Frederick M. Hueston, PhD  

Stone Care Consultant 

I was sitting next to this old man at my local greasy spoon. He was going on and on about his time in the Navy.       

He just kept telling me one boring war story after another. Now, I am not complaining, I honor our vets for all they have done for us, but this guy was starting to get on my nerves. 

I ordered my breakfast and, thank goodness, my phone rang. I looked at him and put my finger up to my lips, making a motion for him to be quiet. It didn’t work, so I took the call outside.  

“Stone Detective, here. How can I help you?” The voice on the other end was very nasally. It was a woman with a voice that reminded me of the phone operator that Lilly Tomlin played. She said she was from a tile importer and she told me that they had a huge shipment of limestone that had these “mystery pink spots.”  

“I see,” I said curiously. “Would it be possible for you to send me a few tiles and I’ll see if I can determine what they are?” 

She snorted and said, “Well, of course.” So I gave her my address and went back inside to eat my breakfast and to hear more war stories from the old admiral.

Several days passed and my nerves were on end waiting to get those tiles. My luck was finally with me since there was eventually a big package waiting for me at my front door. The box was huge and for a moment I was wondering why. I found out when I opened it. 

These tiles were huge! I was expecting your standard 12 x 12 or maybe 18 x 18, but these tiles measured 30 x 30 inches. This must have cost them a fortune to ship, I thought. I unpacked the tiles, took off the miles of bubble wrap and, lo and behold, there were these pink stains all over the tile. 

Now, pay attention boys and girls. I am about to tell you how I go about testing and discovering any mystery stain. The first thing I did was take out my camera and snapped a few pics. I also made sure to put a ruler in the photograph so I could have a record of the stain size. 

I next took a pencil and circled the stains. What’s the reason I do this, you ask? If I am successful in removing the stain, I will know where the stain once was. 

I took out my portable hand microscope to examine the pink stains. Under magnification I noticed small fuzzy spots. My gut reaction was  that this was some type of biological growth. So how do I get rid of mold, mildew, algae, etc.? Bleach or peroxide? 

Both work well, so I took a drop of bleach and placed it on one of the pink spots. Within 10 minutes the spot was gone. OK, now I know what the stain is but how did it get there? It’s time for a biology lesson. 

Mold and mildew need several things to grow, mainly a food source and moisture. Crates of tiles in containers can get very moist but where is the food source? The source must be something organic. The stone may have organic matter in its makeup or there is an outside source.  

I called “Lilly” back and asked her if all the tiles in the crate had these spots or were there just a few? 

“No,” she said, “but most of the tiles on the perimeter of the crate were a problem.” 

“Is the crate wood?” I asked. 

She snorted again then said, “Why, yes, it is!”

Bingo! Wooden crates can sometimes serve as an organic source of food. Another case solved. Guess I’ll go grab some lunch, now. All this talk of food sources has made me hungry.

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.