Cast iron can be pretty tricky to clean because you have to be careful not to remove your pan’s seasoning. Using a scouring pad or steel wool will strip this coating any time it is used.
This can create quite the dilemma whenever dealing with baked-on food. However, using salt to scrub away scum is a great alternative and it won’t strip away any of the seasoning. So, now you can start using your cast iron skillet again without dreading the clean-up.
SOURCE: bigchill.com