Abstract: A frit of the following approximate analysis in percent by weight______________________________________ Alumina Al.sub.2 O.sub.3 8 to 12 Boron trioxide B.sub.2 O.sub.3 40 to 60 Sodium monoxide Na.sub.2 O 6 to 14 Lead monoxide PbO 0 to 7 Calcium oxide CaO 6 to 11 Barium oxide BaO 7 to 12 Manganese oxide MnO 2 to 6 Cobalt oxide CoO 0 to 2 Silica SiO.sub.2 Under 1 ______________________________________when admixed with other materials, in parts by weight as follows ______________________________________ frit 30 to 60 aluminum powder 5 to 60 silicon powder 0 to 8 chromium trioxide 0 to 10 zirconium silicate 0 to 10 copper oxide 0 to 3 bentonite 0.5 to 3 water 70 to 80 ______________________________________applied to an iron-based part, and then fired at 800.degree. to 950.degree. C. results in a heat-resistant weldable enamel. It is especially suited for automobile engine mufflers.