Choosing a Pouch Film: Clear, Metallised, Foil, Kraft or Mono-Material

Printing decides how a pouch looks, but the film decides how well it protects what is inside. Two doypacks of the same size, one a clear two-layer laminate and the other a three-layer foil structure, are completely different packs in terms of shelf life, appearance and cost. This guide walks through which structure suits which product, what the barrier terms actually mean and the questions worth asking before you decide.

What a film structure is and why it has layers

Flexible packaging films are rarely a single material. Most are several layers bonded together, a process called lamination, and the result is known as a multi-layer structure. Each layer earns its place:

• The outer layer, usually PET or BOPP, carries the print and resists scuffs and heat. This is where a matte or gloss finish comes from.
• The barrier layer, such as metallised film, aluminium foil or EVOH, keeps out oxygen, moisture and light.
• The inner layer, usually PE or CPP, touches the product and melts to form the heat seals.

Thicknesses are given in microns. A structure written as “12 PET + 12 MET PET + 80 PE” has a 12-micron PET outer, a 12-micron metallised PET middle and an 80-micron PE sealing layer.

Barrier, OTR and WVTR in plain terms

Barrier describes how well a film resists gases and moisture getting through it. Two numbers do most of the work:

• OTR, oxygen transmission rate: how much oxygen passes through a set area of film in a day. It drives rancidity in oily products and aroma loss in coffee.
• WVTR, water vapour transmission rate: how much moisture passes through. It matters most for crisps, crackers, powders and coffee, which all go stale or clump when they pick up water.

For both, a lower number means better protection. Light is a separate question. Clear films let it through, metallised films stop most of it and foil stops practically all of it. For light-sensitive products such as coffee, oily nuts and some spices, that difference shows up in colour and taste.

The main material families

Clear laminates. Two-layer films such as PET + PE or BOPP + CPP show off the product and keep costs down. They handle moisture well but offer limited protection from oxygen and light, which makes them a good fit for robust dry goods: rice, pulses, pasta, confectionery. A matte outer version gives a calmer look while still showing the contents; see matte BOPP.

Metallised laminates. A very thin metal coating on the middle layer blocks most light and oxygen, with a bright finish at a sensible cost. This is the go-to mid-to-high barrier option for coffee, nuts and granola. The metallised film entry has more detail.

Foil laminates. A thin layer of aluminium foil gives the strongest protection against moisture, oxygen and light. It suits coffee meant for long shelf lives, sensitive powders and some liquids. The downsides: the product is hidden, the cost is higher and recycling is difficult.

Kraft laminates. Kraft paper on the outside with a metallised or foil barrier underneath. You get a natural, crafted look that works well for coffee and nuts. The paper itself provides no barrier; the inner layers do the protecting. Print on paper also comes out slightly softer and warmer than on film.

Mono-material recyclable films. Every layer comes from one polymer family, usually polyethylene, so the pack is designed for the PE recycling stream. A standard mono-material PE film offers moderate protection, and adding a thin EVOH layer lifts the oxygen barrier considerably.

A decision table by product

Use this as a starting point for common products. Shelf-life figures show what a structure can typically support; the real figure depends on the product, filling conditions and storage.

Five questions to settle before you choose

• How long will it sit on the shelf? If your target shelf life is short, paying for a high barrier is wasted money. If it is long, a cheap film ends up costing more through returns and complaints.
• Is the product light-sensitive? Then move from clear to metallised or foil, and if you want to show the product, keep the window small.
• Is it oily, or does it absorb moisture? Oily products are mostly an OTR question; moisture-hungry ones are a WVTR question.
• Do shoppers need to see it? Visibility sells, but it costs protection. A window pouch is often the sensible compromise.
• Is recyclability a requirement? If a retailer or market expects it, start with mono-material options. Foil and mixed-polymer laminates will not get you there.

Food contact and real-world testing

Any structure that touches food needs an inner layer, ink and adhesive system that meets food-contact requirements. Acidic, alcoholic or very oily products also need the inner layer checked for compatibility with those contents.

Barrier data points you in the right direction, but nothing beats a test with your own product. For anything critical, fill sample pouches in the structure you have in mind and store them under realistic conditions for a few weeks, watching colour, aroma, crunch and moisture.

How material affects printing and cost

Your film choice also narrows your print options. Not every structure runs on every press; kraft-faced films, for instance, are usually printed flexo. Higher barrier means a higher cost per square metre, although that gap is usually small next to the cost of spoiled product.

You can compare how different structures change the cost for your size and quantity in the price calculator. If you are unsure which film your product needs, get in touch and we will work it out with you.