Using the same rheometer and geometry setup as described above, the rheometer was run under controlled stress mode to determine yield stress. Sample strain was monitored as the stress applied to each sample gradually increased in 0.1 Pa increments. Each stress was applied for 30 s and then increased to the next stress level to determine when sample flow was initiated (seen as a continuous increase in sample strain). This procedure allowed for more sensitive yield stress determination with 0.1 Pa being the experimentally determined yield stress sensitivity limit. Note, any yield stress below 0.1 Pa was not recorded, but yield stresses below 0.1 Pa may still exist in these samples.