I was browsing a website that restores old garden machinery and they provided a carbureter cleaning service by acid cleaning. Looking at the results of the pictures the finish was as new, like it was a fresh casting made at the factory. I have noticed in the past that Mazak 2" Mortar fins etc can tarnish to a dull grey colour over the years. I was wondering what type of acid cleaning chemical is used. It did have a try at cleaning some cast aluminuim and Mazak myself using some Cilitbang and the results were very good, near the finish of a freshly cast piece. Anyone have any other ideas