My wife and I have moved into a property that has a straight, square-shaped, unlined masonry chimney. I need to clean it out before I install a stainless steel flue and a cast iron stove. What is the best way to give it a good thorough clean? I was thinking sooteater as I'd be able to use it for the steel flue in the future, but I'm not sure how well it works on masonry. Thanks.