The previous owner of our West Seattle cottage left behind an ancient metal chiminea, which had drizzled a rusty stain onto the patio. But not just any rust stain: This one had really hit its mature stride, crusting corroded metal onto the unsealed paver surface — sort of like iron-oxide barnacles. They had a tenacity I both respected and learned to loathe.
Here’s how I went about getting rid of the stubborn stain, and what I learned along the way.
Hydrogen peroxide. Expert after expert cautioned against the common wisdom of lemon juice or white wine vinegar on natural stone. So instead, I applied 3% hydrogen peroxide, then scrubbed with a nylon brush like Cinderella drudging for her evil relatives. I let this sit for 24 hours, then hosed the patio down. The stain’s color shifted slightly from scarlet to Mars orange. Fail!
Abrasion. Still trying to avoid heavy chemical solutions, I went rogue. I attacked the pavers with a crimped wire cup brush attached to a hand drill, an extreme but effective technique. It ground down those iron-oxide “barnacles” beautifully. But after a half-hour of jarring effort, I had buffed away maybe one-twelfth of the stain — and its ghost would cheekily rematerialize whenever the stone got wet. Note: Do not try this on your own pavers unless you’re willing to risk wrecking them. (I was lucky not to.) As the Natural Stone Institute warns, “Deep-seated, rusty stains are extremely difficult to remove, and the stone may be permanently stained.” It suggests diatomaceous earth and commercial rust remover, blended to the consistency of peanut butter. Dampen the stone, apply the poultice a half-inch thick, then cover it with plastic and tape down the edges. Remove this after 24 hours, then let the paste dry for another day before rinsing. This process may need to be repeated up to five times.
Rust remover. I don’t possess the patience for 10 days of poulticing the patio, so I turned to Iron Out, a plant-safe liquid containing oxalic acid. Wearing safety glasses and chemical-resistant gloves, I applied a first coat. Within 15 minutes, the rusty ring had faded to the Space Needle’s original Galaxy Gold hue, revived for its 60th anniversary this year. I rinsed and repeated. After three additional rounds, the Mighty Stain was finally no more.