The most common reason your skillet could be sticky is that you've used too much oil when seasoning it. To get rid of the gunk, use a scouring pad or coarse sea salt to scrub your pan and rinse it with water. If you have a thick build-up, or it's more persistent, pop your skillet in the oven for an hour at 350 degrees Fahrenheit. Wipe it out and re-season.