Hoechst stains are part of a family of blue fluorescent dyes used to stain DNA. Ascospores are stained with Kinyoun stain and ascospore stain. When virions are coated with stain (positive staining), fine detail is obscured. Different proteins may also stain differently, which interferes with quantification by staining. Many berries contain juices that can easily stain, affording use as a natural dye. However, some varnish products are marketed as a combined stain and varnish. Occasionally, during peeling of ripe fruits, the purple exocarp juice may stain skin or fabric. Building stone containing pyrite tends to stain brown as pyrite oxidizes. Contact with skin will result in a long lasting pinkish/purple stain. However, dried henna leaves will stain the skin if they are mashed into a paste. Whole, unbroken henna leaves will not stain the skin. Hoechst dyes are often used as substitutes for another nucleic acid stain called DAPI. This is why red beetroots leave a purple stain. Cetylpyridinium chloride and chlorhexidine can temporarily stain teeth. These visibly stain the ticking and seep through into lower layers.