Capillary flow/Gas-liquid porometry is the most common method used for characterizing the pore size and distribution of samples. Bubble Point is based on the fact that test-liquid is held in the pores of the sample. Using capillary flow porometry, the gas pressure is used to force out the test-liquid through pores in a sample. The pressure at which pores empty is inversely proportional to the pore size, larger pores require lower pressure than do smaller pores. The resulting volumetric flow of gas through emptied pores is also measured. Pore Size is then calculated using the “Young-Laplace equation”.