Unlocking Reliable WVTR Testing for Sustainable Packaging

Sustainable packaging materials — molded fiber, coated paper, bio-based films — are hard to test for moisture barrier performance with existing WVTR methods. AQUALAB's Zachary Cartwright and lab director Mary Galloway explain why: outsourced testing is slow and expensive, standalone analyzers aren't built for eco-friendly substrates, and manual ASTM E96 cup tests suffer from edge diffusion that makes porous, fiber-based materials read artificially low on WVTR — creating a false sense of packaging protection. Galloway introduces AQUALAB's new WVTR testing cell (patent pending), which seals the sample edge to eliminate that vapor leak and slots directly into the existing AQUALAB VSA, so one instrument now runs both moisture sorption isotherms and WVTR analysis. The cell targets mid-range fiber and film packaging (roughly 4–10 g/m²/day), needs no carrier gas, and tests typically complete in one to two days. The session closes with a preview of the upcoming Moisture Analysis Toolkit 3.0 software, which automates WVTR calculation and merges it with isotherm data for a full moisture barrier profile.