4-Side-Seal Bag
Also called: four-side-seal pouch, 4-side sealed packet
A 4-side-seal bag is a flat flexible pouch sealed on all four edges, with no recloseable opening. The product is loaded into a premade pouch during the packaging cycle, then the final edge is sealed — leaving the customer to tear or cut the pouch open. This construction delivers maximum seal integrity on every edge, making the format ideal for single-item products where barrier protection and tamper evidence matter more than resealability.
Unlike pillow bags (formed from a single web of film on a VFFS machine) or stand-up pouches (built around a bottom gusset), 4-side-seal pouches are produced from pre-cut films on horizontal form-fill-seal (HFFS) machinery. Two film plies are sealed along the perimeter simultaneously, trapping the product between them. The result is a perfectly flat, edge-sealed packet — the format used for everything from pharmaceutical pain-relief patches to rapid antigen test cards.
Lintyco manufactures a range of HFFS machines that produce 4-side-seal pouches, with speeds from 30 to 60 cycles per minute and pouch dimensions from 40×60 mm up to 100×150 mm. For higher output, multi-lane configurations multiply throughput without enlarging the individual pouch footprint.
Specifications
| Common materials | PET/PE, PET/AL/PE, paper/PE |
| Width range | 40–100 mm |
| Length range | 60–150 mm |
| Filling range | 5–50 g (single-item dependent) |
| Production method | Horizontal Form-Fill-Seal (HFFS), premade-pouch loaders |
Common applications
- ▸Pain relief patches & transdermal films
- ▸Face masks & skincare patches
- ▸Rapid diagnostic test cards
- ▸Single-dose pharmaceutical samples
- ▸Hydrogel patches & wound dressings
- ▸Small hardware (screws, batteries, SIM cards)
- ▸Collectible cards & trading cards
- ▸Tea bag overwraps & sample sachets
Pros & cons
Advantages
- ✓Maximum perimeter seal integrity — all 4 edges hermetically closed
- ✓Compact, single-item format minimizes material use
- ✓Tamper-evident — opening destroys the seal
- ✓Excellent for high-barrier structures (aluminum foil laminations)
- ✓Multi-lane HFFS scaling reaches 240+ units/min
Limitations
- ✗Low volumetric capacity — single-item only
- ✗Doesn't stand on shelf — needs secondary packaging
- ✗Not resealable — torn open, not re-closed
- ✗Premade-pouch format costs more per unit than VFFS-formed equivalents
Machines that make this bag
Find machines that make this bag
Tell us about your product and target speed — get matched to the right Lintyco HFFS machine in 60 seconds.
Find machines that make this bag →Get a quote for 4-side-seal bag machines
Tell us about your project — we'll reply within one business day with a configured quote.
Frequently asked questions
What is a 4-side-seal bag used for?
4-side-seal bags are used for single flat items that need maximum seal integrity on every edge — pain relief patches, face masks, rapid test cards, single-dose samples, and individual hardware pieces like screws or batteries.
What is the difference between 3-side-seal and 4-side-seal bags?
A 3-side-seal pouch is sealed on three edges with an opening on the fourth (usually top) for manual filling. A 4-side-seal pouch is sealed on all four edges — the product is loaded during manufacturing, then the fourth edge is sealed. 4-side-seal provides higher seal integrity but requires a different machine format (HFFS premade-pouch loaders rather than VFFS form-fill-seal).
What materials are used for 4-side-seal bags?
Typical structures are PET/PE for general items, PET/AL/PE for moisture- or light-sensitive products like pharmaceutical patches, and paper/PE for sustainable retail packaging. Barrier coatings and custom laminations are available for sensitive products.
Can Lintyco machines make custom 4-side-seal sizes?
Yes. Lintyco's BG130C HFFS and BG400 series handle 4-side-seal pouches from 40×60 mm up to 100×150 mm. For unusual sizes or barrier materials, contact our sales engineers with your spec — we'll configure tooling accordingly.