Which of the following is NOT a characteristic of effective extinguishing agents?

Effective extinguishing agents are designed to suppress or extinguish fires efficiently while ensuring safety for users and the environment. High effectiveness is crucial because an extinguishing agent must effectively put out flames and prevent re-ignition, making it a vital characteristic. Minimal toxicity is also important, as many applications require agents that will not pose significant health risks to firefighters or occupants in case of exposure. Low cost is often a consideration, particularly for widespread use, but it does not impact the effectiveness of the agent itself directly.

In contrast, high viscosity does not contribute positively to the characteristics of an effective extinguishing agent. Agents generally need to be fluid enough to be deployed easily and reach the fire effectively. High viscosity could hinder the dispersal of the agent, making it less effective at combating the fire. Thus, identifying high viscosity as not a desirable characteristic highlights the need for effective functioning and safety in fire suppression scenarios.