Once initiated from a flaw-like inhomogeneity perpendicular to the greatest compression, the lateral propagation of a pressure solution is dictated by the stress concentration at its tips. In fact, according to the anti-crack model of pressure solution, the intensity of the stress concentration for a closing mode structure is the same as that of an opening mode structure but the signs are opposite (Fletcher and Pollard, 1981; Sternlof et al., 2005). However, Katsman et al. (2006) calculated a lower stress concentration factor for a Localized Volume Reduction Structure. This was later verified by Zhou and Aydin (2010). See some model results provided under 'Mechanisms and Mechanics of Pressure Solution Seams' supporting the tip-stress derived propagation scenario. However, a critical stress intensity factor for the propagation criterion for the lateral propagation of pressure solution seams is not yet known.