Nisshin Steel Co., Ltd.

Hidehiro Shibata

Kiyoshi Takatsu

Takeshi Takeuchi

Hisao Takamura

This invention relates to a method for coloring stainless steel by controlling the potential difference between the surface of the stainless steel being colored and a reference electrode in a coloring liquor, characterized by differentiating a potential-time curve showing the variation with time of the potential difference between the surface of the stainless steel and the reference electrode by time to prepare the differentiation curve thereof and removing the stainless steel from the coloring liquor when the potential difference has changed from the coloring starting point that is the inflexion point on this differentiation curve, at which the variation amount of the potential per unit time changes from a falling tendency to a rising tendency, by a predetermined amount associated with the desired color.

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Ichikawa, Japan

Hidehiro Shibata