How to Heat-Seal Mylar Bags: A Step-by-Step Guide

A heat seal is what turns a mylar bag from “a bag” into retail-ready, smell-proof packaging. Done right, it locks in freshness and aroma and gives your product a professional finish. Done wrong, it leaks, wrinkles, or burns through the film. Here’s how to do it right.

What you’ll need

• Your mylar bags (filled and ready to seal)
• A heat sealer — an impulse sealer for occasional runs, or a continuous/band sealer for volume
• A flat, clean work surface

Step 1: Pick the right sealer

For small batches, an impulse sealer (it heats only when you press down) is affordable and reliable. For high volume, a continuous band sealer keeps a steady temperature and seals bag after bag without cooldown. Both work with our retail-grade mylar.

Step 2: Set your temperature

Thicker films need more heat. Start on a medium setting and run a test seal on an empty bag first. The seal should be flat and fused — not bubbled, browned, or melted through. Adjust up if the seam pulls apart, down if the film distorts.

Step 3: Fill, then leave headspace

Don’t overfill. Leave about half an inch of clean film at the top so product and oils stay out of the seal zone — debris in the seam is the #1 cause of a weak seal.

Step 4: Seal with even pressure

Lay the top of the bag flat in the sealer, press down firmly and evenly, and hold for the full cycle. Let the seam cool for a few seconds before moving the bag so it sets.

Step 5: Check the seal

Run a finger along the seam — it should be smooth and continuous with no gaps. Give it a gentle tug. A proper seal won’t peel.

Zipper or heat-seal?

Many of our bags include a resealable zipper for the customer—but you should still heat-seal above the zipper for tamper-evidence and a true smell-proof close. Bags marked heat-seal only don’t have a zipper and rely entirely on the seal. Each product page lists the closure type.

Common mistakes to avoid

• Product in the seam — wipe the top edge before sealing.
• Too much heat — burns through the film and weakens the seal.
• Rushing the cooldown — moving the bag too soon breaks a fresh seal.

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We sell empty packaging only. We do not sell cannabis, oil, or mushroom products.