My girlfriend bought a cafe and they had a cast iron waffle iron that had, in some places, 5mm of grime built up over 2 years, never once been cleaned. Even the hinges were full of old crusted on batter and grease.

I spent hours with a grill scraper scraping every individual pin.

I have gotten to or past the seasoning in many places except in between all of the pins is hell to try to scrape the old baked on grease away. I have tried sodium carbonate soaks, a wire brush and a wire brush on a drill, a few different scraping tools, and I have only gotten about half out of those grooves. Miles better than before, but still not perfect enough to season and put back in the cafe.