Oil-based paints and primers cure by air oxidation. Oxygen from the air reacts with oils and the liquid resins are converted to solid films.
A possibility may be that the primer's surface may have felt 'dry', but underneath the curing process was not complete, especially if a thick primer coat was used.
- Applying wall paper over this surface may have encapsulated the curing paint. Different wall coverings can transmit different amounts of vapor depending on how they are made.
- For example, vinyl wall coverings have low permeability, they 'breathe' very slowly and this will substantially slow down the oxidation process.
Unfortunately, time is needed for the smell (aka VOCs) to go away. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects.For more information on Volatile Organic Compounds (VOCs), please consult the EPA's website (here) regarding steps to reduce exposure.
How long until the smell is gone? Paint thickness, covering permeability and fresh air movement all contribute to the curing process. Moving fresh air through the room is essential and some options are (ranging from least to most expensive):
- opening windows for cross ventilation;
- turning on a bathroom fan and opening a window in that room to exhaust air; or
- a more aggressive and expensive approach would be renting an air scrubber with Particulate/Carbon Adsorption/HEPA filter.
For more information:
Read "My wife is chemically sensitive. What's the best way to get rid of stubborn paint odors in our home?" a Q&A answered by Steve Rush.