This video demonstrates how to caulk a sink. For this project, you will need a tube of caulk, a towel, and an X-acto knife. Cut off the tip of the tube with the knife. Cut it at an angle, which will make it easier to make a smooth and even line. Make sure the area is clean and dry. Slowly make a ridge around the sink. Dap brand caulk comes with a cap, which will help to keep it fresh for the next time that you use it. When you are done, seal your tube and put it away. Use your fingers, a towel, and water to smooth out the line and clean up excess.