Frederick M. Hueston, PhD  

Stone Care Consultant 

I arrived in Las Vegas ready to start my stone inspection seminar. Being as eager and excited as I was, I got to the classroom and soon realized that I had to go to the bathroom.         

I walked into the restroom and, being the stone maestro that I am,  noticed that the floor was a white carrara. I also couldn’t help but notice that under the urinals the floor looked to be destroyed. It was pitted and discolored. 

I shook my head and wondered why the designers and architects put marble under urinals. Anyway, and to keep from giving TMI, the pitted marble turned out to be somewhat of a mystery as I was to find out a few days later.

OK, now it’s a few days later, the class is asking questions as fast as a dog chasing its tail. One question in particular was very interesting. One student who would not shut up, asked, “What causes the stone under the urinals to pit?” 

I’m usually not taken so off guard, but I looked at the student who seemed ready to debate my answer. I knew this ’cause he argued with every question he asked.  

I said, “The answer is very simple, urine is acidic and, as you know, acids will etch marble.” Now, how could he possibly argue with that? 

He immediately said that I was only “partially correct.” OK, so now I had to prove to Mr. Know-It-All that I was completely correct, and why. Being as this was probably best taught hands-on (so to speak), I took all the students to the restroom with some pH strips in my hand.  

Everyone gathered around me as I placed some distilled water on the marble floor. I smiled and took the pH strip and placed it on top of the distilled water. The entire time, Mr. Know-It-All was smiling. Apparently he thought he knew something that I didn’t.  I couldn’t wait to show him that the stone had an acidic pH.  

I smiled back at him, picked up the pH strip and showed everyone that... Holy $#^+, the pH was alkaline, not acidic. Mr. Know-It-All had me! 

So, I asked him how he knew it. Come to find out, he was a carpet inspector and has dealt with urine stains and damage on carpet. He said, “Urine is acidic in the liquid state and when it dries, it forms uric acid crystals that are alkaline.” Made sense but I couldn’t wait to look it up that night on Google.

Somewhat defeated, I finished up class and headed right for the bar. After a day like that I needed a drink, but I still couldn’t wait to check out Mr. Know-It-All’s explanation. 

So, I actually bypassed the bar and headed back to my room just to see if his story checked out.  

I opened my laptop, went to Google and thought, What do I type in the search box? Hmmm, maybe I should have had that drink first. 

After a moment of thinking, I typed in the following: Does urine go from an acid to an alkaline? To my disbelief the first thing that came up was an explanation and guess what? Mr. Know-It-All was right. 

This is why I love the stone industry; even an old man like me can learn something new. And this was definitely one of those times where the teacher became the student. Anyway, another case solved, even if by default.

The Stone Detective is a fictional character created by Fred Hueston, written to be entertaining and educational. He 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. You can send any email comments to him at fhueston@stoneforensics.com.