How can a water ring be removed from a limestone hearthstone?
Estimated Reading Time: 2 MinutesQ. I have a water ring where a plant was sitting on my hearthstone, which I believe is limestone. Is there any way to remove it? I appreciate your help.
A. Limestone is beautiful but porous and sensitive to moisture. Water rings left behind on stone by potted plants is a common issue. These marks form when moisture sits on the surface for an extended period, either leaving mineral residue as the moisture evaporates or causing etching by slightly dissolving the calcium in the stone. Etch damage typically shows up as a dull or lightened ring and will not wipe away. Technically, etching isn't a stain at all. It is a chemical alteration of the stone's surface.
The most important step in addressing a water ring on limestone is to act promptly. In some cases, allowing the stone to dry completely for several days may cause the mark to fade on its own.
If the ring remains, gently blot the area with a damp microfiber cloth. Clean the surface using warm distilled water mixed with a few drops of mild dish soap or a stone-safe cleaner, wiping lightly in a circular motion. Rinse with distilled water and dry thoroughly with a soft cloth. For something stronger, try cleaning with heavy duty soap film remover.
If the water ring persists, a poultice can help draw out trapped moisture or minerals. For detailed, step-by-step instructions on how to mix and apply a poultice correctly, check out our free Stain Management App. Your poultice ingredients will be baking soda and distilled water. If the mark is improving but not fully gone, just keep reapplying poultices until it disappears completely. Keep in mind the stone may need to dry out after your final poultice application.
If the ring appears dull, chalky, or feels slightly rough compared to the surrounding stone, it is likely etched rather than stained. Etching cannot be fully corrected with cleaning alone and usually requires professional honing and/or polishing to restore a uniform surface. If DIY methods do not resolve the issue or there is concern about causing further damage, contacting a professional stone restoration contractor is recommended. To find a vetted PRO in your area, visit www.surfacecarepros.com and click on Find a PRO.
After restoration, applying a penetrating sealer and using protective measures such as trays under plants can help inhibit future water rings on limestone. Your PRO can select and properly apply the most appropriate sealer.
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.]