Fire-retardant foam

Fire-retardant foam is a foam used to retard fires. It is also among the mightiest weapons known to Transformerkind. Even across the generations, the legendary power of fire-retardant foam may be slightly diminished, but it is still to be feared and respected.

It is sometimes dispensed from fire extinguishers.

Fiction

The Transformers cartoon

When the Autobots were disabled by a Decepticon sneak attack, Spike prompted the Autobot computer Teletraan I to release fire-retardant foam. The foam landed on the Decepticons and immediately shorted out their circuitry. Recognizing this unbeatable foe, Megatron ordered an immediate retreat. The Ultimate Doom, Part 1

The Autobot Ironhide was also capable of releasing the substance, among other compounds, from a nozzle embedded in his wrist. That guy could shoot just about anything. Why he never used its almighty power to annihilate the Decepticons once and for all is not known.

Cybertron cartoon

Coby used fire-retardant foam to escape the clutches of Sideways when he had them cornered in a passageway within the Atlantis. It covered his face as he screamed madly, allowing him and his companions to flee. Escape

Animated cartoon

Optimus Prime made use of it as one of his weapons, and it proved capable of debilitating even a mighty Decepticon or two. It knocked out Starscream's jets in mid-flight Transform and Roll Out and rendered Blackarachnia incapable of moving for several seconds while she cleared it out of her eyes. Along Came a Spider