There are two types of Crackle glazes – Watercolor and RC. These glaze colors flow and pool in the firing to create incomparable depth and beauty, particularly with relief tiles. Watercolor Glazes get their name from their deep, fluid clarity. This translucence emphasizes the variation in the tile’s surface and adds a shimmering quality. RC glazes are a little more opaque than Watercolors and have a slightly tighter crackle pattern.