Thompson Enamel is the finest quality enamel available on the market and is carefully formulated in the United States and designed to perform consistently. 2680 Prussian Blue Thompson Transparent Enamel - 80 Mesh Medium Temperature Medium Expansion Enamel for Copper, Gold, Silver, Low Carbon Steel & Metal Clay. Normal firing temperature range is 1400-1500 degrees fahrenheit. Coefficient of Expansion Range is 258-360 cubic expansion. Made lead-free in the USA. Available in 1 Ounce Jar, 2 Ounce Jar, 8 Ounce Jar, & 5LB Container.