Is smelly polyurethane sealant toxic?

Q: My husband applied a polyurethane sealant around the windows. We have a 16 month old son. I never noticed the smell in his room, but the next morning I noticed it. We had already slept in the house. I stayed the next four nights out of the house with him. However, I continue to smell the polyurethane around the windows and in one room.

The warning label specifically states four outdoor use only and it was only used outdoors but I’m afraid of the slight fumes that seeped through the windows. Have I endangered my child?

A: Unless he was having trouble breathing, coughing, red/burning eyes I would think the exposure to him, if any, has had no bad effect. Most labels that I’ve read involve dangers of long term, over-exposure to the solvents, such as one may suffer who works with it every day.

Related Q: We had our floors refinished with a stain and oil polyurethane 6 days ago; we’ve been airing out the house for 4 days. I have two little guys (2.5 year old and a one week old newborn) and I’m very concerned about toxic issues, especially for the newborn, but we also need to move into the house. Is it most critical that they’ve dried or that they’ve cured (have read on your site citing can take around a month). Also, we have a basement that did not have any flooring work done; would it be beneficial to live in the basement while the floors cure? Thanks for advice for this protective mama.

A: There is a difference between the coating drying and then curing. The finish is dry when all the solvent has evaporated from the film. Trying to apply another coat of finish before this occured would likely cause the previous coat to wrinkle. This generally happens in 8-12 hours. Sometimes sooner. Sometimes longer, depending on environmental conditions. After this it is a good idea to open the windows to ventilate the rooms or house and let in some fresh air, while helping to flush any vapor that may still linger. I can often tell when I walk in the door the next morning if the finish is dry and ready by the smell. Still evaporating solvent will cause eye and throat burning. You don’t want to stay inside if this is happening. Curing is what happens to the coating over the coarse of several days to several weeks, depending on the finish used. This has nothing to do with off gassing of solvents. It is a reference to the finish, the urethane resins reaching their maximum hardness by exposure to air. If there is no eye burning when inside the house, I would personally feel safe staying inside. It isn’t necessarily safer staying in a basement as solvent vapors, heavier than air will tend to fall rather than rise.

Part of our problem at this point in time, IMO, is that we have been exposed to so many toxins from multiple sources, some people are in overload. So, the slightest hint of a smell of solvent or even something like walking past a flower shop with dried flowers can set them off. Under normal circumstances, a slight exposure to a tiny solvent amount would cause no issues. Having said all that, there shouldn’t be any solvents to worry about. They aren’t still coming out of the coating.

Related Q: I am 32 weeks pregnant. We just had our hard wood floor redone with 3 layers of oil-based polyurethane coatings. I can smell the odor. Does this mean the floor is still releasing toxic chemicals? Is this harmful to my baby?

A: The solvent itself has evaporated from the coating within 24 hours generally. If the solvent has not left the coating, applying another layer on top would likely cause wrinkling of the finish. So, no the finish itself is not off gassing. There may be some smell remaining because the solvent has entered the house or room and has not been thoroughly ventilated. Open doors and windows and allow some fresh air in. The only reason I would be concerned is if your eyes start burning. That would mean there is a high concentration of the active solvent in the air.