Quick Answer: Permeability Cup is a test cup for measuring water-vapour transmission through films, coatings, membranes and sheet materials by the gravimetric cup method.
Last updated: October 2026
Key Features
Specimen sealed across the cup opening
Water or desiccant inside sets up a humidity difference
Mass change over time shows vapour transmission
Compares moisture-barrier performance of different materials
About This Product
A conditioned specimen is laid across the cup opening without wrinkles or gaps and sealed and clamped in place, with the specified water or desiccant inside. The assembled cup is weighed, held under the required conditions and reweighed over time, and the change in mass shows how readily water vapour passes through the material. It supports material science, polymer and chemical engineering teaching on permeability and permeance.
Frequently Asked Questions
Q1. How does the gravimetric cup method work? A humidity difference is kept across the sealed specimen using water or a desiccant in the cup. Changes in the total mass of the cup over time show how much water vapour has passed through the specimen.
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