Pastels have been in use since the Renaissance, although the peak of their popularity did not come about until the 18th century, when Joseph Vivien became the first artist to be called a “painter in pastel”. However, Vivien mainly utilized pastels for preparatory work, and finished his paintings with other mediums. The first paintings made entirely from pastels were created by Italian artist Benedetto Luti. Perhaps the most famous pastel artist was Edgar Degas, who was revered for his pastel paintings of ballerinas, such as Dancers Practicing at the Bar and Dancers, Pink and Green. His student, Mary Cassatt, was credited with bringing the popularity of pastel to the United States. Pastels are pure powdered pigment held together by a binder in stick form. It looks a bit like a piece of chalk and a bit like a crayon, and they are held the same way that you would hold a pencil or a paintbrush with your fingers. There are four types of pastels: soft pastels, hard pastels, pastel pencils, and oil pastels (or Cray-Pas). Soft pastels, hard pastels, and pastel pencils all utilize a gum or resin binder, and they are all compatible, and suitable for use within the same painting or drawing. Oil pastels utilize an oil and wax binder, which gives them a texture similar to oil paints, and they cannot be blended with other types of pastels.