It can't be overstated how much these coatings improve efficiency. I felt my forge was lagging and even though the inside still looked decent, I decided to give it a quick coat of ITC-100. It was fairly watered down, compared to how I would normally apply it to a non-coated forge. Maybe a 1/3 cup(after mixed) coated the entire inside of my 5x11 forge cavity. It was a very THIN touch up. The difference was VERY noticeable. I don't care how much the stuff costs ... I will continue to use it faithfully.