Cotton Blue Stain is formulated with lactophenol, which serves as the mounting fluid and the dye, cotton blue. Lactic acid preserves the fungal structure and clears the tissue while phenol acts as a disinfectant. The high concentration of phenol deactivates lytic cellular enzymes, thus the cells do not lyse. Cotton blue is an acid dye that stains the chitin present in the cell walls of fungi. The stain imparts blue color on fungal hyphae.