Removing Urine Stains and Odors from Stone Surfaces
By Frederick M. Hueston
Your client’s new puppy has made a mess of their marble floor. Or the granite floor in front of the urinals in that lobby bathroom smells like urine and has dark stains. These are just a couple of the stain and odor problems you might deal with on stone surfaces. Whether it’s a new dog or someone’s poor aim, here’s how to get rid of both the stain and the smell.
Understanding Urine Chemistry
Urine starts off acidic when it leaves the body, but once it begins to dry, it becomes highly alkaline. For those who care about pH, it comes out around 5 to 6, then dries to about 10 to 12. Once dry, it forms alkaline crystals that love moisture. These crystals absorb water from the air or surrounding materials and can cause the stained area to grow. If the stone is marble or limestone, the acidic part of the urine can etch the polish, and the alkaline part can dull it even more. In those cases, the surface might need to be re-polished.
How to Remove the Stain
Time matters. The faster you act, the easier the cleanup.
If the urine is still wet or moist when you arrive, start by blotting the area with dry paper towels. Don’t wipe, just blot to avoid spreading the stain.
Next, clean with a mild solution: one teaspoon of dish soap in a gallon of warm water. Pour or sponge the solution on the spot, let it sit for a couple minutes, then blot again. Rinse with clean water.
If a visible stain remains, you’ll need to apply a poultice.
You’ll need
- White flour
- 20 volume hydrogen peroxide (available at beauty supply stores)
- Distilled water
- Plastic wrap (like Saran Wrap)
- Plastic putty knife
- Low-contact painter’s tape
- Mixing bowl
- Plastic or wooden spoon
Steps:
- Pre-wet the stained stone with distilled water. This helps isolate the stain and speeds up the chemical reaction.
- Mix a poultice: Combine flour and hydrogen peroxide until it’s a thick, creamy paste.
- Apply the paste to the stained area, about 1/4 inch thick. Let it extend one inch past the edge of the stain.
- Cover the poultice with plastic wrap and seal the edges with tape. Poke a few small holes in the plastic so the mixture can dry.
- Let it dry completely, usually 24 to 48 hours. The drying action pulls the stain into the paste.
- Once dry, use a plastic putty knife to remove the dried poultice. Rinse with distilled water and buff dry with a soft cloth.
- If the stain remains, repeat. You might need to do this up to five times and it may require multiple trips to the jobsite.
Now for the Odor
Once the stain is gone, the smell might linger. That odor comes from bacteria feeding on the urine. To get rid of it, you need to kill the bacteria, not just mask the smell. Look for an **enzymatic cleaner** — the kind used for carpet pet stains.
Steps:
- Spray the affected stone with the enzymatic cleaner using a spray bottle or pump sprayer.
- Cover the area with plastic for one to two hours. This slows evaporation and allows the cleaner to soak in.
- Don’t panic if the smell gets worse at first. That’s normal and means the cleaner is working.
- Remove the plastic, then blot the area dry with paper towels or cloths. They may come up yellow and smelly. Toss them out.
- Reapply the cleaner and let it dry again.
- Repeat the process as needed until the odor is completely gone. Again, this may require multiple visits.
Yes, it takes time and patience. But if you do it right, it works — and your client’s stone surface won’t just look clean, it’ll smell clean too.
