Nepheline Syenite 60
This recipe is very similar to the original; I just replaced the ball clay with kaolin. This seemed to make the glaze adhere more smoothly to the tile, and also gave it a pearlescent sheen. The high amount of magnesium in this glaze is what causes the crawling effect. It needs to be applied thickly in order to get a good amount of crawl – I applied it about 1/8 inch thick. It can give interesting results layered over slips and glazes, as long as the base glaze is fairly dry.