Iron Stain Removal and Marble Sealing Under a Lanai

Brand-new white marble under a lanai in Estero, with orange-red iron staining spreading across it only weeks after the pool was finished. The owners had been away for the season with the storm shutters down, and one shutter had effectively walled off the section of lanai nearest the sliding glass door. Water worked its way under the shutter, pooled in that enclosed pocket, and sat there. Standing water on marble is how iron staining starts — and on white stone there is nowhere for it to hide. Marble cannot be pressure washed or hit with acid-based rust removers; both etch the stone. The staining was treated with hydrogen peroxide instead, applied in several rounds with long dwell times. The first application was left to work for a full day. When we came back, most of the stain had lifted. The area was treated again and left overnight to pull out what remained, and by the next morning the marble was uniformly white. With the stone clean, it was sealed with a penetrating natural-stone sealer so that the next spell of standing water cannot soak in the same way. The visit also covered a small paver repair on the driveway and a driveway cleaning. The lesson for anyone with a new lanai in Southwest Florida: shutters left down for months can trap water against the floor, and iron staining is far easier to prevent than to remove. If you see the first orange shadow on marble or travertine, it is worth calling before it sets.