Fires are caused when materials have reached their igniting stage and when classified as combustible. A fire spreads out when surrounding materials are exposed to heat, fueled by substances of its components and oxygen in the air that sustains any combustion.

To stop a combustion from happening we can either resort to chemical or physical action, which would be dependent on the material on fire and the classification of the fire.
Water Additive Fire Extinguishers are part of the physical actions used to stop flames from spreading. There are three ways of Water Additive Fire Extinguisher retardants which are used for particular types of fire :

Wet Chemical is when water is combined with a chemical, commonly used for extinguishing purposes, water is added to potassium acetate. When both water and potassium acetate compounds are combined a salt is formed. The reaction of both water and potassium acetate forms a crust over a fire which contains it from spreading. This particular Wet chemical additive is recommended for types ‘A’ and ‘K’ fires which involveĀ  combustible materials (paper, chips of wood, plastics) or burning oil (cooking or motor).

Wetting Agents on the other hand are detergent based, when added to water creates a break in the surface of a blaze. When a break occurs, it is easier to drench a fire to smoldering level while further spray will stop the fire from re-igniting.

Polymer in water/oil emulsion puts out fire types ‘A’ and ‘K’. An emulsion is the mixing of oil and water, when combined with a polymer it becomes a gel-like substance that also absorbs heat. This Water Additive Fire Extinguisher works by breaking the fire’s surface then easily spread a gel-like protection and cooling layer on the burning material/s. Whether sprayed at the base or from the top, this polymer/emulsion contains, cools surfaces or burning materials and stops fire from reigniting.

Several of Water Additive Fire Extinguishers are being researched and developed since water is abundant and doesn’t contribute to deadly emissions.