Cone 6 oxidation: Midnight Rain is a blue-green breaking gloss glaze that contains a black crystal. As the crystal melts and moves, a black oil-like streak is created in the glaze.
Cone 10 reduction (second image): Crystals melt and integrate into base glaze, darkening the color. Increased movement.
TIP: SW-100 Blue Surf is the base glaze. For a lighter crystal effect, you may try applying two coats of SW-100 Blue Surf with a third coat of SW-115 Midnight Rain.