Sfumato is a term used to describe the blending of tones or colors so subtly that they melt into one another without perceptible transitions. It is a painting technique for softening the transition from one color to the next. It is the gradual fading away from one color and seamless fading into the next. The sfumato technique allows colors and tones to shade gradually into one another, producing softened outlines or hazy forms.
Sfumato was defined and refined by Leonardo da Vinci and his apprentices. They made very subtle gradations, void of lines or borders, fading like vapor from light to dark and dark to light areas. In essence, sfumato was deftly employed for a highly illusionistic rendering of facial features and for atmospheric effects in the background of the figures and in paintings rich with natural features.