Lugol's Iodine Solution

Lugol's iodine, also known as aqueous iodine and strong iodine solution, is a solution of potassium iodide with iodine in water. Lugol's iodine was first made in 1829 by the French physician Jean Lugol. It can be used as a cell stain, making the cell nuclei more visible. As a mordant when performing a Gram stain. It is applied for 1 minute after staining with crystal violet, but before ethanol to ensure that gram positive organisms' peptidoglycan remains stained, easily identifying it as a gram positive in microscopy.