Custom Heavy Duty Mylar Bags

Choosing a Bag Style for Custom Heavy Duty Mylar Bags

A flat-bottom or box-bottom bag stands upright on its own and holds its shape when full, which makes it the favourite for retail bulk products. A stand-up pouch with a gusseted base is the next most popular and holds a good weight while staying compact. For pure storage, a simple three-side-seal flat bag is the most economical and packs efficiently into buckets or crates.

Closures depend on how the bag will be used. For sealed long-term storage, the bag is usually heat-sealed across the top after filling and opened only when needed. For goods the customer will dip into regularly, a heavy-duty zip makes resealing easy. Many brands use both: a heat seal above the zip for tamper evidence, with the zip for everyday use once opened.

Tear notches let the customer open a heat-sealed bag cleanly by hand. On thicker films a notch makes a real difference, because heavy laminate is hard to tear without one.

Printing on Thick Foil Laminates

Heavy duty mylar can be printed in full colour, with the artwork reverse-printed onto the inner face of the outer film so it sits protected under the surface. That keeps it from scuffing when bags rub together in storage or transit. A matte outer film gives a modern look and hides fingerprints; gloss makes colours pop on a shelf.

Metallic foil showing through unprinted areas is a strong design feature. Leaving the logo or a band of the bag unprinted lets the silver or gold foil shine through, which reads as premium without any special finishing. A clear window is possible on some constructions, but it reduces the barrier, so for long-term storage we usually advise against it.

Leave room for the details customers need: contents, weight, a packing date panel and any storage guidance. For bulk storage bags, a large white write-on panel is handy for adding dates by hand. p2 A window version for lighter contents is on our mylar bags with a window page.

Sizing by Weight and Volume

Heavy duty bags are usually chosen by fill weight rather than by dimensions alone. A bag that holds a kilogram of rice will hold far less by weight of puffed cereal, so size from the actual product. Fill a sample bag or a container of known volume and note the weight, then we can match a bag that leaves enough headroom above the product for a clean seal.

Leave at least 30 to 40 mm of empty film above the fill line for heat sealing, and more if there is a zip. Overfilled bags are hard to seal properly and are the most common cause of failed long-term storage.

For a retail range, it helps to keep the bag width the same across two or three fill weights and change only the height. Shelves look more orderly and one artwork layout adapts easily. p2 Flour and grain sellers can see worked sizes on our flour mylar bags page.

Filling and Sealing Tips

Wipe the inside of the sealing area clean before heat sealing; dust from flour or grain trapped in the seal can create a weak channel. Use an impulse or band sealer set for thicker films, as a light domestic sealer may not fuse heavy laminate fully. Check the seal by gently squeezing the bag after it cools.

If you add oxygen absorbers, seal promptly after adding them. Food-contact grade inner films are available on request, and we confirm the laminate on your quote.

Store filled bags somewhere cool, dark and dry, off concrete floors, and avoid stacking heavy bags directly on top of sharp-edged boxes. If bags are going into buckets or crates, smooth the air out gently before sealing so the bag sits flat and the film is not stretched over corners. Label each bag with its contents and packing date as you go; it saves guesswork months later. p2 Vacuum sealing for very long storage is covered on our vacuum-sealed mylar bags page.

Fill a Jug to Your Target Weight and Read the Volume

Heavy duty bags are ordered by weight and filled by volume, and the two do not line up: a kilogram of rolled oats takes nearly twice the room of a kilogram of rice. Pour your product into a measuring jug to the weight you want per bag, read the volume, and send that with the product name. We match a bag that leaves 30 to 40 mm of clean film above the fill for the seal, and more if you want a zip.

Tell us the sealer you use, because a light domestic sealer will not fuse a thick laminate, and say if the bags go into buckets, which favours a flat bag over a gusseted one. The custom quote arrives by email within one working day, from £0.25 for the smaller plain sizes, with the minimum set per job.

The free proof shows the artwork with the seal and zip areas marked and any write-on date panel in place. Production takes 4 to 7 working days after approval and the bags reach UK mainland addresses by free tracked delivery. Bulk food sellers who also sell by the cup often add small mylar bags for samples in the same print.