Watercolor painting is an amateur's medium, beloved of the ''Sunday painter.'' And yet it is also among the hardest of artistic techniques to master, for unlike oil or even acrylic painting, where the paint stays where you put it, water-soluble paint is runny and difficult to control. Mistakes cannot easily be painted over, either, for the paper is absorbent and adding more paint often results in a watery mess. Painting with water-soluble paints is an ancient art, dating all the way back to the decoration of caves during Paleolithic times. It is also common to many world cultures, including China and India. But its modern Western history begins in the Renaissance, when it was used to beautify manuscripts as well as for botanical and wildlife illustration. During the 18th century, particularly in England, it was embraced by amateur artists and more established painters for wider cultural, scientific and even travel uses. [ABSTRACT FROM PUBLISHER]