Removing Urine Stains and Odors from Stone Surfaces

Frederick M. Hueston, Stoneforensics.com

Your new puppy made a mess on your new marble floor. The granite floor in front of the urinals in the men’s room is stained and smells of urine. These are just a few of the issues with odors emitting from your stone surfaces.  Weather it’s your puppy or your husbands poor aim the following should remove the stain and the odor.

The Chemistry of Urine

Urine is unique in that it is a substance that comes our of the body as an acid and when it starts to dry becomes an alkaline crystal. For you amateur chemist it starts at a pH of 5-6 and converts to a pH of 10-12. These alkaline crystals are hydrophilic which simply means they absorb moisture. As these crystals absorb surrounding moisture the stain can grow in size. If the stone is a polished marble or limestone it can become dull due to the initial acid reaction but can also dull from the strong alkali. If this is the case the stone may need to be repolished.

Removing the Stain

Removing urine stains can be tricky and timing is everything. The quicker you can get to the stain the easier it will be to remove.

As soon as you can blot the urine up with some dry paper towels. Do Not wipe since this will only spread the stain.  Clean the stain with some dish soap and water. Mix about one teaspoon of dish soap in a gallon of water. Apply this solution on the wet area and allow it to sit for a minute or two. Blot the solution up and rinse with clean water. If there is still a stain, then you will need to apply a poultice.

 The following is a basic procedure for stain removal More detailed stain removal instructions can be found here. http://stoneforensics.blogspot.com/ or www.SurPHaces.com

What you’ll need:

1. Flour(use only white flour)
2. Hydrogen Peroxide 20 Volume(You can purchase 20 volume peroxide at most beauty supply stores)
3. Plastic wrap (saran wrap or equivalent)
4. Plastic putty knife
5. Low contact painters’ tape
6. Mixing bowl or cup
7. Plastic or wooden spoon

1. Wet the stained area with distilled water. Pre-wetting fills the pores of the stone with water isolating the stain and accelerating the removal by the chemical.
2. Prepare the poultice.  Take a small amount of flour and pour the peroxide into the flour and stir until you reach a creamy consistency.

3, Apply the poultice to the stain being careful not to spill any on the non stained areas. Apply approximately 1/4-inch thick over-lapping the stain area by about one inch.

4. Cover the poultice with plastic (food wrap works great). Tape the plastic down to seal the edges. It also helps to poke several small holes in the plastic so that the powder will dry out. Failure to do this may result in the poultice staying wet.
5. Allow the poultice to dry thoroughly. This is a very important step. The drying of the poultice is what pulls the stain from the stone into the poultice material. If the poultice is not allowed to dry, the stain may not be removed. Drying usually takes from 24 to 48 hours.
6. Remove the poultice with a plastic putty knife. Rinse with distilled water and buff dry with a soft cloth. If the stain is not removed, apply the poultice again. It may take up to five applications for difficult stains.

Step 2 Odor removal

 Once the stain is removed the urine smell may still be present. The following is how to neutralize the odor:

The nasty smell you experience is the result of bacteria using the urine as a food source. So, in order to eliminate the odor we need to kill the bacteria. There are numerous products out there that are designed for eliminating the odor in carpets. These same chemicals can be used for stone.  If you use these products make sure they are enzymatic. Many products are only mask the odor, you want to eliminate it, so an enzymatic product is necessary.

Instructions for applying an enzymatic cleaner

• Spray the affected surface liberally with the cleaner using a pump sprayer or spray bottle.
• Cover with plastic  for 1 to 2 hours to slow the evaporation rate and allow time for the first application to soak deeply into the stone.
• Note that as the first application of cleaner goes to work, the urine odor may intensify at first. This is typical with old or heavy urine deposits and indicates that the urine being loosened and is rising to the surface.
• Remove the plastic and blot the floor dry with paper towels or cloths. Expect the blotting towels or cloths to be colored yellow and smell heavily of urine. Dispose of the soiled towels or cloths.
• Reapply the cleaner. Allow to dry 1 to 2 hours. (In humid climates lacking AC, drying may take longer.)
• Reapply as needed, with 1 to 2 hours drying time between applications, until odor is removed.

The above processes are time consuming but will be well worth the effort if done properly.