Cone 6: Blue Opal is a medium blue semi-transparent to fully opaque gloss glaze. Thinner applications create a transparent blue haze; thicker coatings produce an
opaque finish. Surface textures can cause the glaze to collect and produce streaks of greyish blue.
Cone 10: Becomes more transparent. Can produce red mottling in a heavy reduction.
*The first image is cone 6 and the second image is cone 10.
Tableware producers must test all finished ware to establish dinnerware status, due to possible variations in firing temperature and contamination.