Clay masks work to detoxify the skin, because they have a natural ability to tighten and pull. They extract impurities from both the surface, and just underneath the skin. These impurities include excess oils, dead skin cells, and all the grossness that clogs your pores.
Oh pustules, how I loathe thee! They are categorized as inflammatory pimples. A pustule occurs when the bacteria from the dead skin cells and oils in your pores attract other strains of bacteria.