Learners add two dyes to mineral oil and water, and then compare their miscibility (how well they mix) in each. Learners discover that the molecular structure of a dye determines whether it will mix well with oil-like substances or with water-like substances. The red dye in the experiment is an industrial dye used to color wax ceramic molds. Because mineral oil has a very similar molecular structure to wax, the red dye mixes well with mineral oil. The blue dye is an industrial food coloring that mixes well with water. Most food contains water, so the blue dye works well for food coloring.