Clock Fixer

Ok, I'm not a blacksmith, but in the course of clock repair and restoration, I sometimes come across clocks that had faux bronze finishes applied. I just found a new recipe I'd like to try, but I need to know the correct temperature to create the finish. In the recipe, the oven should be hot enough to turn a raw cast iron piece straw yellow to light blue. Can anyone tell me what degree of heat will do this? Thanks, Chris.