What is the period of time called that a chemical is left on a surface before it is rinsed?

• A. Contact time
• B. Dilution time
• C. Setting time
• D. Drying time

Answer: (A)

The period is called contact time. It’s the dwell time a disinfectant or chemical must stay on a surface to have its intended effect before you rinse or wipe it off. Following the label’s prescribed contact time is crucial because the chemical needs that amount of time to interact with microbes and achieve the needed kill or deactivation. If you rinse too soon, the product may not have fully worked, and microorganisms could survive.

This dwell time can vary with the product, the level of organic material on the surface, temperature, and the type of surface, so always follow the label instructions for the exact duration. After the contact time has elapsed, you proceed with rinsing or wiping as directed. Drying time is a separate consideration—the time it takes for the surface to dry, not how long the chemical must stay to be effective.