TINNING BATH AND TINNING METHOD

PROBLEM TO BE SOLVED: To prepare a low-pollution and low-cost tinning bath by which, even if a steel strip is continuously tinned at a high current density, a tin plating free of burning and excellent in appearance is obtained and the generation of sludge is remarkably reduced even in the continuous operation. SOLUTION: Ferrous ion in an amount of 0.1-20g/l or 0.1-5g/l tinning bath- soluble amino compd. or 0.1-20g/l ferrous ion and 0.1-5g/l tinning bath-soluble amino compd. are incorporated into a tinning bath consisting of 10-50g/l sulfuric acid, 20-100g/l stannous ion and 1-10g/l ethoxy-α-naphtholsulfonic acid and/or ethoxy-α-naphthol to prepare a tinning bath capable of high-current density plating. Further, a steel strip is continuously tinned at >=30A/dm current density by the use of a tinning bath kept at 30-60 deg.C.