Start with the product
The product dictates the packaging. Coffee releases carbon dioxide for days after roasting, so a one-way degassing valve is common. Snacks need protection from moisture and oxygen to stay crisp. Pet food is dense and often sharp-edged, so the film must resist puncturing. Tea is sensitive to odour and moisture. Before choosing a structure, list what the product needs: oxygen barrier, moisture barrier, light block, grease resistance, or all of them.
Also consider the fill method. Vertical form-fill-seal (VFFS) uses rollstock film and is common for snacks and coffee. Pre-made pouches suit lower volumes or products that need a shaped bag. Spout pouches work for liquids and semi-liquids. The fill method affects the film's slip, seal strength and stiffness.
Choose the right material
Most flexible packaging is a laminate. Each layer has a job. PET gives strength and printability. Aluminium foil (AL) provides an absolute barrier to light, oxygen and moisture. PE is the seal layer. NY (nylon) adds puncture and flex resistance. A common coffee structure is PET/AL/PE. For snacks, PET/NY/PE offers good puncture resistance without foil. Kraft paper laminates give a natural look but need an inner barrier layer for shelf life.
Recyclable mono-material options include PE and PP. They work for many dry products but may not match foil's barrier. Compostable options include PLA and PBS, which require industrial composting. Degradable options exist but check regional rules. The right choice balances protection, shelf life, cost and end-of-life.
Barrier and shelf life
Barrier is measured by oxygen transmission rate (OTR) and water vapour transmission rate (WVTR). Lower numbers mean better protection. Foil laminates have near-zero OTR and WVTR. Metallised PET (MET-PET) is a mid-range option. Mono-material PE has higher transmission rates. If the product is sensitive, ask for barrier data before committing.
Shelf life also depends on headspace, residual oxygen and storage temperature. A high-barrier film cannot fix a bad seal or too much air in the bag. For coffee, the valve releases CO2 but does not let oxygen in. For snacks, nitrogen flushing removes oxygen. For pet food, the main risks are moisture and fat oxidation. Test the full package, not just the film.
Filling and sealing
Filling equipment sets limits on film. VFFS machines need film with consistent coefficient of friction (COF) and seal strength. Pre-made pouches need a fill-seal machine. Spout pouches need a spout inserter. The seal layer must match the machine's temperature, pressure and dwell time. If the seal is too weak, leaks occur. If too strong, the film may stretch or burn.
Common add-ons affect filling and sealing. A zipper lets consumers reseal the bag but can slow the fill line. A tear notch helps opening but must be placed precisely. A window shows the product but reduces barrier. A hang hole suits retail display. A carry handle helps large formats. Each add-on adds cost and may change the film structure.
What drives cost
Several factors drive the unit price of flexible packaging. Structure and material: foil and nylon cost more than PE. Print method: rotogravure has high setup costs but low running costs at volume. Digital printing has low setup and suits short runs. Order quantity: larger runs spread setup costs. Add-ons: valves, zippers, spouts and handles add material and process steps. Size and shape: larger bags use more film. Freight and lead time also affect total cost.
MOQ depends on print method. Digital printing starts from 100 pcs for pouches and 10 kg for film. Rotogravure starts from 10,000 pcs or 200 kg. Lead time is 10-15 working days for digital after artwork approval, and 20-25 working days for rotogravure. Plan artwork and approvals early to avoid delays.
Sustainability and common mistakes
Sustainability rules vary by market. The EU has strict packaging and waste regulations. Some regions require recyclable or compostable packaging. Mono-material PE and PP are recyclable where facilities exist. PLA and PBS are compostable in industrial conditions. Degradable plastics are banned in some places. Always check local rules before choosing a material. Also consider the full life cycle, not just the label.
Common mistakes include: - Choosing a film without checking barrier data. - Ignoring the fill line's COF and seal requirements. - Adding a zipper or valve without testing the full package. - Ordering too little for a rotogravure run. - Forgetting artwork approval time. - Assuming a stock pouch fits a custom product. Test the package with the real product and the real machine before scaling up.