Mona Lisa Smile

• One of the most studied aspects of the "Mona Lisa" is the smile of the subject. Many viewers claim that the woman is first smiling and then the smile becomes a blank expression. While the Harvard neuroscientist Dr. Margaret Livingstone claims that the changing expression is due to differing levels of contrast and light as they are perceived by the brain, Da Vinci used a technique called "sfumato" to create this effect.
  
  Sfumato is an Italian technique that uses dark and blurry colors to create an ambiguous effect on the canvas. Da Vinci did not limit this technique to the smile of the figure. In fact, almost every portion of the painting was painted with sfumato. The question of whether or not the woman has eyebrows is also often indistinguishable due to the sfumato effect.
  
  

Oil Layering

• Da Vinci created the "Mona Lisa" with oil paint on a wooden palette. His technique was to first apply a base using gray or brown and then finish with finely placed dark colors. Although most artists used a base paint, Leonardo made the base very detailed to add to his sfumato technique. Brush strokes were light as several layers of millimeter thick paint were applied to the entire surface.
  
  In order to paint over the base, Leonardo applied the additional colors in a glaze. This allowed the original layer to show through each layer and add form to the subject and background. The base is especially visible in the uppermost portion of the painting where it blends into the green-toned sky background. By continuing to use dull and blended colors, the original "blended" effect was conserved.
  
  

Aging

• With all sfumato paintings, age often plays a vital role in the effect. This is especially true with the "Mona Lisa". As the painting has been preserved for more than 500 years, unpreventable aging and climate effects have only added to the blurry and blended colors. If Leonardo had used bright colors, the effects of aging would likely be much more evident.