How to fix white marks left by a limescale remover on stone?
Estimated Reading Time: 2 MinutesQ. I hired a cleaner and she used a limescale remover with mold control. It appears to have left white stains on my bathroom stone tiles. These don’t wash away with water. What should I do?
A. What you’re seeing is likely etching, not staining. Etching occurs when acidic substances react with calcium-based stones such as marble, limestone, or travertine. Products like the one you describe often contain strong acids that can chemically react with the surface of these stones, leaving behind dull, whitish marks. This kind of damage doesn’t wash away because it's not a substance sitting on the surface—it's a physical change to the stone itself.
If the etched area is small and relatively smooth, that is, you don’t feel any roughness when running your fingers over it, you may be able to restore the finish yourself. In that case, a marble polishing compound designed for etch removal can often restore the shine. It contains very fine abrasives that can buff out light etching and help blend the area with the surrounding surface. Be sure to follow the product instructions carefully, and test in an inconspicuous spot first. NOTE: If the finish of your stone is satin/matte, the area you treat may appear more polished and reflective than the surrounding finish. A professional stone restoration contractor can resolve this problem. To find a vetted PRO in your area, visit www.surfacecarepros.com and click on Find a PRO.
If the etching is widespread, deep, or feels rough or pitted, a DIY approach may not be effective. In such cases, you'll need a PRO who has the tools and expertise to mechanically re-hone and polish the affected tiles. This process involves sanding the stone down to a fresh layer, then polishing it to match the original finish.
To prevent this type of damage happening again in the future, avoid using household cleaners that contain acids, ammonia, or harsh chemicals on natural stone. Instead, use stone-safe, pH-neutral cleaners specifically formulated for stone surfaces.
ABOUT THE AUTHOR Fred Hueston is the Chief Technical Director at SurfaceCarePROS.com and Director at StoneForensics.com. He is also the author of Stone and Tile Restoration: The Manual, a comprehensive online manual for stone and tile restoration contractors. [Learn more about Fred.]