quick weigh test catch the swap before the bags reach your packers.

Want help writing your film spec? Send us your current bag and the product.

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