Before you approve artwork on a pouch, pin down two numbers: the oxygen transmission rate (OTR) and the water vapor transmission rate (WVTR). OTR tells you how fast oxygen moves into the pack and oxidises your product; WVTR tells you how fast moisture moves in or out. Together they decide whether your coffee still smells fresh at month 10 or tastes stale at month 6.
The short answer: work out which metric dominates for your product, set a target in the right units — cc/m²/day for OTR, g/m²/day for WVTR — and only compare suppliers under the same temperature and humidity. Then ask for the test report on your exact structure, not a generic "high barrier" promise.
What OTR and WVTR actually measure
Oxygen Transmission Rate (OTR)
OTR is how much oxygen passes through one square metre of film in 24 hours, reported in cc/m²/day (sometimes cm³/(m²·day)). It is measured with a coulometric sensor under ASTM D3985, typically at 23 °C and 0% relative humidity. A lower number means a stronger oxygen barrier.
Oxygen is what makes fats and oils go rancid, breaks down delicate actives and flattens roasted-coffee aroma. If your product oxidises, OTR is the number you care about most.
Water Vapor Transmission Rate (WVTR)
WVTR — also written MVTR — is how much water vapor passes through one square metre in 24 hours, in g/m²/day. Modern high-barrier films are usually tested with an infrared sensor under ASTM F1249, which is more sensitive and repeatable than the older gravimetric ASTM E96 method.
Moisture is the quieter failure: powders clump, gummies stick together, probiotics lose viability and crisp dry foods go soft. If your product is moisture-sensitive, WVTR is the metric to lead with.
Why the test conditions change the number
OTR and WVTR are not single fixed values — they move with temperature and humidity. A result at 23 °C and 0% RH (dry) is a different test from 38 °C and 90% RH (humid, ASTM F1927). Some barrier layers, especially EVOH, lose a meaningful share of their oxygen barrier at high humidity.
That is why a "barrier" figure without its test conditions is not comparable. Always confirm the standard, temperature, relative humidity, and whether the value is for the raw film or the finished, sealed pouch.
Which metric matters for your product
| Product | What degrades | Metric to lead with | The failure you are preventing |
|---|---|---|---|
| Roasted coffee | Lipid oxidation, volatile/aroma loss | OTR (plus a degassing valve) | Stale, flat aroma and rancid oils |
| Supplements (gummies, probiotics, softgels, powders) | Moisture pickup and oxidation of oils | WVTR for dry/powder forms; OTR for oil-based softgels | Clumped gummies, lost probiotic CFU, oxidised oils |
| Dry pet food and treats | Rancidity of fats, moisture pickup | Both — OTR for fat stability, WVTR for crispness | Rancid kibble, soft texture |
| Skincare (serums, creams, refills) | Oxidation of actives, fragrance/volatile loss | OTR for actives, WVTR to hold water content | Discoloured actives, weak scent, dried-out formula |
Roasted coffee is the most oxygen-hungry case on this list: oxygen drives the lipid oxidation and aroma loss, which is why most specialty roasters also fit a one-way degassing valve to vent CO₂. Many specialty specs land at an OTR around or below 1 cc/m²/day for a 12-month shelf life — confirm your own target with a shelf-life study rather than copying a number.
Match the structure to the threat
Pick the format from the failure you are preventing, not the other way round:
- Coffee and tea → side-gusset bags or flat-bottom pouches, with a one-way valve for fresh-roasted product.
- Supplements and powders → standup zipper pouches with a resealable closure.
- Skincare refills and liquids → spout pouches or a standup refill format.
How to read a supplier's barrier spec without being misled
- Ask for the finished-structure value, not the raw film. Lamination, sealant layer and coating change the result.
- Confirm the standard and conditions: ASTM D3985 for OTR, ASTM F1249 or ISO 15106 for WVTR, and the temperature/RH.
- Ask whether the number is for film or the formed, sealed pouch. Zippers, spouts and seals are the usual weak points.
- Treat "high barrier" or "excellent oxygen protection" with no number and no method as a request for the report.
What to put in your RFQ
Send us the four things that actually determine the barrier, and we will propose a structure:
- Product and fill: roasted coffee, oil-based softgel, water-based serum, dry kibble.
- Target shelf life and shelf conditions: ambient, refrigerated, or humid (bathroom) storage.
- Required OTR (cc/m²/day) and WVTR (g/m²/day) — or ask us to propose targets from your shelf-life goal.
- Constraints: food-contact market, hot-fill or retort, and any mono-material or recyclability goal.
How Foldveil confirms barrier
We do not publish a single "standard" OTR or WVTR, because the real number depends on the exact film structure, gauge and seal for your order. Barrier values are confirmed the same way certifications are: verified for the selected factory, material structure and production run, with the applicable test report shared with the quote where applicable.
One honest trade-off to plan for: stronger barriers often come from metallised or EVOH layers, which can pull against a mono-material or recyclability target. There are recyclable high-barrier routes — the structure matrix in our mono-material mailer comparison explains the PE/PE, PE/EVOH, OPP/CPP and BOPP/EVOH options — but you will usually be choosing a point on that curve, not getting everything at once.
Start with two numbers, not a stack of samples
You do not need a full discovery call to move forward. Send us your product, format and target shelf life through the RFQ form, and we will come back with a proposed structure and the barrier report scope — so you are comparing real numbers, not adjectives.
For more on the format decisions, see our guides to side-gusset vs flat-bottom coffee bags and the stand-up pouch spec sheet.
Sources and further reading
- ASTM D3985-24, Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor — ASTM
- AMETEK MOCON, "ASTM E96 vs F1249: Which provides more accurate test results?" — white paper
- Packaging World, "Oxygen Transmission Rate and Barrier Flexible Packaging" — Packaging World
- "Effect of Monomaterial and Multimaterial Packaging on the Stability of Bioactive Compounds and Lipid Oxidation in Roasted Arabica Coffee," Processes (2026) — DOI 10.3390/pr14111740