"Zip lock" and "smell proof" get used like they mean the same thing. They don't. A zip lock bag just describes the closure — a plastic track that presses shut. Whether that bag actually holds odor in, blocks light, or survives being opened a hundred times depends entirely on what it's made of and how it's built.
Here's where the two actually diverge, and which one you need for cannabis.
🔒 What "Zip Lock" Actually Promises
A zip lock bag guarantees exactly one thing: a plastic zipper that closes. That's it. The classic sandwich-bag style zip lock is usually:
Thin, single-ply plastic — fine for keeping crumbs off a sandwich, not built to block odor molecules.
Clear — which means UV light passes straight through, degrading cannabinoids and terpenes over time.
A single-track zipper — it closes, but it's not designed to hold pressure evenly across a full seal.
None of that makes a bag bad — it just means "zip lock" was never a smell proof spec to begin with. It's a closure style, not a barrier standard.
🌬️ What "Smell Proof" Actually Requires
A true smell proof bag has to do three things a basic zip lock never promises:
Block the odor molecules from passing through the material itself — which means a multi-layer barrier film, not thin single-ply plastic.
Seal edge-to-edge under pressure — a double-track zipper distributes closure force evenly, so there's no gap for smell to escape.
Stay sealed after repeated use — hundreds of open-close cycles without the seal degrading.
Kure Bags builds every size around all three: black opaque barrier film, a reinforced double-track zipper, and the FlavrSavr™ System holding 58–62% relative humidity so flower doesn't dry out or mold in storage.
📦 So Which One Do You Actually Need?
Packing a lunch or storing crackers? A basic zip lock bag is genuinely fine.
Storing or transporting cannabis? You need a real smell proof bag — barrier film, double-track zipper, opaque construction. A kitchen zip lock won't hold odor in past a few hours, and it won't protect potency at all.
The mistake most people make isn't picking the wrong size — it's assuming any bag with a zipper qualifies as smell proof. It doesn't. The material behind the zipper is what actually does the work.
Browse Kure Bags' full smell proof lineup →
❓ FAQs
Q: Are zip lock bags smell proof at all?
A: Not reliably. Thin, single-ply plastic and a single-track zipper let odor escape over time, even when the bag looks sealed.
Q: What makes a bag actually smell proof?
A: A multi-layer barrier film material combined with a double-track zipper that seals evenly under pressure — not the presence of a zipper alone.
Q: Can I reuse a smell proof bag as many times as a zip lock bag?
A: A well-built smell proof bag actually outlasts a basic zip lock — the reinforced double-track zipper is designed for hundreds of reseals without losing its grip.