Because of diffusion rates in organic materials, it may takes weeks or months to reach a moisture equilibrium.
On the other hand, diffusion rates get slower as the square root of the molar mass increases.
This numerical effect takes the form of an extra high diffusion rate.
Oxygen has a diffusion rate in air 10,000 times greater than in water.
Porosity occurs due to the difference in diffusion rate of the two species.
For air, typical diffusion rates are around 1 cm2/second.
Extraction using superheated water tends to be fast because diffusion rates increase with temperature.
Information about the diffusion rate and concentration can be obtained using one of the models described below.
The normal average diffusion rate is nine microns every 40 milliseconds.
The factors of the chosen temperature and applied pressure depend on the diffusion rate.