Home > Listing of Enamels > Vintage EnamelClick Image To View Larger 644 Soft Fusing White (op) $8.00 Weight 1 oz ($8.00) 3070:=:8 Quantity: - + Qpaque, cataloged, Thompson Enamel for Copper, Silver, Gold, Iron and Steel. This enamel is "soft fusing" and should be fired at 1450 to 1550 degrees F. for approximately 1 to 3 minutes. All Enamel is pre-1990, 80 mesh and lead bearing.