Home > Listing of Enamels > Vintage Enamel > Thompson OpaquesClick Image To View Larger 478 Emerald (op) $6.00 Weight 1 oz ($6.00) 8 oz ($48.00) 16 oz ($96.00) 1892:=:6,1894:=:48,1895:=:96 Quantity: - + Opaque, cataloged, Thompson Enamel for Copper, Silver, Gold, Iron and Steel. This enamel is "medium fusing" and should be fired at 1450 to 1550 degrees F. for approximately 2 to 4 minutes. All Enamel is pre-1990, 80 mesh and lead bearing.