Section 3 of 8
Barrier Properties
OTR and WVTR explained, test conditions, and typical reference values by structure type.
Packaging barrier is measured with two indicators. OTR (oxygen transmission rate) states how much oxygen passes through one square meter of material in 24 hours, expressed in cc/m²·24 h. WVTR (water vapor transmission rate) states how much moisture passes through in the same period, in g/m²·24 h. The lower the number, the higher the barrier.
Two values can only be compared if they were measured under the same conditions. The most common are OTR at 23 °C (73 °F) and 0 % relative humidity, and WVTR at 38 °C (100 °F) and 90 % RH, which simulate a hot, humid climate. A data sheet that does not state conditions cannot be compared with another. U.S. specifications often use cc/100 in²·24 h; multiply by 15.5 to convert to cc/m²·24 h.
What drives barrier: gauge (the thicker each layer, the lower the transmission, roughly in proportion), metallization (a vacuum-deposited aluminum layer on PET lowers OTR from over 100 to under 2), EVOH (very high oxygen barrier when dry, dependent on its thickness and on ambient humidity) and aluminum foil (nearly total barrier to light, oxygen and moisture, affected only by pinholes and creasing).
Actual values depend on the gauge of each layer, the laminating adhesive and the converting process: metallized films and foil lose barrier when creased or wrinkled, and EVOH loses barrier when exposed to humidity. That is why we do not assign a fixed barrier to a structure type: each project is specified in its technical data sheet, with the gauge of every layer, and verified against the certificate of analysis of each lot.
Barrier map
- PET 12 / PE80 – 120 · 3 – 6
- BOPP / BOPP · BOPP / VMBOPP800 – 1,500 · 30 – 100 with VMBOPP · 2 – 5 · 0.5 – 1.5 with VMBOPP
- PET / VMPET / PE0.5 – 2 · 0.5 – 2
- AlOx PET / BOPA / RCPP0.5 – 3 · 0.5 – 3
- PET / EVOH-PE1 – 5 · 3 – 6
- PET / AL / PE< 0.1 · < 0.1
- PET / AL / BOPA / RCPP (retort)< 0.1 · < 0.1
- MOPE / PE1,000 – 3,000 · 2 – 5
- MOPE / PE / EVOH-PE1 – 5 · 2 – 5
Logarithmic scale: each line is ten times the previous one. Typical reference values; your package's value is set in its technical sheet.
| Structure | OTR (cc/m²·24 h) | WVTR (g/m²·24 h) | Best for |
|---|---|---|---|
| PET 12 / PE | 80 – 120 | 3 – 6 | Dry, medium-turnover products with low oxygen sensitivity: granola, flours, snacks, treats. |
| BOPP / BOPP · BOPP / VMBOPP | 800 – 1,500 · 30 – 100 with VMBOPP | 2 – 5 · 0.5 – 1.5 with VMBOPP | Snacks, cookies and flow wrap; metallization adds moisture and light barrier for crunchy products. |
| PET / VMPET / PE | 0.5 – 2 | 0.5 – 2 | Coffee, powders, supplements and greasy snacks; high barrier with opacity. |
| AlOx PET / BOPA / RCPP | 0.5 – 3 | 0.5 – 3 | Transparent retort; barrier is verified after the sterilization process. |
| PET / EVOH-PE | 1 – 5 | 3 – 6 | Oxygen-sensitive products that require transparency; OTR rises with relative humidity. |
| PET / AL / PE | < 0.1 | < 0.1 | Powders, pharmaceuticals, coffee and long-shelf-life products that are not sterilized. |
| PET / AL / BOPA / RCPP (retort) | < 0.1 | < 0.1 | Long-shelf-life retort: ready meals and wet pet food; opaque structure. |
| MOPE / PE | 1,000 – 3,000 | 2 – 5 | Mono-material option for products that are not oxygen-sensitive; good moisture barrier. |
| MOPE / PE / EVOH-PE | 1 – 5 | 2 – 5 | Mono-material option with oxygen barrier: coffee, snacks, pet food. |
Typical industry reference values for common gauges (OTR at 23 °C / 0 % RH; WVTR at 38 °C / 90 % RH). They are not a specification from Aprint or from any manufacturer. Each structure is defined with the gauge of every layer in its technical data sheet and verified against the certificate of analysis of each lot; if your product depends on a specific barrier, the manufacturer's lab report is requested or a shelf-life test is run before production.
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