The picture for this item is just one example of the Raku Crackle White glaze. This is technically a clear glaze (there's no opacifier in the recipe), but everyone refers to it as Crackle White. Feel free to experiment with underglazes, stains, and even non-raku glazes underneath this Crackle White glaze. You can also add stains or chemical colorants (like cobalt oxide, copper carbonate, etc) for dramatic results. You might really enjoy the experimentation!
Mixing instructions: mix with water at a 1:1 ratio (pint of water to a pound of glaze) and apply two coats.