Can I put White Earthenware in the same bisque fire as Buff Grogged Clay? As they are within the same temperatures to be fired at. The same with Terracotta Smooth? Buff Grogged - 1120-1280 White Earthenware - 1060-1160 Terracotta Smooth - 1020 - 1160 Also, I am testing a glaze idea of drawing onto glaze with a normal led pencil and another test piece with compressed drawing charcoal on it. Has anyone tried this and can tell me that it they are safe ingredients to go in a glaze firing/the kiln itself? Thanks.