What are the Heat Tint Colors for Stainless Steel and When Do They Form?
When stainless steel is exposed to an air atmosphere, or a high dew point moisture laden atmosphere during heating or cooling, its surface changes color, that is, a thin oxide layer forms on the surface. This heat tint color (aka temper color) is caused by a progressive thickening of the surface oxide layer. As most of us know, an invisible (aka passive) layer, occurs naturally on stainless steels. It is extremely thin, typically in the order of 1 to 3 nanometers (3.93 x 10-8 to 1.18 x 10-7 inches) thick.