You can use a hair dryer to dry watercolor paper after you've stretched it, and to dry sections of the painting as you're painting. But you don't want to turn the hair dryer up high, no matter how impatient you are, because you don't want the water turning into steam or overheat (scorch) the paper. Don't put the hair dryer close to the paper either. Keep at least 10 inches (25 cm) away from the surface.
Put the hair dryer on its lowest setting, and wave it back and forth across the paper to ensure it dries evenly. You don't want one part to dry out before another, as the sheet may then buckle. If you're working on unstretched paper, use the hair dryer on the back of the sheet as well as the front.
How will you know when the watercolor is dry? If it's just a sheet of stretched watercolor paper, you can obviously touch it with your fingers to find out. But if you've painted on it, touching it will muck up the painting if it's still wet. It takes a bit of practise, but you can tell by hovering your hand just above the painting; if it's still damp, it'll feel cool. (Try it with a dry and a wet sheet of paper to teach yourself what it feels like.)
If you find yourself getting too impatient for a watercolor painting to dry, try working on three or four at a time, swapping between them.
