As you dip a pot into a bucket of glaze, a gradient of thickness results because of the speed and direction fo the dip. I love how some glazes like million $ yellow show this gradient. The extra drips of million $ yellow that fall down the sides also created brighter yellow marks.
On one side of this bowl, I dipped it partially in Shino glaze. The dark streak is a stripe of iron oxide painted over the glaze before firing.
Firing: Reduction high fire
Clay: Tuff Buff
Made with glazes at Echo Ceramics