subject: Adding Volume to Hair with a Flat Iron [print this page] Because you are lifting the flat iron upwards this is going to give you lift at the roots, in return adding volume to your hair. If your hair is known to fall flat later in the day you can help avoid this by using a volumizing hair care product before styling the hair with your hair iron. A light spray of flexible hold hairspray once you are finished styling hair also works to help hold your style.