- Cone 06–10 firing range - Matte finish - Three coats for opaque Amaco Lead-Free Velvet Underglazes can be used with or without glaze. When left unglazed, they will assume the rich textural appearance of velvet. When glazed with transparent matte glaze, they take on a soft, satin finish. Colors will intensify when covered with a clear transparent gloss glaze but will lose their matte surface quality. The underglazes fire true to color from the jar and can be easily applied to wet clay, greenware, or mature Cone 04 bisque (1971 F / 1077 C). To shade, tint, or customize the color of these underglazes, simply mix them with other colors. They may be brushed on mature fired bisque before applying a covering glaze. Fire to Cone 06-10 (1855°F–2381°F, 1013°C–1305°C). Some colors vary at higher temperatures. Please refer to the Resources tab of this page to download a PDF of Amaco's color variation chart for colors at Cone 5 and Cone 10.