Spectrum Underglazes

All of our underglaze colors are lead-free, A/P non-toxic and dinnerware safe when covered with a dinnerware safe clear glaze. We offer a full palette of rich, vibrant colors that are opaque with 3 coats, semi-opaque with 2 coats and semi-transparent with 1 coat. They are compatible for use under most clear glazes. Unlike many other brands of underglaze we use a frit base rather than a slip (clay) base for our underglazes. The advantages to the user are that our underglazes can be applied on greenware or bisque and they can be used with or without a clear glaze covering. When used without a clear glaze cover they have a matte velvet like surface. However, when used without a clear glaze cover they are not considered dinnerware safe because the rough surface can be difficult to clean and can encourage bacteria growth. Our color chart shows the unglazed color in the right (lower) half of the tile and the color when covered by a clear gloss glaze in the left (raised) half of the tile. The color chart samples were fired at cone 05. Our underglazes generally have good temperature stability up to cone 6 and for many colors to cone 10. When fired hotter than cone 04 you may get small color variations from those shown on our charts, so please test them for your application. Some of our underglaze colors will start to look glossy without any clear glaze cover at cone 5. These softer colors are 507, 530, 537, 544, 552, 560, 567 and 568. Our underglazes can be intermixed to create your own colors. However, we recommend not mixing 561, 562, 563, 567, 568, 569 with any of the other colors. These colors are based on cadmium encapsulated stains that do not mix well with other ceramic stain colors.