Manufacturer claims stains caused by hardwood floor cleaner

Q: We had an engineered wood floor in American Cherry finish installed throughout the Living, Dining, Family Rooms and Kitchen (1000 sq. ft., open concept) about one year ago. Approximately 6 months ago we started to notice dark stains appearing along the edges and ends of the planks, which we assumed to be water stains.

The house is 30+ years old, concrete slab on grade, which was previously carpeted. In some cases the stain spans across the width of the plank (3 1/2′). We contacted the installer who advised us that he had never seen this before and had the manufacturers rep visit for an inspection.

The manufacturer now says that these stains are caused by our use of hardwood floor cleaner, which we purchased especially for these floors. We maintain that this cannot be so, we are very careful to follow all recommendations regarding maintenance of these floors.

We use the cleaner infrequently, spray only a small amount directly onto the mop and ensure that the floor is dry after use. In addition, we have never cleaned under the area rugs with cleaner, and yet the stains extend under the hall runner. They also appear to be localized in the hallway and living room areas which indicates to me that the material used in these areas may have been wet when installed. I also cannot understand how any floor cleaner could have penetrated across the full width of the plank as it has done in some areas. We need advice on how to handle this problem which we believe is getting worse.

A: Very interesting problem, but not funny! Like yourself, I don’t believe using a recommended floor cleaner will cause this problem. Even if you misted a small amount onto the surface of the floor from a spray bottle, you shouldn’t see this problem. And you aren’t doing that, but spraying onto the mop first, which is the recommended way.

These floors are top coated with, probably an aluminum oxide finish, is that correct? Any evidence of finish peeling or degradation? I’m leaning toward this being a defective product.

Is there any chance this black marking is mold?