Sometimes, it pays to follow directions. I fell in love with this glaze, a variation on Richard Aerni's recipe from John Britt's The Complete Guide to High Fire Glazes. My first few experiments with the glaze were successful, but lacked visual interest that's the hallmark of wood ash glazes. Then I read Richard's website, where he describes his glazing process. Because he single-fires, he sprays his glazes. And he gets such depth by applying alternating layers of glaze and slip. So I tried it his way on this mug, and voilà!