The inside, totally clouded glaze is G2926B. Outside is GA6-B Alberta Slip amber clear. The piece was fired at cone 6 using the PLC6DS schedule. The difference is amazing. Normally that inside glaze is crystal-clear on other bodies, but this black engobe is generating tiny gas bubbles at the exact wrong time during the firing and it is unable to pass them through the melt. Strangely, circumstances are implicating the black stain as the gas generator or catalyst. The outside glaze, although amber rather than completely transparent, has repeatedly demonstrated it abilities at melting to a transparent no matter what body it is on.
Clouding in Transparent Glazes
There a many factors to deal with in your ceramic process to achieve transparent glazes that actually fire to a crystal-clear glass