organisms that have a Gram-positive cell wall will resist decolorization with methanol and will retain the purple color of the crystal violet.

Gram-negative organisms will not be stained by the crystal violet, as they do not have peptidoglycan in their cell walls.

Gram-positive organisms will show a brown stain caused by the exposure to iodine, which stains both lipid bilayers of these organisms.

organisms that have a Gram-negative cell wall will be devoid of safranin staining, as their cell wall prevents safranin access to the lipid bilayer.