Hello, complete amateur. I recently converted my stair treads from carpet to hardwood, red oak to be exact.

I’m using Minwax oil-based stain and General Finishes water-based poly. Of about 15 treads, one is giving me troubles. First time application, I applied the stain and then 4 coats of poly, following normal procedures, allowing 4-5 days for the oil-based stain to off-gas. However, the poly had a milky look to it.  (SEE ATTACHED PICTURES)

So I sanded it back down to raw wood and applied the stain again. I then waited 3 weeks, just in case the 4-5 day period I had used previously wasn’t enough time for it to off-gas. I then applied a single coat of the poly and same issue. However, the milky look is very inconsistent across the tread. There are some areas where it’s fine and then others where the milky look is present. In addition, there’s weird white spots in the negative grain.

I’m suspicious of the wood, thinking it’s contaminated in some way. Again, all of the other treads turned out beautiful and I did nothing different in my application method.

Any wisdom to pass along?
–Chris