How to remove post-construction spots on soapstone countertops?

Q. We have a new construction home with dense soapstone. Throughout the house, including the wood floors, tile floors, granite composite sink, and soapstone countertops, I am seeing marks that look like drips or drops. All of the spots are lighter in color, but the discoloration is most noticeable on the soapstone. The countertop installer came out to inspect the problem but could not identify the cause. I am not confident they are very familiar with soapstone. Does anyone have ideas about what might be causing this or how to address it?

A. Based on your description, the most likely cause is actually a pretty common one, that is, water marks. The reason your installer was puzzled is simple. Soapstone doesn’t behave like granite or quartz, and if you don’t work with it often, it can look like something’s wrong when nothing is.

The biggest clue about what is going on is that you’re seeing the same drip or drop patterns on multiple surfaces, wood floors, tile, the composite sink, and the soapstone. Soapstone just makes these marks more obvious because of how it reacts to moisture. Soapstone darkens when it’s wet and lightens as it dries.

In a brand new house there’s bound to be a lot of moisture floating around because of cleaning, HVAC condensation, and other post-construction sources. Water drips, splashes, or mists may settle and then evaporate unevenly. On soapstone, the moisture leaves lighter spots that look like stains but aren’t.

Here’s an easy test you can perform. Wipe one of the light spots with a damp cloth. If it temporarily darkens and blends in, you’ve got your answer. That means it’s likely not etched, stained, or permanently marked. It’s just uneven moisture exposure.

Here's how to fix this problem. Give the stone a thorough wipe down with plain water and a soft cloth. This will even out the surface moisture. Let it dry naturally. Don’t spot dry it, because uneven drying will create the same marks again. Once dry, apply a light coat of mineral oil (or a soapstone wax if that’s the look you want). This will darken the stone uniformly and hide water marks completely.

If the spots come back, it just means the stone is doing what soapstone does when there's moisture around. Over time, as the house fully dries out and the stone gets a consistent patina, this should stop being an issue. You can speed up the moisture removal process by running dehumidifiers and your air conditioner, which works like a dehumidifier.

We're pretty confident this will clear up in time, but if you're still seeing these spots after following the suggestions above and giving ample time (possibly weeks) for moisture to clear, there's another possible cause: exposure to cleaning or installation chemicals used during construction or final cleanup. Again, if this were a defect in the soapstone itself, you would not be seeing similar lightened marks on other materials throughout the home. 

Acidic cleaners, solvents, or strong degreasers can strip oils, finishes, or sealers and leave behind lighter drip or splash marks. When that oil is removed unevenly, it can make your soapstone to appear lighter in spots even though the stone itself has not been damaged.

A simple way to confirm this is to clean a small test area with mild dish soap and water, let it dry completely, and then apply a thin, even coat of mineral oil or soapstone wax. If the light areas darken and blend in, it confirms that the issue is oil loss rather than permanent damage.

This can improve the appearance, but it may only be a temporary fix. If the spots reappear, try sanding the stone first with 120-grit sandpaper, followed by 220-grit. After sanding, reapply mineral oil or wax.

The last thing you'll want to do is repeatedly oil the stone with uneven or short-lived results. If neither of these DIY methods work, contact a professional stone restoration contractor. A qualified professional can determine exactly what caused the discoloration and restore a uniform finish using methods appropriate for soapstone. Knowing the real cause of the problem will also help you avoid trial-and-error fixes with other affected materials.

To find a vetted PRO in your area, visit www.surfacecarepros.com and click on Find a PRO.

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.]