Non-toxic, stainless steel surface after fire surface will produce oxide skin (metal oxide), the surface of the black material may be the flame baking part of the incomplete combustion of carbon, the surface will be washed, after removing the oxide skin is still complete and good performance of stainless steel.

If the temperature is too high, exceeding the phase change point of the material, part of the material may produce phase change, affecting the performance, but will not produce toxic substances.