TIL a coal forge can melt a wrought iron fence pretty quick if you're not careful
I was helping a friend at his place in Abilene last month, trying to straighten a bent gate hinge. He runs a coal forge and I usually stick to propane, so he showed me how to bank the fire and get a good heat. I figured wrought iron could take more heat than mild steel, but he said wrought actually gets soft and mushy around 2,200 F and can burn right up if you leave it in too long. Sure enough, a small piece of his fence picket turned into a sparkler in about 30 seconds while we were talking. Now I keep a closer eye on my temps and use a lower fire for anything old and hand forged.
Man, that sparkler moment is real. I had the same thing happen with an old wagon wheel rim I picked up at a flea market. Thought it was just rusty mild steel so I threw it in my propane forge at full blast. It started throwing sparks and a piece just dropped off. Turns out wrought iron has slag in it that makes it act way different at high heat. Now I keep those old pieces at a dull orange and work them slow, never let them get anywhere near yellow. You can usually tell wrought by the grain when you break it, it looks stringy like wood. Good call on the lower fire, that stuff is too hard to find to burn up.