I did a test of the brick porosity of one of my firebricks yesterday. The brick was 12"x 9 1/4" x 3" and weighed 9.25Kg dry. Soaked for 24Hrs it weighed 11.5 Kg which is approx.20% I did not remove moisture from the dry brick first and my old spring bathroom scales are not too accurate but it indicates that the brick has taken on a lot of water. This indicates that the brick is very porous and not very vitrified. This quality is desirable to make the brick highly refractory but undesirable in that it will absorb water easily and hold a large quantity. I have read that it is the moist heat that is the WFO's secret, so perhaps the porosity of the bricks is an important factor in the WFO's success in cooking superiority.