Grey spots in finish

Q: I took on the project of refinishing my red oak hardwood floors and I’ve came to a standstill.

I rented a belt sander and vibrating sander to sand the floors down. After this, I applied an oil-based stain and let it dry for a couple of days. The next step I applied a coat of minwax satin polyurethane (oil-based). It looked great applying it.

The next day the floor had places that were grey in color in spots and other places that looked like the poly really soaked into the wood. I haven’t light sanded or applied a second coat without consulting someone about this. I’m in the process of having my house remodeled and a new central heating/air unit installed. I have no air and I’ve been opening windows and using fans to help dry the polyurethane. The weather had been real humid the last week.

A: It is quite normal for the first coat to soak well into the wood and present a blotchy appearance. I would make sure it is dry before lightly sanding with fine abrasive and applying a second coat. If the finish is dry, you will get a bit of fine powder from the finish when sanding it. Apply thin coats.