What is the purpose of a tortillon in drawing?

A tortillon is a tool primarily used in drawing to blend and smooth out pencil, charcoal, or pastels on the paper. Its design, typically made of tightly rolled paper, allows artists to achieve subtle gradations of tone and create a softer appearance between lines and areas of shading. This blending technique is particularly important in achieving realistic textures and depth in a drawing, making it a critical tool for artists looking to enhance their work's dimensionality.

The other options refer to functions that are not the primary use of a tortillon. While applying paint and creating sharp lines are important in various artistic techniques, these are not actions associated with a tortillon's design or intent. Similarly, an eraser is typically used to correct mistakes rather than a tortillon, which focuses on blending rather than fixing errors. Thus, the purpose of a tortillon in drawing is clearly aligned with the ability to blend, enhancing the quality and finish of the artwork.