Over the years we have been lucky enough to find all of our cast iron pans in the garbage. Most of them looked pretty disgusting but underneath I knew they were perfect. Just this weekend we uncovered one on our third floor that came with the house and a much loved round griddle that has been up there in "storage" and forgotten about for many years (that one was a wedding gift).
The griddle was just a bit dusty but the skillet took some doing. Out came a copper scrubby, hot water, and the salt. The salt gives grit to help grind off the rust and grime. We rarely use soap on our cast irons. Usually we can just scrape it out, give it a quick rinse, and dry it on the burner. Here it is clean but not seasoned. Rub a little oil in there and heat it up. This weekend this pan saw fried eggs, a hot dog with fried onions, and an upside down apple cake.