|Monthly Tech-Tip |
Left: VC71 cone 6 silky matte glaze. Right: An adjustment that adds boron melter and SiO2/Al2O3 (which preserving their ratio). The dramatic improvement in melting was unexpected. Even though B has the same Si:Al ratio, it is completely glossy. Why? A (left) is simply not melting completely, that is why it is silky matte (not a true matte). Yet A feels like a good silky matte and is resistant to cutlery marking. Why? Feel alone can be misleading. Cutlery marking usually happens with matte glazes or heavily opacified whites, this is neither, it is an under-fired glossy glaze, fired just high enough not to mark.
Ceramic glazes that mark from cutlery are either not properly melted (lack flux), melted too much (lacking SiO2 and Al2O3), or have a micro-abrasive surface that abrades metal from cutlery.