Ewww.... never, never use a scratching pad on a precious old and honorable cast iron skillet. Just as one would never use a chemical, such as an oven cleaner on the pan. No... just place water in the pan and set in the oven or on the range top until the water boils for a short while... remove, empty water and wipe out with a paper towel. Then... place a couple of tablespoons of a good cooking oil or even non-Extra Virgin Olive oil in the pan and wipe it around thoroughly. It's set for storage and awaiting it's next delectable cooking chore...
That black color is to be cherished. One would not want one back to original color. We have pans and Dutch Ovens that are over 50 years old and the kids are already arguing over who'll get them...