Permeation, in physics and engineering, is the penetration of a permeate (such as a liquid, gas, or vapor) through a solid, and is related to a material's intrinsic permeability. Permeability is tested by permeation measurement, for example by a minipermeameter. Description The permeate always migrates to the lower concentration in three steps: Sorption (at the interface): Gases, vapour or dissolved chemicals or suspended substances are adsorbed at the surface of the solid. Diffusion (throug… (More on Permeation)