Warm is good, hot is bad
This watercolor technique can save you SO much time. I've used many blow dryers over the years to speed the drying of washes between painting stages. It is a fast and efficient and there are no ill consequences if used properly. I ALWAYS use the "low"setting, no matter how impatient I am. I currently use a 1600 watt blow dryer with a "cool" button that turns off the heating element to use the fan only.
No steam allowed!
Hold the blow dryer about 10" - 12" from your painting and move across the surface in overlapping strokes of warm air. Pretend you are spray painting the surface. DO NOT hold the blowdryer on a stubborn damp area for a prolonged period. You don't want steam, and you don't want the actual drying speed to affect how an area of the painting looks. (It can)
Paper is porus!
As you deposit paint on the surface, the moisture also soaks through your paper. If you want your paper to lay flat don't forget to dry the back also. I point the dryer under the edge of the painting, forcing the warm air under the paper and drying the underside. I rotate the board and do this under each edge for a few seconds each.
How damp is it?
Patience is a virtue. (yeah, yeah) You can avoid the hassle of a blow dryer if you keep several paintings in process at a time. Work on one for a bit, set it aside and work on another project. It's like being an artist. When I'm working on a watercolor painting I usually use a traditional approach using multi-technique underpainting and glazing. I need time between each phase of painting to gauge my next steps. A 10-15 minute break can dry the painting enough to start back to work. I test the dryness of an area with the back of my hand. Don't touch! With practice you can feel the cool evaporation of an area that isn't dry yet by hovering your hand close to the surface. Really.
