Resealable Mylar Bags

Resealable Mylar Bags: Keeping Products Fresh Between Uses

The moment a customer opens a bag of coffee, herbs, snacks, or cannabis, the race against freshness begins. Oxygen enters, moisture may follow, and the barrier that protected the product during packaging is compromised. A resealable mylar bag slows this process dramatically. The zip lock closure allows the customer to seal the bag again after each use, maintaining significantly better freshness than an unsealed open bag.

Resealable mylar bags are the standard format across most consumer-facing flexible packaging categories precisely because they work: they genuinely extend the freshness of the product across multiple use occasions.

How Resealable Closures Work

The most common resealable mechanism on mylar bags is the zip lock: a pair of interlocking plastic (usually PE or PP) profile strips heat-welded or adhered into the bag just below the fill area. Pressing the two sides of the zip together locks them. Pulling them apart opens them.

This allows a simple open-and-close cycle that requires no tools, no special technique, and no additional packaging (like clips or bands). For the consumer, it's the most convenient reseal option available on flexible packaging.

Types of Resealable Closures

Standard euro-slot zip: The most common. A single zip track that press-closes with finger pressure along the length of the closure. Works well for most dry goods, supplements, and food products.

Double zip: Two zip tracks for extra security. Common on premium or moisture-sensitive products where double sealing is worth the additional cost.

Child-resistant press-to-close: A modified zip design that requires simultaneous pressure at two points (usually two small depressions at the sides of the zip) to open. Meets child-resistance certification standards and is required in cannabis retail markets.

Velcro-style adhesive strip: An alternative to the zip lock using a pressure-sensitive adhesive reclosure strip. Less common but used in some pharmaceutical and industrial applications.

Tin tie: A metal wire sewn into the top fold of the bag that can be twisted shut. Popular for coffee bags; provides a reclosure that requires no special mechanism but is less airtight than a zip.

How Well Do Resealable Closures Actually Work?

A resealable zip lock significantly reduces the rate of freshness degradation compared to an unsealed open bag, but it's not the same as the original hermetically sealed condition. Oxygen will slowly exchange through the zip lock over time, particularly if the zip track is not pressed closed with full pressure across its entire length.

For products where every hour of freshness after opening matters (specialty coffee, cannabis, volatile aromatics), some consumers use additional clip seals or binder clips across the zip after closing, which helps. Others decant the product into a separate airtight container.

For most practical purposes, a properly closed zip lock on a quality foil laminate bag extends post-opening freshness from days (unsealed) to weeks (reseal zip).

Applications for Resealable Mylar Bags

Resealable closure is appropriate for any product used in multiple portions over time:

- Coffee and tea (consumed over days or weeks)

- Protein powder and nutritional supplements (consumed over weeks)

- Cannabis flower (consumed over multiple sessions)

- Snacks and dried fruit (shared or portion-controlled)

- Spices and herbs (used in small amounts per cooking occasion)

- Pet treats (given one at a time)

- Cosmetics (used in small amounts per application)

For single-use products consumed in one sitting, a heat-seal-only (non-resealable) bag is adequate and lower cost.

Design and Printing

The zip lock area of a resealable bag occupies approximately 1.5 to 2 cm at the top of the bag interior, which is a structural element rather than a design element. Printing designs should account for the zip position and avoid placing key design elements too close to the top of the bag.

The zip lock itself is usually a natural PE colour (white or natural), which blends into the bag. Some premium bags have coloured zip locks that match the brand colour palette.

Buying Resealable Mylar Bags

For brands building custom packaging, resealable zip lock is a standard option available on virtually all mylar pouch formats: stand-up pouches, flat seal bags, gusseted side-seal bags, and others.

At TheCardBoardBoxes, resealable mylar bags are produced in all sizes and formats with full custom printing. Zip lock closure is available in standard and child-resistant versions. Minimum orders start at 500 units, with fast UK turnaround.