Frederick M. Hueston, PhD

I was sitting at my favorite greasy spoon shootin’ the breeze with Flo when my phone rang. “Stone Detective here,” I said, as I almost spilled coffee on my trench coat.  I excused myself and started to head outside to take the call. As I stood up, the admiral, one of the regulars, started one of  his war stories – loudly – as if he didn’t know I was on the phone. I just ignored him and walked out the door.

The caller was really upset, crying and mumbling something about her husband’s unacceptable bathroom habits, she just couldn’t take it anymore. She went on and on about how sloppy he was, leaving his bath towel on the floor, as well as his dirty clothes – which the tossed on the floor, next to the hamper, rather than inside it. 

As she went on cataloging his shortcomings, I began to wonder if she had called the wrong number – like maybe she thought she’d called her therapist. After all, this seemed like a job for a marriage counselor, not a stone and tile guy.

So, I interrupted her rant and asked her how I could help. I thought she was going to ask me for a consult, but she said she had an issue with the marble floor in her master bath. I had no idea what her rant about her husband had to do with it, until she told me she had this awful smell and stain on her marble floor, and that her husband has poor aim. She went on to describe in detail how poor his aim is. I’ll spare my readers the details, but I’m sure you can imagine what I’m talking about.  

She asked how to get rid of the odor and the stains resulting from her husband’s inaccuracy. Well, this was one of those cases where I wouldn’t need to inspect the problem, nor did I want to.  I started to tell her, and she continued on about how much of a slob he was and something about the mess in the garage. I just let her get it out of her system for about five minutes. When she finally calmed down, I told her the following:

“Urine is a unique substance. It comes out of the body as an acid, and when it starts to dry it becomes an alkaline crystal. It starts at a pH of 5 to 6, and converts to a pH of 10 to 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.”

I went on to tell her that 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 the area, since this will only spread the stain. Clean the stain with a mix of about one teaspoon of dish soap to 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.

“Once the stain is removed, the urine smell may still be present. Here’s how you can neutralize the odor:

“The nasty smell you are experiencing 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.  But if you use these products, make sure they are enzymatic. Many products only mask the odor, and you want to eliminate it, so an enzymatic product is necessary.”

I also gave her the following instructions:

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 odor may intensify at first. This is typical with old or heavy urine deposits, and indicates that the urine is being loosened and is rising to the surface.

You will want to use gloves for this step. 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 environments lacking AC, drying may take longer.

Reapply as needed, with 1 to 2 hours drying time between applications, until odor is removed.

I almost added that she might want to try those little boats in the toilet –you know, the ones you potty train little boys to aim at? 

However, that’s not my call, and way beyond my expertise, anyway. Another case solved, with some free venting therapy thrown in.


The Stone Detective is a fictional character created by Dr. Frederick M. Hueston, PhD, written to entertain and educate. Dr. Fred has written over 33 books on stone and tile installations, fabrication and restoration and also serves as an expert for many legal cases across the world. Fred has also been writing for the Slippery Rock for over 20 years. 


Send your comments to fhueston@stoneforensics.com.