Retarders are substances used to slow down or delay chemical reactions, particularly in processes like cement setting or paint drying. They help control the timing of these reactions, allowing for better workability and application. Commonly used in construction and manufacturing, retarders ensure that materials remain workable for longer periods. In the context of concrete, retarders can prevent the mixture from hardening too quickly, which is especially useful in hot weather. Similarly, in paints, retarders can extend the drying time, allowing for smoother application and blending of colors.