I just used limeaway on a sink that had some minor calcium carbonate deposits on it around the faucets. The faucet assembly is chrome and a very expensive hot/cold mixer. I let the limeaway sit for 5-10 minutes then rinsed only to find that the chrome faucet had been permanently discolored. It is now mottled black and chrome. Nothing seems touch it. This sink is in our recently remodled kitchen and will have to be replaced unless there is a fix????