I don't know how concentrated this stuff is that you buy commercially, but its pretty harsh stuff in industrial applications. Its an acid isn't it? I have seen flange bolts you couldn't budge with an industrial wrench, put this stuff on, go for break, come back and spin the nuts off with a combination wrench. It's also very carcenigenic, so be careful not to get it on your skin, if it can penetrate a rusty old bolt the way it does, it has no problem getting thru your skin.