Q: I had a new red oak floor put down. At each board end, where the boards meet, there is a dark color developing, almost as if the oak were wet. What causes this, and should I worry about it occurring once the poly is down? Is this tannin?
A: It’s possible this is caused by microscopic fungal spores. You could do a search for blue dye stains in hardwood. I don’t think there is any way to get rid of it now that it left the drying kiln.
Somebody may also want to put a moisture meter on those areas to make sure it’s moisture is within specifications, 7-9%.