Frederick M. Hueston, PhD

I grabbed my fedora and headed out the door to my favorite greasy spoon for a cup of joe and some breakfast. Just as was walking out the door I tripped  over a shoelace, stumbled, and almost fell on my face.  Little did I know that later that day I’d again be that clumsy, and it would help solve another stone mystery.

Luckily, I caught myself before I had a nasty tumble.  I looked around and noticed the old lady across the street staring at me. I tipped my hat and looked back at where I had stumbled and pretended that I tripped over something on the ground.  She just rolled her eyes and shook her head.  I hopped in the ole Woody feeling a bit embarrassed at being eye-rolled by my silver-haired neighbor. I hope my eyes are still that eye sharp when I’m her age.

I opened the door to the diner and almost tripped again.  This time I didn’t think anyone was looking until I sat down. Flo was pouring me a cup of joe and quipped, “Good Morning, hope you had a nice trip over here.” LOL… well I guess she noticed, after all.  I took a sip of my coffee and ordered my breakfast. I wanted to make sure I had something in my stomach for the long ride to that afternoon’s inspection. I finished my ham and eggs, said my goodbyes to Flo and the regulars, and I was off for a four-hour drive to look at some mystery stains.

limestone flooring had some brown stains appearing without a known causeThe inspection sounded interesting. A builder had called me last week with a problem: some limestone flooring had some brown stains appearing without a known cause. Based on his description, it sounded like your typical moisture issues where the iron in the stone was oxidizing. So, I told him I could come down and take a look, record some moisture readings, and try to find out where the moisture was coming from.

I arrived at the address – a huge house. When I say huge, it was as long as a Walmart store, and looked just as big. Later, I would find out that the house sold for over 60 million dollars. I parked the Woody in the circular drive and headed for the front door. There was no doorbell, but a pair of large brass door knockers. Kind of reminded me of the movie Young Frankenstein. All I was missing was lifting Teri Garr off  the carriage and making the comment… never mind. Those of you who saw the movie know what I’m talking about.

A tall gentleman answered the door,  who with a little makeup could have doubled for Frank Boyle playing Frankenstein.  He opened the door and asked me to come inside. 

I was hoping he would have said” “walk this way.” Sorry – another inside joke from Young Frankenstein.  

He led me to an area on the floor and just pointed to it.  This section of the floor had a streaky brown staining pattern (see the pic above). I immediately took out my moisture meter and discovered the entire area was wet. When I took moisture readings in other areas, they were dry. 

So, my next step was to ask some questions to see if I could determine the source of moisture. Mr. Frankenstein assured me that there were no leaks anywhere.  I considered asking if I could remove a tile, but I stood up and tripped on my tool bag and almost landed on my face. Fortunately, I was able to put my hands out and fell like I was doing a push up. I was about to get up when I noticed an unusual, unpleasant smell. So I crawled around on the floor like a dog sniffing the grass.  Funny I should say dog, because the entire area smelled of eau de pooch.  I got up and grabbed my blue light and shined it on the floor. The floor glowed like Chernobyl! I looked around and saw no signs of dogs, so I asked if there were any dogs in the house. 

Bingo! The owner had two little dogs. I asked what the maids used to clean the floor. (Yes, there was more than one maid.)  He led me to a closet in the laundry room where I discovered a floor cleaner. I looked at the back and really couldn’t find any info, so I took out my phone, googled the name and, lo and behold! It had a pH of 10 – way too alkaline for everyday cleaning.

Apparently, the two little pooches were peeing on the floor and the maids were cleaning it up with this cleaner.  They were in fact  flooding the floor with the cleaner, and mopping it up. This saturated the pores of the stone and caused the iron in the stone to oxidize. In other words, the stone was rusting.  Once I discovered this, I was able to see that the brown discoloration had streak marks resembling mopping patterns.

Another case solved. I guess I better add olfactory detection to my list of inspection tools!

One final note: Frankie asked for a recommendation with my written report. I told him he could hire a restoration specialist to hone out the stained limestone flooring. I sent him the names of some reputable, certified contractors. Now, if only he can keep the pooches out of the foyer…

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