Gram staining reaction is a differential stain used to differentiate between gram-positive and gram-negative bacteria. These bacteria turn purple and red respectively after the experiment.

Procedure:
1. Add crystal violet dye to bacteria. Both gram-positive and gram-negative bacteria turn purple after this step.

2. Then add Gram’s iodine solution. The stain retains better by forming an insoluble crystal violet-iodine complex. Both gram-positive and gram-negative bacteria still remain purple after this step.

3. Next is the differential step which we add Alcohol decolourizer, a mixture of ethyl alcohol and acetone. Gram-positive bacteria retain the crystal violet-iodine complex while gram-negative gets decolorized.

4. Finally, add counterstain safranin. As the gram-positive bacteria are already stained purple, they would not be affected by the counterstain. Gram-negative bacteria, which are turned colourless, turn pink.

Gram staining reaction is a differential stain used to differentiate between gram-positive and gram-negative bacteria. These bacteria turn purple and red respectively after the experiment.

Procedure:
1. Add crystal violet dye to bacteria. Both gram-positive and gram-negative bacteria turn purple after this step.

2. Then add Gram’s iodine solution. The stain retains better by forming an insoluble crystal violet-iodine complex. Both gram-positive and gram-negative bacteria still remain purple after this step.

3. Next is the differential step which we add Alcohol decolourizer, a mixture of ethyl alcohol and acetone. Gram-positive bacteria retain the crystal violet-iodine complex while gram-negative gets decolorized.

4. Finally, add counterstain safranin. As the gram-positive bacteria are already stained purple, they would not be affected by the counterstain. Gram-negative bacteria, which are turned colourless, turn pink.