I Removed Rust Stains on Concrete
When I purchased my home two years ago, the front porch had two large rust stains where metal flower pots had been on each side of the front door. I had tried bleach, CLR and other rust removers with no luck. I recently had my driveway and sidewalks power washed and asked if they had any way to remove these stains - they said they would use their special rust removing chemicals but the stains were still there when they left.
I have finally TOTALLY removed the rust stains. I'm sure this is not a recommended use of the product, but 'The Works' toilet bowl cleaner, poured full strenght onto the stain worked like magic. I know, I know, the bottle warns to ONLY use on toilets - but it worked like a charm. This is hydrochloric acid, so you have to be very careful with it. I hosed it down liberally and made sure that nothing else would get damaged by any of the solution. My only problem now is that the area that used to be stained is so much brighter and whiter than the rest of the porch - a problem I'm happy to live with.