What substance should you NEVER pour on a grease fire?

In the case of a grease fire, pouring water on it can lead to disastrous consequences. When water is added to a grease fire, it can cause the burning oil to splatter and spread the flames, significantly worsening the situation and posing an increased risk of injury or property damage. This is because water and oil do not mix; the water will sink and immediately vaporize, exploding into steam and propelling burning grease.

On the other hand, substances like salt and baking soda can be effective for extinguishing small grease fires because they can smother the flames by cutting off the fire's oxygen supply. Flour, however, is not a safe choice, as it can ignite and exacerbate the fire. Hence, avoiding water is crucial in these situations to ensure safety.