Over time the mill applied carpet protectors can loose their effectiveness. This is due to the fibers being abraded during heavy traffic. Since the biggest enemy of the protectors is abrasion from traffic, and traffic varies with each situation, the general recommendation for re-application is after each professional cleaning. Carpet protectors is an insurance for you, your carpet will give you the same results every single time its clean. This product is recommended for people with an active house because things happened, and you can only hope to be able to cleaned them up. AquaTec uses Dupont Teflon's technology to provide more repellency than any other carpet protector. Teflon advanced delivers its protection by forming a molecular shield around each carpet fiber. It repels liquids, allowing spills to be removed before staining or wicking can occur. This product keeps dirt from sticking to the fibers, making carpets easier to care for. Unlike other protectors, Dupont Teflon Advanced is applied with a spray gun, dries quickly with your carpet, and leaves no odor. It is non-toxic and safe to use around family, and pets. (solvent-free)