This is a wood ash glaze that has been used historically by Japanese and Korean potters. These artists traditionally used rice hull ashes and fired peices to temperatures upwards of 2500 degrees F. I have spent years adapting my Nuka glaze recipe to melt at a lower firing temperature, and to utilize local wood ashes. My goal is to achieve a fluid, rustic surface while maintaining whiteness. The glaze is very reactive to different pottery process. It varies in color from tan with brown speckles, to creamy white. The surface also varies from high gloss to soft, semi-matte.
I use 2 main colorants on my Nuka glazeware: iron and cobalt. The iron creates rust colors and yellows, and cobalt produces blues. I mix each colorant with water, then brush them on top of the glazed pottery. During the firing, these colorants drip down the pot and create fluidity and movement.