what is adequate ventilation?
Have you ever noticed how often the instructions on paint cans and other products warn about the need for “adequate ventilation”-without ever explaining exactly what that is?
Opening windows obviously helps. So does turning on a fan. But is it better to aim the fan as an exhaust, so that it pushes dirty air out? Or as a supply, so that it blows fresh air in?
Some years ago, the painters' union put monitoring devices on a painter and tested several scenarios. It was 30 times more effective to open a window, place a fan in a doorway at the far side of the room and use the fan to blow fresh air toward the painter than it was to place the fan in the window and aim the blades out. (To experience this phenomenon yourself, put your hand close to your face and blow. Then keep your hand up and feel the difference as you suck air in.) Start painting at the far side of the room, near the open window, and work toward the fan so you always breathe fresh air.
Beware of turning the fan speed too high, however: too much air movement can cause problems with some water-based paints. They are designed so that as the water evaporates, the resins (the “glue” of the paint) come together to form a uniform film. If the water leaves too fast or too slowly, the resins don’t coalesce properly.