Originally Posted by evwxxx
One thing I have noticed is that if you have zinc-coated things like bolt heads or derailler hangers the Oxalic acid can dull the previously shiny surface. Not sure if this is just a dull coating that can be removed with super fine sandpaper or if it is more permanent.
I don't think it is a dull coating, I believe the acid dissolves zinc and cad platings. If you watch the process, you will see bubbles coming off the zinc and cad plating.
In the hardware store, by the oven cleaner is a brass brush the size of a oversized toothbrush. It costs about $1.50 and won't scratch your chrome. I believe its intended use is to scrub your enamel coated oven without scratching it but it works wonders on that stubborn rust.