I love HCSM 1 + 2 from John Britt's Mastering Cone 6 but I need a white semi-matte glaze. Has anyone had any luck adding zircopax to these glazes to make them opaque and white? I did some searching and couldn't find anything. Would love some feedback from the hive mind before I jump (more like fall) headfirst into testing mode. Thanks bunches.