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

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

On 3/1/2014 4:35 PM, Rebel1 wrote:
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).

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.

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.

Rebel1:

Well, besides phoning the manufacturer's 1-800 customer service phone number to see if anyone else has experienced this same problem with their product, I would try covering the window sill with wax paper, taped down with masking tape to see if the smell dissipates in the room while it's covered. You could also use aluminum foil, but aluminum foil is much more difficult to work with because it tears so easily. I expect Saran Wrap would also work, but I don't know if it would work as well as wax paper.

There are many kinds of polyurethane plastics, but the conventional "oil based" polyurethane that became the clear coat of choice over hardwood floors in the mid-1950's is really just a modified alkyd resin, and it uses mineral spirits to thin it just like alkyd paint. So, if what you're smelling doesn't smell like mineral spirits, then there's sumthin funky going on.

There are also something called "isocyanate" based polyurethane coatings that can have a strong smell, but only while they're curing, not 3 months after they finish curing. If you had to mix the polyurethane together with a small amount of liquid hardener before you applied the stuff to the window sill, then it was an isocyanate based polyurethane you used. These have been known to cause "sensitization" in people, so that once sensitized to that smell, you become ill if you are exposed to it. In that case, it may be that the smell was always there, it's just that you became sensitive to it in the past 3 months.

If covering the sill with wax paper eliminates the smell, then I'd look for Minwax Wipe-On Polyurethane in your local home center. You should still be able to buy it, or at least we can still buy it here in Canada. Sand down the polyurethane you put on, and then apply a coating or two of the Wipe-On polyurethane with a white cotton rag. You want to use white cotton so that there are no dyes in the rag that can dissolve into the polyurethane and discolour it. Also, keep the rag wrapped in a plastic bag in your freezer between coatings to prevent the polyurethane from curing between coats and the rag turning hard on you. Maybe mask off everything you don't want to get the Wipe-On polyurethane onto with masking tape.

I'm suggesting the Wipe-On poly because you'd only need a thin coat to encapsulate the smell, and Wipe-On polyurethane is very thin so that it self levels immediately so that you don't have to be concerned with brush strokes.
However, you can also thin it with mineral spirits if you so choose to put on even thinner coats.

I use Minwax Wipe-On Polyurethane to repair the wooden suite doors and sliding doors in my building. Occasionally, tenants will spatter something onto them that won't come off with water. I have to use acetone to clean them, and the problem is that acetone or lacquer thinner will dissolve the old varnish on them so that a "dull" spot will remain. I use Wipe-On poly thinned with mineral spirits to go over those spots just to make the surface of those dull spots smooth again, so that they disappear.

Also, you should know that it's a common misconception that oil based products will always yellow with age. While that's true for oil based paints that spend their life in dimly lit conditions; like inside a closet. But, it's not true for situations where the paint is exposed to direct or even indirect sunlight, like a window sill. This is why exterior oil based paints that are used outdoors never yellow with age. When you see someone painting the outside of their house white with an oil based paint, that white stays white, it doesn't gradually turn yellowish. Even the north facing side of the house will stay white as the day it was painted because even the north side receives indirect sunlight from the sky. This is also why you never hear of "yellowed" picket fences, you only hear of "white" picket fences.

Rebel:

Did you use an oil based or water based stain on the wood?

How long after staining did you apply the polyurethane?

To your knowledge, was the polyurethane ever "dry to the touch" after it was applied.

If you used oil based stain and oil based poly, you at least have the comfort of knowing that once the mineral spirits finish evaporating, it'll be good. Oil based products cure by reacting with the oxygen in the air. Cold temperatures slow that process, but don't interfere with the mechanism by which that curing happens. So, you can paint a fence in the middle of a Manitoba blizzard with oil based paint (or oil based polyurethane). The fence will be tacky all winter, but when the warm weather comes in spring, it'll dry normally just as though you you'd painted it in mid-summer.

On 3/1/14 5:41 PM, Ed Pawlowski wrote:
On 3/1/2014 4:35 PM, Rebel1 wrote:
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.

Some cut.

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.

Would a good old fashioned fan help any?

On 3/1/2014 10:01 PM, Dean Hoffman wrote:


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.

Would a good old fashioned fan help any?

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

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.


"Rebel1" wrote in message
...
| 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

On 3/2/2014 9:15 AM, Mayayana wrote:
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.


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.

Ed Pawlowski writes:

On 3/2/2014 9:15 AM, Mayayana wrote:
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.

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.

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

--
Dan Espen

On 3/1/2014 10:01 PM, Dean Hoffman wrote:
The wax may prolong the process. I'd try to keep it as warm and dry as
possible. The sun will help.

Would a good old fashioned fan help any?


Simple, effective. Works for me.

--
..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On Sat, 01 Mar 2014 17:27:02 -0500, Rebel1
wrote:

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

I'd be curious of how thick the polyurethane coats were applied.

The last desk top I finished were in very thin coats, allowed to set,
lightly sanded and others coats applied.

Worked for me. A heavy coat would have been a bad idea, I think.

It kept from having bubbles in the finish.

Rebel1 posted for all of us...

And I know how to SNIP


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

Do you have gas heat. Sometimes the mercaptan reacts with poly or waxes.

--
Tekkie

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