Odors from polyurethane

[Rebel1]

It's been at least four months since I sanded the floor/shelf of my bay window down to bare wood and applied several coats of Minwax Fast-Drying Polyurethane, clear semi-gloss. Just recently it started emitting an unpleasant odor.

It faces south, so when there are no clouds, it gets direct sun for the full day (no shadows from trees). The odor is less intense in the morning, then seems to build up. At first, I thought it was from a new poinsettia and Christmas cactus I placed on the shelf. So I removed all plants from the shelf and moved them to a different room. That room did NOT develop the same odor, but the bay window room still had it. Clearly, the plants are not the source.

Putting my nose right next to the bay window shelf, I can detect the odor.

I'm in central New Jersey, so the shelf's bottom is exposed to very cold outside temperatures. (Of course, there is insulation under the shelf.) But up until when I went to Florida on Feb 3, this was not a problem. While I was away, I set the thermostat to 55 degrees. When I'm home, the lowest I ever set it is 66 degrees.

Why, after all these months, is it emitting an odor? Do you think that applying a heavy paste wax would solve the problem? Other suggestions?

Thanks,

R1

[Rebel1]

I should have mentioned that I applied Minwax stain to the bare wood before the polyurethane top coats.

[Ed Pawlowski]

Even fast drying poly needs a few weeks to fully cure. My guess is the cool temperatures and wean sun for a few month allowed it to retain some aromatics. Now that the sun is stronger and you will be keeping the temp a bit higher it may finally out-gas and stop smelling.

The wax may prolong the process. I'd try to keep it as warm and dry as possible. The sun will help.

[Dean Hoffman]

Some cut.

Would a good old fashioned fan help any?

[Ed Pawlowski]

Can't hurt, but it is mostly chemical reaction.

[Mayayana]

Have you ruled out something like a dead mouse? Four months of fumes is farfetched, and since you weren't sure whether the smell might be from the plants it sounds like you don't recognize the smell.

[Ed Pawlowski]

Good point, never thought of that. They smell after a couple of days and take a couple of weeks to stop. We had that at work and never did find the mouse. While not a good odor, it is not as bad as rotting meat or fresh feces.

[Dan Espen]

Yep, mice don't take long to dry up and stop smelling. Rats on the other hand stink badly for a few weeks.

[Stormin Mormon]

Simple, effective. Works for me.

[Rebel1]

I spoke to Minwax today. They couldn't explain why sunlight provoked an odor, especially after so many months without a problem. Their recommendation of increasing ventilation is impractical when the outside temperature is below freezing, as it is now in central NJ.

The other suggestions were to use baking soda or charcoal to absorb the odor. I'll give that a try.

R1