cast iron cookware? how it looks black?

with regard to cast iron cookware, how do they look black? Was it painted black? or is this a property of cast iron that it becomes black by reacting with oxygen in the air?

Orc General wrote:
  Quoted Text Here  
s/air/hot air/
Same for steel.
Michael Dahms

There are some theories on seasoning the cast iron pan. Don't use mineral oil for seasoning, the theory seems to be to heat vegetable oil at low heat or cook some bacon in the new cast iron pan or cookware. It might not be necessary to bother seasoning the cast iron pan, but it's probably not a bad idea. Then, don't put the cast iron pan in the dishwasher, and go easy on the soap.
There are obviously many theories of correctly seasoning the cast iron cookware. By the same token, there can be only one strong, consistent, complete, and concrete theory.
Ross F.