Pro tip: I stopped eyeballing my forge temp and stuck a $12 magnet on the anvil
Honestly for my first two years I just watched the color and guessed. Then a guy at the Columbus spring hammer-in showed me the magnet trick and it changed how I run the fire. Now I keep a small magnet on a wire by the anvil and pull it off the steel when it stops sticking, which is right around 1425 F for most of my work. How do you all judge your heat, color or a tool?