Aluminium Foil vs Metallized Film vs EVOH: Barrier Level & Application Guide

Overview #

Barrier material selection is one of the most consequential decisions in flexible packaging — get it wrong and you’re looking at shelf-life failures, regulatory non-compliance, or a cost structure that kills your margin. This guide covers the three barrier systems we work with most on our lamination and extrusion lines: aluminium foil laminates, metallized film (typically VMPET or VMCPP), and EVOH-based coextruded structures. It’s most relevant to brands in food, nutraceuticals, personal care, and pharmaceutical packaging who are specifying a new pouch, sachet, or lidding film. The single most important thing to understand upfront: these three systems are not interchangeable — their oxygen transmission rates (OTR) differ by three to four orders of magnitude, and that gap drives every downstream decision about structure, sealing, and cost.

Barrier Performance: OTR, WVTR, and What the Numbers Actually Mean #

When a brand partner asks us “which barrier do I need?”, the first question we ask back is: what’s your target shelf life, and what’s your product’s critical oxygen and moisture sensitivity? Those two numbers determine everything.

Here’s how the three systems compare on the metrics that matter in production:

Aluminium foil at 9 µm gives us a true hermetic barrier — OTR below 0.01 cc/m²/day, WVTR below 0.01 g/m²/day. We specify 9 µm as our minimum foil gauge for retort and pharmaceutical applications; below that, pinhole density increases sharply during lamination tension and converting. For coffee, pet food, and medical device pouches requiring 18–24 month shelf life, foil is the only structure we recommend.

Metallized film is a cost-effective mid-barrier option. On our vacuum metallizing-sourced VMPET rolls, we require an optical density (OD) of ≥ 2.8 before accepting the reel into our lamination line — OD below 2.5 correlates with OTR above 3.0 cc/m²/day, which is inadequate for most dry food applications. We test every incoming metallized reel against ASTM F1249 for WVTR and ASTM D3985 for OTR before it enters our lamination schedule.

EVOH is the most nuanced of the three. Its barrier performance is excellent in dry conditions — down to 0.1 cc/m²/day OTR — but EVOH is hygroscopic. At 85% relative humidity, OTR can climb to 10–20 cc/m²/day depending on ethylene content. This is why we always sandwich EVOH between moisture-barrier layers (typically PA or PE) in our coextruded structures. For high-humidity environments like Southeast Asian markets, we recommend a minimum 80 µm PE outer layer on each side of the EVOH core.

Production Process Parameters: Lamination, Coextrusion, and Sealing #

Walking through our production floor, here’s what the process looks like for each barrier system and where the critical control points sit.

Aluminium Foil Lamination
We run foil lamination on our dry-bond laminator at a web tension of 80–120 N/m for the foil web — above 130 N/m we see micro-cracking at the foil layer that compromises barrier integrity. Adhesive coat weight is 3.0–4.5 g/m² (dry), and we cure at 45–50°C for 48 hours minimum before slitting. Bond strength must reach ≥ 1.8 N/15mm (T-peel, per ASTM F904) before the roll is released to converting. Any roll testing below 1.5 N/15mm is quarantined and re-evaluated.

Metallized Film Lamination
VMPET is more forgiving on tension — we run at 60–90 N/m — but the metallized surface is sensitive to corona treatment. We do not re-corona treat metallized film on our line; over-treatment strips the aluminium layer and destroys barrier. Incoming VMPET must have a surface dyne level of 38–42 mN/m as received. Adhesive coat weight for VMPET structures is 2.5–3.5 g/m² dry.

EVOH Coextrusion
Our blown film coextrusion line runs EVOH at a melt temperature of 190–210°C. EVOH degrades above 230°C and produces gels and black specks that create barrier weak points — we set a hard alarm at 225°C on the EVOH extruder zone. Screw speed for the EVOH layer is held at 15–25 RPM to maintain layer uniformity within ±10% of target thickness. We validate EVOH layer thickness by cross-section SEM on the first reel of every production run.

Compliance, Food Contact, and Certification Requirements #

All three barrier systems have distinct regulatory profiles that affect which applications they can serve.

Aluminium foil used in food-contact laminates must comply with EU Regulation 1935/2004 and, for US-bound product, FDA 21 CFR 177 (indirect food additives). The adhesive system is equally critical — we use solvent-free or low-migration adhesives that comply with EU 10/2011 for plastic materials in food contact. For pharmaceutical blister and sachet applications, we work to GMP standards and can supply full migration test documentation.

EVOH resins used in food packaging must also comply with EU 10/2011 and FDA 21 CFR 177.1950. We source EVOH from suppliers who provide full SML (specific migration limit) documentation. For nutraceutical and supplement brands, we recommend requesting our full material compliance dossier before finalising structure specification.

Metallized film does not contain aluminium in a form that raises the same migration concerns as foil, but the adhesive and substrate layers still require food-contact compliance documentation. We do not use PVDC-coated films in new structures due to chlorine content and end-of-life recyclability concerns — this aligns with the EU PPWR (Packaging and Packaging Waste Regulation) direction on halogenated materials.

For brands targeting FSC-certified or recyclable packaging claims: foil laminates are generally not recyclable in kerbside streams; EVOH-containing structures can qualify for recyclability under certain mono-material PE designs (PE/EVOH/PE); metallized film structures are similarly difficult to recycle unless designed as mono-material. We can advise on structure design for recyclability certification under How2Recycle or CEFLEX guidelines on request.

Specification Notes for Brand Partners #

When you brief us on a barrier packaging project, the most useful information you can give us upfront is: product type, target shelf life, distribution environment (temperature and humidity range), and whether the pack needs to be retortable, microwaveable, or recyclable. These four parameters alone determine whether we’re in foil, EVOH, or metallized film territory before we’ve looked at a single print file.

The most common brief mistake we see is brands specifying “high barrier” without a shelf-life target. “High barrier” means different things for a 6-month ambient snack versus a 24-month retort meal — and the cost difference between a VMPET structure and a foil retort laminate is significant. We’ll always push back on vague barrier specs and ask for the actual shelf-life requirement.

Our typical process: structure recommendation and indicative pricing in 3–5 working days from brief; physical barrier test samples (OTR/WVTR certified) in 10–15 working days; print and converting samples in 15–20 working days; production lead time 25–35 working days after structure and artwork approval.

Frequently Asked Questions #

Q1: What OTR level do I need for a 12-month ambient shelf life on a dry snack product?
A: For most dry snack applications at ambient conditions, a target OTR below 1.0 cc/m²/day is sufficient for 12-month shelf life. A metallized film structure with OD ≥ 2.8 typically achieves 0.5–2.0 cc/m²/day and is cost-effective for this application — foil is generally over-specified unless the product is highly oxygen-sensitive (e.g. roasted nuts or coffee).

Q2: What is your MOQ and lead time for a custom foil laminate pouch?
A: Our standard MOQ for foil laminate pouches is 50,000 units per SKU, though we can discuss lower volumes for new product launches. Production lead time after structure and artwork approval is 25–35 working days, which includes lamination, curing (minimum 48 hours at 45–50°C), slitting, and pouch converting.

Q3: Do your EVOH structures comply with EU food contact regulations?
A: Yes — the EVOH resins we specify comply with EU 10/2011 and FDA 21 CFR 177.1950. We can supply full SML migration documentation and material compliance dossiers for regulatory submissions. For pharmaceutical applications, we also work to GMP standards with full batch traceability.

Q4: Can you print directly on metallized film, and what finishing options are available?
A: We print on the outer PET layer of VMPET laminates using 8-colour rotogravure, which gives excellent metallic contrast effects. The incoming VMPET must have a surface dyne level of 38–42 mN/m for ink adhesion — we verify this on every incoming reel. Matte OPP lamination over the print layer is a popular option for premium brand aesthetics.

Q5: What’s the most common production defect in foil laminates and how do you prevent it?
A: Pinhole formation is the primary risk in foil lamination — we accept a maximum of 5 pinholes per m² on incoming foil reels, tested per ASTM F392. On our lamination line, we control foil web tension strictly between 80–120 N/m; exceeding 130 N/m causes micro-cracking that creates barrier weak points invisible to visual inspection but detectable by OTR testing. Every finished foil laminate roll is OTR-tested before release.

Planning a packaging project? Contact our team to request a complimentary specification review and sample quote.