Frederick M. Hueston, PhD

This ole Stone Detective has been in the stone industry for a long time. Over the last 40 years, it has certainly changed. The following case I recently solved has become more common in the past few years. I would go as far as to say it is growing at an alarming rate.

I was sitting in my favorite spot at my local greasy spoon talking to Flo about the town’s upcoming parade when my phone rang. I excused myself and walked outside to take the call. 

“Stone Detective, here,” I said. The man on the other end sounded very businesslike. He told me that he was an architect and about a year ago, they finished a 90 million dollar building. The granite they used for cladding was getting stained. He wanted to hire me to come out there and see what was going on and if there was a chance of removing the stains. 

Well, stain removal is right up my alley so I told him I could get out there as soon as I could book a flight. He said there was no need to book a flight – they would send their Lear jet out to pick me up tomorrow morning. 

Holy Cow, I thought. Must be serious if they’re sending a private jet. I also thought it was a sign these folks must have some dough. 

You should know by now that I am used to dealing with wealthy (and eccentric) people, but I’ve never had one pick me up in their private jet. 

I was looking forward to this. I told him I would be at the airport in the morning with my test kits. Normally I could not bring my chemicals on a plane, but since this was a private jet, there would be no problem.  

I arrived at the local airport at 8:00 the next morning and there was a young pilot waiting for me. He introduced himself and asked me if I was ready. I almost said no. The reason? This kid looked like he just got out of high school!  I guess I must be getting old. 

He asked if I wanted to sit up front with him in the cockpit, and I jumped at the opportunity. We taxied for takeoff and soon we were on our way to the west coast. 

I’d tell you about the great conversation I had with the pilot… but this story is about the stained granite.  

A limo was waiting for me at the airport and took me directly to the building. As we pulled up, I noticed right away that the granite was stained with what looked like rust. 

There were five “suits” waiting for me as I got out of the limo. One of the well-dressed gents told me he was the architect that spoke to me on the phone. The others were representatives of the building owners. They all introduced themselves and asked me what I needed to get started. 

I asked them the normal questions. How old was the building? When did they first start seeing the stains? Etc., etc.  As I was asking my questions, the architect told me that they originally had specified a local granite source but it was too expensive, so they found a similar granite from China at less than half the price.  The minute he said that I knew what was causing the problem. 

Now, please do not send me any hate letters or emails, but I have noticed that some of the beautiful and cheap granite coming out of China has a very high iron content and is prone to oxidation. This is exactly what was happening here. The building was in a city that experienced high humidity during the warm months, and when this happens iron will begin to oxidize.  

I simply told them I needed some time to examine the granite and perform some tests. What I really needed was time to think about how to break it to them. They all gave me their cards and asked me to call them when I was done.

Fortunately, the rust stains were on the surface and came off very easily with a mild oxalic acid solution. This was the good news, but the problem was it would certainly come back.  I could recommend a sealer but I am not a fan of sealing exterior stone for many reasons. After about an hour or so I was finished with my inspection and called the men in black for the verdict.   

They all arrived within 15 minutes of my calls. I told them that some granites from China are prone to rusting and they happen to have one of these granites.  I told them it could be removed but there was no guarantee that it would not return. Needless to say, they were not happy and asked me if there was anything they could put on the stone to prevent it from happening.  I told them we could try applying an impregnating sealer but there were no guarantees. To make a long story short, they applied the sealer after some extensive testing and a few jet rides, and so far, after two years, the stains have not returned. 

So my advice to you? Just be aware of the hidden potential of some of these granites from China; don’t fall victim to the China syndrome!

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.