Oil-based polyurethane reportedly has some toxicity during application, but it is easier to apply and provides a superior finish compared to water-based polyurethane.

This means that while I may get away with not using a mask while applying a water-based polyurethane, I should never think of applying oil-based polyurethane unless I'm properly (NIOHS) masked. Whether I'm applying one or the other, there should be ample air circulation.

My question is: Does oil-based polyurethane have any toxicity once it has set? If a bedroom remains vacant for one week with the windows open for the week, is there any subsequent risk from inhaling the vapors, especially during long winters when the heating system will just circulate the same air?

  • You need to be much more specific about which products you are talking about.I paint 2-part urethanes and they are very different creatures than 1-part in either "oil" or water based. Apr 13, 2016 at 21:36
  • Anything is toxic if you eat enough of it. Don't eat polyurathane, fresh or cured.
    – Grant
    Apr 13, 2016 at 21:44

1 Answer 1


There are many discussions on this to be found. The bottom line is that any product has a parabolic curve of off-gassing over time. It reaches extremely small quantities after a few days of suitable curing conditions, and is almost at zero after a few weeks. Very few people would detect substantial odor after that.

I finished my office desktop with oil-based poly last fall. It was cured for long-term contact after about 2 days, but I could smell it for a few weeks. I don't notice it anymore a few months later. Your mileage may vary and depends largely on your personal definition of "toxicity".

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