White spots on floor

Q: I have Douglas fir floors in my upstairs bedrooms, and in two of the rooms I’m getting milky white spots all over the floor. They look like water stains, but I don’t think they are, because they’re all over the place. I put a dog bed by the window in the master bedroom about 3 months ago, and the spots are the worst around the dog bed, you can see where the bed has been sitting.

They weren’t on the floor when we moved in, and they keep appearing!

A: Certain types of finishes do ‘white spot’ when some type of liquid is spilled on them. Wax, shellac, and lacquer for example. Could be your dog is drooling and this is the result.

Blotchy blonde spots on floor

Q: My 1818 house is located in VA. It has various additions with differing pine floors. I’m trying to identify the cause of the large and small blotchy “blonde” spots that are mostly (but not limited to) the south side of the house on the second floor.

It might help to know that last year (2018) was especially rainy and damp. In the fall the flooring cupped especially the flat sawn areas where most of the “blonde” blotches are. I was told that the cupping would eventually lay down and it did. The worse “blonde” area has affected four side-by-side flatsawn boards. However, the floor finish is perfect where a floor joist cuts through the middle of this “blonde” area.

I had a local wood floor finishing professional look at what’s happening and he didn’t offer any explanation as to what is causing these “blonde” areas. I have photos but don’t see anywhere to post them.

A: One thing that is a near guarantee with pine and other softwoods is that it will shrink and leave gaps between boards. Often these gaps can be rather wide. I would not expect to see cupping on a floor like this unless a significant amount of water came into contact with the wood over a period of time. Wood cups (that is, the edges of the planks curl upward) when there is enough water under the boards to cause serious instability. They crown when that moisture instability is caused by the surface of the floor. I suspect you have had some water come in under the floor. The new joist stopped the advance of the moisture.

Given the age of the floors, it would not surprise me if they are finished with shellac. Shellac is made from the secretion from the laq beetle and naturally contains wax. There is a version with the wax removed but that would not have been available long ago. Any wax finished item will get spots if you spill a liquid on it. So, if this is the case, it is moisture in the shellac coating. If there is a way to remove it without removing the finish needs to be a project for you.

I know there are a lot of articles on the internet about this and you may find some things to try. I will say that sanding off shellac is not a fun job. The wax in the finish will heat up and smear. It isn’t a durable finish though it dries fast. But it is permeable and subject to getting marks like this. I lived in Niagara for four years and came across several floors finished with shellac. It wasn’t easy.

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