GE Silicone I All Purpose 100% silicone caulk can withstand all weather conditions, and will remain permanently waterproof, flexible, and shrink-/crack-proof. Outdoor elements such as heat, sun (UV rays), and extreme cold can cause acrylic caulking to crack and crumble over time, leaving gaps for air and water to seep through. Those leaks can lead to water damage, mold growth, and higher energy bills. 100% Silicone sealant is widely considered to be the best caulk for sealing areas that will be exposed to water.