Vacuum metallizing deposits a layer of aluminium — measured in nanometres, not microns — onto the surface of a base film under high vacuum. The result is a film that blocks moisture, oxygen and light, at a fraction of the thickness and cost of foil, with no meaningful change to the film’s mechanical handling. Metallized film is the same material you were already running, with the barrier problem solved.
OLUNRO metallizes PET, polypropylene, nylon and PE substrates in-house and supplies finished rolls to converters and to brands buying directly. The aluminium layer is deposited, not laminated, so the roll remains a single film — it prints, laminates and seals on the machinery you already have.
The four substrates we metallize
Metallized Polyester (VMPET) — the default choice for high-barrier laminates. Excellent moisture and oxygen barrier, high tensile strength, wide temperature range, and a clean surface for printing. Used where shelf-life is the governing constraint.
Metallized Polypropylene (VMCPP) — usually selected as the inner sealing web of a two-ply laminate. Good moisture barrier, low seal-initiation temperature, and economical.
Metallized Nylon (BOPA) — where puncture resistance and gas barrier both matter. Often specified for vacuum-packed and retort-adjacent applications where the pack must survive handling and abrasion without pinholing.
Metallized PE (VMPE) — the mono-material route to barrier. Metallized PE laminated with plain PE produces an all-polyolefin, recycling-compatible structure that replaces traditional three-layer builds. The ply design, the low-temperature limits and what the structure gives up are set out in our VMPE structure guide.
Water Vapour Transmission Rate: what metallizing actually buys you
(Values as published on our previous site, at 40 °C. PE-based figures are measured in-house under a stated condition and published separately — see the note below the table.)
| Material | Thickness (µm) | WVTR before metallizing g/(m²·24h) @ 40 °C |
WVTR after metallizing g/(m²·24h) @ 40 °C |
|---|---|---|---|
| PET | 12 | 40 – 45 | 0.3 – 0.5 |
| CPP | 25 | 10 – 15 | 1.0 – 1.5 |
| OPP | 20 | 5 – 7 | 0.8 – 1.2 |
| BOPA | 15 | 250 – 290 | 0.5 – 0.8 |
PE is not in this table, and that is deliberate. Polyethylene is the one substrate we metallize and measure in-house, so its figures come with a named gauge and a named test condition — you will find them on the VMPE page, not here. Putting an unqualified historical figure next to a measured one is how the wrong film gets specified.
Read the BOPA row carefully instead. A 15 µm nylon film transmits 250–290 g/m²·24h on its own — which is why bare nylon is a terrible moisture barrier and a good oxygen barrier. After metallizing it drops to 0.5–0.8. That is a reduction of roughly two and a half orders of magnitude in a single processing step, on the same film, with no added ply.
That is the whole commercial case for metallizing: you are buying a barrier upgrade, not a new material.
Note on the numbers. WVTR figures are substrate- and process-dependent. Use this table to understand the order-of-magnitude gain, then ask us for measured data on the exact structure you plan to run.
What actually decides the barrier: optical density
Ask three suppliers how thick their aluminium layer is and you will get three answers that cannot be compared. Nanometres of aluminium are difficult to measure directly on a finished roll, so the figure quoted is usually a machine set-point rather than a measurement of the product.
Optical density (OD) is the number that can be measured, and it is the one worth asking for. It is a spectrophotometric reading of how much light the aluminium layer stops. Higher OD means more aluminium deposited, and — up to a point — better barrier.
The relationship is not linear, which is the part buyers tend to miss. Barrier improves quickly as OD rises through the lower range, then flattens. Past that point you are adding aluminium for appearance rather than performance: the roll costs more and the shelf life does not move. Two films quoted at different OD values can perform identically in a pack, and two films at the same nominal OD from different lines may not.
That is why we quote an OD range alongside the substrate rather than a single layer thickness, and why the WVTR table above names the substrate and gauge for every row.
Adhesion is the failure nobody tests for
A metallized film can have excellent WVTR on the day it is made and poor adhesion a month later. The aluminium layer is thin enough that a weak bond does not show up as a visible defect. It shows up as barrier that quietly degrades after lamination, after printing, or after the roll has sat in a warm warehouse.
Three things control adhesion, and all three are process settings rather than material choices:
- Surface energy of the base. Aluminium has to wet the film. Base films are corona-treated before metallizing for exactly this reason, and that treatment decays with time — a roll metallized months after treatment does not behave like one metallized the same week.
- Vacuum and deposition rate. Faster deposition puts down more aluminium per second and builds a less ordered layer. It is a throughput-versus-anchorage trade, which is why two suppliers can hit the same OD and still behave differently downstream.
- What happens after metallizing. Lamination adhesive, ink solvents and storage humidity all act on the interface. A structure that tests well as a bare roll can lose adhesion once it is buried under print and adhesive.
The test that predicts field performance is a tape pull on the metallized surface after lamination, not before. If a supplier only reports adhesion on the bare roll, ask whether it was measured on the finished structure — that is the number that matters.
Metallized film or aluminium foil
This is the comparison buyers ask for most often. The honest answer is that the two are not competitors at the top end.
| Metallized film | Aluminium foil | |
|---|---|---|
| Barrier ceiling | High, but finite | Effectively absolute at 9 µm |
| Weight and cost | A fraction of foil | Highest of the barrier options |
| Flex and pinhole resistance | Good on a compliant base | Poor — pin-holes under repeated flexing |
| Appearance | Metallic, can be printed over | Opaque, no print-through |
| End of life | Same polymer family as the base | Multi-material in almost every structure |
Specify foil when the shelf life is measured in years, when the contents are genuinely oxygen-critical, or when the pack must be absolutely light-proof. Nine microns of aluminium transmits effectively nothing, and no metallized layer matches it.
Specify metallized when the shelf life is months rather than years, when the pack has to survive handling without pinholing, and when weight and cost are part of the brief. In most snack, confectionery and dry-goods formats, metallized now does the job foil used to do.
One case that catches people out: a foil laminate that passes on flat film can still fail at a gusset, because foil is the least forgiving of the barrier options under repeated flexing. If your current pack is a foil stand-up pouch and it is failing in the field, the answer is often a thicker metallized structure rather than more foil.
Where metallized films are specified
| Application | Typical structure | Why metallized |
|---|---|---|
| Snacks and savoury | VMPET / PE or VMCPP inner web | Moisture barrier at high speed |
| Coffee and dry powders | VMPET / PE | Aroma retention plus oxygen barrier |
| Confectionery | VMPET / VMCPP | Light and moisture barrier, print quality |
| Labels and surface decoration | VMPET | Metallized appearance without foil cost |
| Vacuum packs | VM-BOPA / PE | Abrasion and puncture resistance |
| Washing-machine and appliance labels | VMPET | Moisture and chemical resistance |
| Mono-material packs | VMPE / PE | Barrier plus recyclability |
Beyond packaging: transfer films
If you are not a flexible-packaging converter but still need a metallic finish, OLUNRO supplies metallic transfer films used in clothing and accessories, and in residential and commercial construction. Different converting route, same metallizing capability.
Why buyers shortlist OLUNRO
- Metallizing is in-house. Coating, lamination, slitting and bag-making are on the same site, so a structure change is a scheduling decision, not a new supplier.
- Four substrates from one source. PET, PP, nylon and PE — you do not have to qualify a different vendor per substrate.
- Trial rolls before commitment. Tell us the structure and the machine; we confirm the roll runs on your line.
Request a metallized film sample
Send the substrate, the target WVTR or shelf-life requirement, and your converting route. We will reply with the recommended substrate and optical density, a specification sheet, and a trial roll for your own line trials.
Contact: info@olunropack.com · +86 532 6776 6956