Allow the slide to cool before applying the stain. Several smears can be applied to a single slide. The Gram stain is the most useful single staining procedure in bacteriology. Cells that retain the crystal violet dye after decolorization are called Gram-positive. Bacteria that are decolorized by alcohol take up the pinkish safranin counterstain and are called Gram-negative.
Air dry a thinly spread smear and fix it with heat by passing slide through the flame of the burner.
The slide should not be too hot after the smear is fixed by heat. Flood the smear with crystal violet solution and let stand for one minute. Flush off the stain with water and then cover the smear with the Gram's iodine mordant. Let stand at least one minute. Rinse with water and drain off the remaining water.