Works great on bluing...will not remove stains. Takes some time and patience. link to a video: http://www.youtube.com/watch?v=l_nSgyWR8dw. Best to wrap the cloth around something made of soft pine like a carpenter's pencil.
It works up to a paste...doesn't seem to be extremely abrasive and it does take a good bit of elbow grease. I used after AI removal. Pipes blued again shortly thereafter to just past the first bend in my headers but the bluing was not as dark or severe as before Blue Job--probably because of the AI removal. I happen to prefer some blue.