We've had a number of customers who have used our Concrete Rust Remover on their stone patios. To show how well it works we decided to demonstrate it on a flagstone patio. For this particular rust stain, the stain was created by an old metal bird feeder. The bird feeder developed a lot of rust on the chain. During rains, the rust stained water caused a stain to develop on the stone. After many years, the stone had a deep orange rust stain.