Tressa Wave Test Instructions

Float a clean, dry hair in a bowl of water. After a moment, does it stay floating atop the water or does it sink under? Floating hair indicates healthy porosity, which means the hair is healthy enough to receive a chemical service.

Hair under the water is too porous and should not be waved. Remove the hair from the water and towel dry it. Now you are ready to perform the IT test.

Take the strand of hair between the thumb and forefinger of each hand, about 1 ½-2 inches apart. Slowly bring your thumbs toward each other. The hair will form an arc. As you continue to move your hands together, the hair will suddenly twist and form a loop.