Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

August, 2004

Odors from House Painting

Q. After painting a bedroom I had noticed a paint odor remaining in the room for weeks after the paint job. The odor remained in the room despite plenty of ventilation. In order to try to get rid of the odor, the room was primed (with 2 coats of oil-based primer) and then re-painted (with latex paint). However, the odor still persists. Despite the paint being completely dry, I can actually smell the odor, though subtlely, on the painted wall itself. Any idea why this odor remains and how I can alleviate this problem? Many thanks for any suggestions you may have.

Thank you for your email. When something has a smell, (or odor) we are inhaling very small concentrations of a chemical compound that is in present in the air we breathe. Human beings can detect concentrations in parts per billion (ppb), while some animals are even more sensitive and can detect concentrations that are imperceptible to the human nose.

If we are bothered by the smell of a liquid, it is because a very small concentration of the liquid is evaporating and we can detect the molecules of the vapor that we inhale.

Oil-based paints predominantly have an odor due to the organic solvents that are incorporated in their formulation. As the solvents evaporate through the paint film we can easily smell them. Fortunately, most of the solvents evaporate fairly soon after painting has been completed, but bear in mind that some solvents evaporate very quickly while others take longer to escape from the paint film.

Oil-based paints also contain liquid plasticizers and resins that evaporate extremely slowly. Unfortunately, they often have unpleasant odors.

Soon after oil-based paint is applied we predominantly smell the solvents, but as time has passes we start to smell the slower evaporating plasticizers and resins. Over a period of time the evaporation of minute concentrations of these ingredients will be so small as to be undetectable.

The best method for eliminating odors is to expose all the painted surfaces while ventilating the area with as much air as possible.

If you have painted inside of closets, cabinets, drawers, etc. open them to allow the volatile compounds to escape. Eventually the evaporation of the ingredients will be below the detectable limit and you will no longer experience the odor.

One method for masking odors is to place small bags of coffee, vanilla essence or other fragrances in the areas where the odors are most offensive. Be aware, however, that this ploy only masks the odors but does not remove them.

Best wishes,

Ron Joseph

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